# Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation



## earthad1 (Apr 1, 2008)

Hi everyone,

I recently had moisture issues in my attic that seemed to be caused by warm air escaping from my home into the attic and not being vented out properly. 

I have recently gotten my attic toped up with blown-in insulation (6 inches) which now gives me an R-value of about 50.

Problem now is that there is some frost build-up on the attic roof and the nails look like little snowballs.

It seems that the problem with my attic now is not enough intake ventilation from the soffit vents since the frost in the attic is most prominent at the ends of the roof. It looks like the plywood simply goes to the end of the soffit, therefore, there are no holes to vent from. I have gable ends, but these do not seem to be enough to vent any warm air that may be escaping from my home into the attic.


I may need to get a ridge vent installed on the peak of my roof for now because I can't do much about the soffit vents at the moment... in the spring I'm going to drill small holes in the plywood beneath the soffit vents (not too many to weaken the wood but enough to get some good aitflow going).


So it seems like I fixed one problem, but created another, or, the issue with the moisture was ventilation all along and not lack of insulation (though the extra insulation can't hurt I suppose).

The insulation is a big improvement, but probably what happened was that the initial moisture I had in there was being caused by warm air coming into the attic from the kitchen and bathroom upstairs, and because the soffit vents were not ventilating properly, this caused a temperature differential in the attic, which caused the condensation... so adding the insulation is keeping the warm air out more, but at the same time, the warm air that IS getting in is being trapped more, so when it hits the underside of the roof, which is much colder, it turns to frost..

frost is better than water, but still needs to be fixed.

Also, I have an air exchanger up there that currently does not work. I have bought a new one but it is too large to fit in the attic hatch :furious:

So ayways, I'm thinking the air exchanger vents may be contributing to the problem (small air leaks from these vents. I have some loose material that I could just stuff into the vents (similar to synthetic pillow stuffing), but not in the actual ducts. Also, should I seal off the intake/exhaust vents outside going to the air exchanger?

I'm looking for some opinions on this issue and what would be the best course of action to take at this point. I'm thinking the ridge vent is a good idea, but I have no idea how much something like this usually costs $$$.

Thanks in advance...

Eric.


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## AllanJ (Nov 24, 2007)

Want to put an intake fan in a gable vent for the time being? Of course you will need adequate square inches of vent at the other end of the house to let warmer air out.

Also seal up any holes letting warm inside air up into the attic, including gaps in heating and air conditioning ducts as quickly as you can.

Nothing should exhaust directly into the attic. Outside exhaust ducts should not be near soffit vents or other attic vents where the exhaust air could find its way in.

If frost accumulates to look like balls, it will melt and drip all over the place even on a winter day when the sun is out and there is no snow on the roof.


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## mpepin (Nov 19, 2008)

It seems like you have a decent understanding of the forces at work. The new insulation is helping keep the house warmer and the attic colder, but there's still moisture getting up there and not enough ventilation. It sounds like you have soffit vents and gable end vents. This condition typically doesn't work, especially on larger homes. You need soffit vents AND a ridge vent. When wind blows across your roof, a slight pressure differential causes air to be pulled out from the ridge vent which is replaced by air coming in from the soffit vents. Without both, the system doesn't work. Adding a ridge vent shouldn't cost much, I recently replaced a 40' long one for $500.


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## earthad1 (Apr 1, 2008)

mpepin said:


> It seems like you have a decent understanding of the forces at work. The new insulation is helping keep the house warmer and the attic colder, but there's still moisture getting up there and not enough ventilation. It sounds like you have soffit vents and gable end vents. This condition typically doesn't work, especially on larger homes. You need soffit vents AND a ridge vent. When wind blows across your roof, a slight pressure differential causes air to be pulled out from the ridge vent which is replaced by air coming in from the soffit vents. Without both, the system doesn't work. Adding a ridge vent shouldn't cost much, I recently replaced a 40' long one for $500.


Yes, I do have soffit vents and gable ends. I don't think the soffit vents are doing much since when the contractor came over to add the insulation he noticed that they may be covered by the plywood from the roof and therefore not effeciently taking care of the ventilation. He suggested I remove the soffit vents, drill small holes into the plywood, then put the soffit vents back on. 
My home is not very large. It is a 1300Sqft 4-level split. Problem is I have 2 roofs so I would need a ridge vent on both. 

Do you think, the drill holes, on top of adding the ridge vent, is a good idea?

Thanks for the reply.


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## earthad1 (Apr 1, 2008)

AllanJ said:


> Want to put an intake fan in a gable vent for the time being? Of course you will need adequate square inches of vent at the other end of the house to let warmer air out.
> 
> Also seal up any holes letting warm inside air up into the attic, including gaps in heating and air conditioning ducts as quickly as you can.
> 
> ...


Where can I get an intake fan? Like a local hardware store? 
What can I use to seal these holes? I'm thinking, as I stated earlier, that a large amount of the moisture is most likely coming from a few places.

1. My 2 attic hatches are nothing more than slabs of fiberboard sitting on the hatch frame.

2.The bathroom fan (My wife, who just got home from the hospital with my new son was taking a bath when she heard dripping) I came directly home from work to realize that the dripping was caused by frost that had built-up on the metal casing of the fan and the steam from her bath caused it to melt. This is what lead me to investigate the attic when that's when I noticed the frost. The exhaust for this fan was initally blowing into my attic so we attached the hose to the gable end so that it vents directly outside now. My second bathroom on the third level's fan vents directly outside and does not go into the attic.

3. These Air Exchanger vents, which are not currently being used may be allowing warm air so seap through the openings in the ceiling. As I said, I do have some pillow stuffing type material that may help short-term...

What do you think about the idea of blocking the exchanger vents with this material?

Thanks for the reply.


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## Termite (Apr 13, 2008)

I personally would not consider the powered vent an option at this point. Before you do that, you need to properly ventilate the roof. Drilling little holes near the soffit vents isn't adequate either, you need the full benefit of each vent you have. Even a powered fan needs excellent soffit ventilation in order to be effective.

As mentioned, cross-ventilation is critical. Soffit vents alone or ridge/rooftop/acorn vents alone are generally worthless...Both must be there and unobstructed to work effectively in conjunction with each other. 

There are lots of ways to vent a roof. Here, you rarely see ridge vents. Instead, a number of square roof vents or spinning acorns are installed.


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## AllanJ (Nov 24, 2007)

Hint: For an intake fan you might have an exhaust fan mounted backwards.

Unlike an exhaust fan, an intake fan does not have the tendency under some conditions to draw more warm humid air from the living space up into the attic.

The hose from the bathroom fan to the outside, should it run through the attic, should be insulated.

Anything, duct tape, etc. is better than nothing for sealing cracks where warm humid air from the living space or heating ducts gets into the attic.

For a whole house attic fan, at the very least cover the big louver in the ceiling with plastic sheeting taped all around but stuffing a blanket of insulation on top manually removed in the spring is even better. Same for the hatches.


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## earthad1 (Apr 1, 2008)

Ok, so I've installed some plastic over the attic hatches (The same you would use on windows in the winter) and I have stuffed the air exchanger vent with some pillow-type stuffing. So there potential air leaks are pretty sealed now. Hopefully this will at least slow the heat loss until I can get the attic ventilated properly.

The guy who topped off my attic should be here on Thursday to see what options we have, though I think a ridge vent/acorn is the way to go.

As I said, I have not been able to go outside and remove the soffit vent to see if in fact it is just one solid piece of plywood under those vents. 

If so, what would be the best way to go about it?




AllanJ said:


> For a whole house attic fan, at the very least cover the *big louver in the ceiling *with plastic sheeting taped all around but stuffing a blanket of insulation on top manually removed in the spring is even better. Same for the hatches.


I'm not sure what you mean by "Louver" Sorry. :-(


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## sunthas (Dec 29, 2008)

Every electrical box you have in the ceiling lets house air into the attic. These can be sealed around the box with caulking. By code nothing should be in the box but wires and the connection points. The backside of the box where the wires come out can be sealed with fire-proof foam, but none can be in the box.

Think about how the house is built, I'm sure its all covered with insulation now, but typically electrical wires are run through the attic and then back down in each wall to an electrical box. Holes are drilled through sill plates and studs to get the wires to that point, they are often not resealed. That means you have air going up through your outlets into your wall and up into your attic. Solution is to seal up the electrical box at your wall best you can. I recently had thermal imaging done at my house that showed these problems.

Also, anywhere air comes in helps make the problem worse. If there are air leaks around windows that lets the air in more easily, these should all be sealed as well. I had major air leakage around my washing-machine supply and drainage panel that was covered up with a trim piece, and more around my dryer vent. Turns out air was leaking out of my house from just about every conceivable source. 

Each doorway in the house leaks, the drywall isn't finished because it has trim covering it up. Sure enough the trim piece on the top of the door way isn't caulked (you can't see it anyway) and air leaks out (or in) there. That air must be going up into the attic. Some of the holes for the door knobs into the door frame were drilled too deep, sure enough air comes right through them. 

It was quite an eye opener for me. There are lots of places to seal up.


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## hoight boyd (Jan 4, 2009)

yup..I wnet into my attic before the top up blown in was done..sealed all electrical fixtures with vapour barrier, caulk and spray foam....wire holes in top plates..pulled back insulation from eves..installed a few styro joist thingies..then blew it in..
I had solid sofits as well but drilled a few holes before doing the vented soffit covering..I have 6 roof vents and two big gable vents..but just in case
I am checking tomorrow for frost build up on nail heads.


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## AllanJ (Nov 24, 2007)

Louver -- The semi-attractive grillwork that covers a fan opening or vent opening. For whole house attic fans it usually has movable parts to close off the opening but usually not good enough to prevent warm air from going up in winter.

Often the attic floor insulation, especially blown insulation, fills the eave soffit area and may even block existing soffit vents. Cutting new soffit vents therefore becomes a project. You need to clear away insulation and in most cases install (usually) styrofoam sheet baffles in the rafters to let air in and resist clogging as the insulation resettles.


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## Tom Struble (Dec 29, 2008)

you should also close up the gable vents after you 
put in the ridge vent and cut adequate soffit ventilation
so you dont short circuit what your trying to achieve


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## Wildie (Jul 23, 2008)

[email protected] said:


> you should also close up the gable vents after you
> put in the ridge vent and cut adequate soffit ventilation
> so you dont short circuit what your trying to achieve


 Yep! CMHC in Canada specifically forbids gable venting used in conjunction with soffit venting! In my home I placed a rubber seal all around the perimeter of the attic door jamb! I also glued a stack of stryrofoam on the top of the door also!


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## Andrew Whitehead (Dec 31, 2008)

if you are getting that much condensation in your attic, did you make sure that you had a proper vapour barrier down before you had the insulation blown in? If not, the insulation maybe slowing the heat loss, but he moisture is still going through the same as before, if not faster since the inside of your house is warmer.

The plastic you put on your attic entries is pretty much useless, you need 6mm for a proper vapour barrier. I would also put a strip of rubber down where board lies. Since that piece isn't insulated, you might also think about buying some regular insulation so you can have a piece sitting on top of the board to insulate it.

As others have said, make sure your bathroom vent, as well as the vent over your stove both blow right outside, and not just into the attic.

An option for the stove fan is to replace it, and put in a new one that has a carbon filter and have it blow into the house so you don't have to do even more roof work, and it is one less area for warm air inside the house to leak out.


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## earthad1 (Apr 1, 2008)

Wildie said:


> Yep! CMHC in Canada specifically forbids gable venting used in conjunction with soffit venting! In my home I placed a rubber seal all around the perimeter of the attic door jamb! I also glued a stack of stryrofoam on the top of the door also!


 
Hmmm, interesting... Could this be why my soffit vents may be sealed off? Because I have 2 gable vents???


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## earthad1 (Apr 1, 2008)

AllanJ said:


> Louver -- The semi-attractive grillwork that covers a fan opening or vent opening. For whole house attic fans it usually has movable parts to close off the opening but usually not good enough to prevent warm air from going up in winter.
> 
> Often the attic floor insulation, especially blown insulation, fills the eave soffit area and may even block existing soffit vents. Cutting new soffit vents therefore becomes a project. You need to clear away insulation and in most cases install (usually) styrofoam sheet baffles in the rafters to let air in and resist clogging as the insulation resettles.


 
These things?


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## earthad1 (Apr 1, 2008)

Andrew Whitehead said:


> if you are getting that much condensation in your attic, did you make sure that you had a proper vapour barrier down before you had the insulation blown in? If not, the insulation maybe slowing the heat loss, but he moisture is still going through the same as before, if not faster since the inside of your house is warmer.
> 
> The plastic you put on your attic entries is pretty much useless, you need 6mm for a proper vapour barrier. I would also put a strip of rubber down where board lies. Since that piece isn't insulated, you might also think about buying some regular insulation so you can have a piece sitting on top of the board to insulate it.
> 
> ...


Should there be a vapour barrier placed on the floorspace of the entire attic? I know there is some underneath those whole house fan vents because when I removed it to put some pillow stuffing stuff in there, I can feel the plastic, but I do not know if it covers the entire attic space...

Example:
layer 1 : Attic floor.
layer 2: vapour barrier 
layer 3: Pink insulation
layer 4: Blown insulation

If not, how on earth would I go about putting some now?


There is a piece of vapour barrier and some regular insulation sitting on top of the board. I have also stuffed a towel underneath where the board sits on the frame, then sealed it with stickey strips and plastic.

When he came to blow in the insulation, he attached the hose that goes from the bathroom fan directly to the gable end, though I do not think that hose is insulated. Would I need to buy another hose? or simply wrap a type of hose insulation around it?


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## Chemist1961 (Dec 13, 2008)

Drop by HD or Lowes . In the gutter/ soffit vent isle you will find the spec sheets on soffit to rooftop ratios for venting. Also try a few web sites for soffit ventilation info. I believe your square footage and pitch are part of the formula. No qusetion the soffits need to breath up through baffles now to vent the damp air trapped up there. As mentuioned check what`s venting into the attic from the bath fans, etc or you`ll be in nasty shape by spring. Don`t wait. If necessary reach out your bedroom windows to cut into the soffits, but investigate the baffles as well. One every other space is the norm in most new construction I have seen, at least one every 3rd.


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## earthad1 (Apr 1, 2008)

Chemist1961 said:


> Drop by HD or Lowes . In the gutter/ soffit vent isle you will find the spec sheets on soffit to rooftop ratios for venting. Also try a few web sites for soffit ventilation info. I believe your square footage and pitch are part of the formula. No qusetion the soffits need to breath up through baffles now to vent the damp air trapped up there. As mentuioned check what`s venting into the attic from the bath fans, etc or you`ll be in nasty shape by spring. Don`t wait. If necessary reach out your bedroom windows to cut into the soffits, but investigate the baffles as well. One every other space is the norm in most new construction I have seen, at least one every 3rd.


Thanks...

So, based on all the responses and the online reading I have done. This is what it seems I need to do.

1. Ensure any leaks or warm air that may be making its way up from the living space to the attic needs to be sealed off.

2. Ensure that air is able to enter the soffit vents from the outside in order to have proper ventilation.










3.Install a ridge vent on both roof tops in order because this is needed alongside soffit vents for this ventilation system to work.










4.Block off both gable ends as these do not work with soffit vents, and are, therefore, creating a short circuit effect on my soffit/ridge vent combo.











So I guess my question would be: why do I have gable ends and soffit vents to begin with if they are proven not to work properly togther... Seems a real genius built this house. I've only owned it since early 2006. It will be 3 years next month.


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## sunthas (Dec 29, 2008)

got any website that shows gable ends ruin soffit ridge vent systems?


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## 4just1don (Jun 13, 2008)

alot of this type talk in the roofing page,,,right here. Lots of roofers and experts on how and why's of doing what.

MOST say to take your soffit material(whether it is vinyl or alluminum material OFF and take off ALL soffit plywood "completely"and reinstall continous vented soffits AFTER making sure rafter bays are open and air flowing with aid of styrofoam baffles,,,then your ridge vents work right AND block off any gable vents!! Most guys there say the mushroom style or turbine style vents dont really work worth a hoot.


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## Wildie (Jul 23, 2008)

Here's a good article about ventilation! Very informative!

http://www.cmhc-schl.gc.ca/en/co/maho/gemare/gemare_001.cfm

Consumers > Maintaining a Home > General Maintenance and Repair > Attic Venting, Attic Moisture and Ice Dams ​ The following fact sheet is part of the About Your House — General Series




*Attic Venting, Attic Moisture and Ice Dams*

It is rare for Canadians to visit their attics. For many years building codes have required high levels of attic insulation, making attics less-than-hospitable places. People usually go into their attics for one of two reasons: animal intruders, such as bats or squirrels, or water leaking through the top floor ceiling. This guide deals with water entry, such as roof leaks, ice dams, and attic condensation. Consult your local pest control expert to rid the attic of creatures.


*Where to look for leaks*



around plumbing stacks or plumbing walls
chimneys through the attic
any light fixtures from the ceiling below
electric wiring
ducting for fans or heating systems
perimeter walls
partition walls
party walls
above pocket doors
above lowered ceilings
where the side of a cathedral ceiling meets an open attic
split level discontinuities
where additions meet an older section of the house
above rounded corners or staircases
balloon frame walls
 







Figure 2: Leakage areas on split level houses​ *Attic Venting*

If you have *properly sealed* the attic you should *not need more attic ventilation*. *Attic ventilation is overrated.* 

Recent research shows that identical attics, with one unvented and the other vented to code, have much the same humidity and temperature. Attic computer models show that attics in damp coastal climates may actually be drier with less ventilation.
*Building codes require attic ventilation. Ventilation may make a difference in a borderline situation.* Attic ventilation is driven primarily by wind. To ensure thorough venting, have openings at the soffits and then higher on the roof at the ridge, gable end, or high on the roof surface. The requirement for attic vent *sizing is nominally 1:300 *


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## Andrew Whitehead (Dec 31, 2008)

Don't forget, attic ventilation is also for summer, to keep the heat down in the attic, which keeps the house cooler as well as prolongs the life of your shingles.


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## sunthas (Dec 29, 2008)

Wildie said:


> Here's a good article about ventilation! Very informative!
> 
> http://www.cmhc-schl.gc.ca/en/co/maho/gemare/gemare_001.cfm
> 
> ...


This is a crazy article. Not sure I buy that you don't need any ventilation. or as they said: "with one unvented and the other vented to code, have much the same humidity and temperature." crazy.


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## 4just1don (Jun 13, 2008)

There are OTHERS who say inadequate attic vents lead to 'cooking ' the shingles from below,,alot like frying a egg on it, they claim much reduced shingle life.


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## Chemist1961 (Dec 13, 2008)

I live in Canada, but haven't read this info.

We currently have federal and provincial rebates for increasing attic insulation to a max of R50. The ECOENERGY website and others I have been to discuss the house as a system, as in attic ventilation as a system.
I have lived here in -55 F winters and + 100 F summers and I am now nestled between the Great Lakes. My shingles baked on the west side of my house within 12 years with only 3 roof top vents and underspec soffit ventilation for my 700 foot attic. In addition my top floor was an oven in the summer, cool in the winter. Although I don't visit there much but I can assure you on a hot summer day prior to improving the rooftop venting it hit 130 degrees. Because we ahve basements we don't inhabit most of our attics nor put much HVAC stuff up there
Ice dams continued to form on my East facing valleys until I upgraded insulation and increased soffit ventilation in my plywood soffits and added baffles between the rafterslast month. We have had in excess of 24 inches of snow since Dec 24th and NO ICE DAMS.

BTW over the December billing period my gas consumption in cubic feet has dropped by 25% over last year same period with SAME AVERAGE temp, Same programable T stat , same settings with same MID E furnace. So IMHO this stuff works.

I am offering several remaining well baked shingles found on my last visit to the atticfree to any doubters, you pay the shipping.


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## Chemist1961 (Dec 13, 2008)

Forgot to mention, the roofers said an under ventilated attic would fail to qualify for any warranty claims on the new 40 year shingles....


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## Baron (Jan 6, 2009)

Andrew Whitehead said:


> if you are getting that much condensation in your attic, did you make sure that you had a proper vapour barrier down before you had the insulation blown in? If not, the insulation maybe slowing the heat loss, but he moisture is still going through the same as before, if not faster since the inside of your house is warmer.


It is not wise to put any vapor barrier in an attic. Moisture rises and it is supposed to be allowed to leave the house as being contained it will cause problems. The basement under the slab and on the walls is the only place to install a vapor barrier. Proper venting will carry the moisture away. Gable vents aren't as good as ridge venting because they can't remove enough air in a constant flow across the underside of the roof sheathing to really do the job that is needed.


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## earthad1 (Apr 1, 2008)

Baron said:


> It is not wise to put any vapor barrier in an attic. Moisture rises and it is supposed to be allowed to leave the house as being contained it will cause problems. The basement under the slab and on the walls is the only place to install a vapor barrier. Proper venting will carry the moisture away. Gable vents aren't as good as ridge venting because they can't remove enough air in a constant flow across the underside of the roof sheathing to really do the job that is needed.


I've read the same information about vapour barriers in attics somewhere, and it makes sense to me not to have them. but I've also read where you can have them, so its conflicting information I guess.


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## Baron (Jan 6, 2009)

oops, double posted


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## Baron (Jan 6, 2009)

You can't. They spent a good part of the early 60's putting plastic everywhere when they thought electricity was going to be cheap. The power companies recommended a total encapsulation and would give you a free water heater if you installed electric heat and insulated their way.
In New England, where this occurred, they then spent the next few years actually cutting out the attic plastic vapor barrier and installing thicker insulation, due to the moisture build up and dampness created. 
People who had the moisture barrier were running the temps in their homes over 74 degrees or higher to burn off the moisture before they discovered the problem.

Some solar energy people resurrected the idea again in the 70's and 80's with no idea what they were doing. 

In remodeling I have been repairing the wall base shoe on some homes that is totally blackened from condensation in walls. I suspect plastic is actually just as good at containing moisture in walls as it is at keeping it out. I am pretty sure plastic sheets don't know what side the moisture is suppose to be on.


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## Wildie (Jul 23, 2008)

I would just like to say that the link that I posted, is to the Central Mortgage and Housing Corporation, owned and operated by the Government of Canada. Their recommendations will be used to formulate future building codes! The horse's mouth, so to speak! Its my understanding, that their research has shown that venting has little or no benefit for roof longevity! However, I just had a new roof installed, and paid for additional venting to be installed in both the soffits and at the ridge! http://www.cmhc-schl.gc.ca/en/co/maho/gemare/gemare_001.cfm


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## Baron (Jan 6, 2009)

Venting barely affects the temperature in roofing materials so that is true. But moister causes rot and mold in the framing of a structure and that venting addresses.

Maybe in Canada the moisture content from the ground is different. New England is very damp as the ground water is prevalent. 

Arizona would be wholly different, so advice or knowledge would apply differently there also.


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## Chemist1961 (Dec 13, 2008)

I understand the debate Barrier versus none. I was in a new show home attic last week, with plenty of blown insulation R40 I'm sure. There was condensation above the barrier when I reached down to pick up my flashlight. It was about -3 that day. So what happens with the condensation with no barrier? Is it supposed to suck into the ceiling behind the paint and cause no damage.?????


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## Baron (Jan 6, 2009)

So if I understand you correctly you have plastic film over the insulation in your attic that has puddles on it?

The theory is condensation vapors from your house atmosphere mainly rise with the heated air, warm air can support more moisture than cold air, and when it reaches colder air that can not support that moisture it drops off. 

If the attic isn't vented properly the moisture hangs on things, rafters, sheathing and insulation. Obviously if you have moisture being contained by a barrier, or not getting out the vented attic, the moisture drops off and works its way back into the environment in what ever way it wishes, caused by a condition barrier or physical barrier.

If you have moisture on top of the barrier in an attic, your attic is saving moisture some how. I would wonder if it was because of the barrier, as insulation doesn't prevent moisture passage but plastic does.

Very cold air may be the barrier too and the plastic is catching the moisture as it falls out of the attic atmosphere. A good debate I am sure but moisture prevention is done in the basement and limited in the living environment and the rest is exhausted as best as possible from the attic.

At least that is the theory. Conditions in each environment create different solutions and problems, so often times there will be a case of reverse logic that some times has a positive affect.

An attic is not a dehumidifier so attempts to alleviate an over abundance of acquired moisture from below creates its share of problems. The best bet is always to prevent all gained moisture other than living condition moisture, such as breathing cooking and water usage, below the cellar slab. Then the only moisture to remove is minimal. If there is no plastic under the foundation, and you live on earth, there is a great likely hood that your spot upon it is evaporating moisture continuously into your habitat that you are trying to pass through an attic vent with little condition adjustable abilities. 

I can only say that if what you are doing keeps the moisture out of the insulation and leaves it in a place that the attic can deal with it, in a way that doesn't harm the structure, then what you are doing may as well be right for your conditions.:thumbsup:


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## Chemist1961 (Dec 13, 2008)

*MISINFO see NRcan.gc.ca and energy star and R2000*

Baron, the condensation I found was above the barrier, below the blown insulation. No forst on the underside of the roof.
Wildie, it is *Canada* Mortgage and Housing Corp and *CMHC* doesn't indicate which way we're headed. _*They are a mortgage loan insurance provider....*_
Ontario building code requires a vapour barrier, generally.... 6 mil, sealed with acoustical sealant or red contractor tape on all insulated exterior walls, ceilings, etc. installed on the warm side of insulation. New construction must pass inspection for insulation and barrier before drywalling.There are exceptions where spray foams, etc are being used.
We are also building super energy efficient homes under the Energy Star and R2000 ratings/guidelines. These utilize a much tighter ENVELOPE approach and promote specific material requirements for air seal, etc...


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## Wildie (Jul 23, 2008)

earthad1 said:


> Hmmm, interesting... Could this be why my soffit vents may be sealed off? Because I have 2 gable vents???


 It quite likely! Its akin to having a bucket with a hole in the side,only upside down.


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## Wildie (Jul 23, 2008)

Chemist1961 said:


> Baron, the condensation I found was above the barrier, below the blown insulation. No forst on the underside of the roof.
> Wildie, it is *Canada* Mortgage and Housing Corp and *CMHC* doesn't indicate which way we're headed. _*They are a mortgage loan insurance provider....*_
> Ontario building code requires a vapour barrier, generally.... 6 mil, sealed with acoustical sealant or red contractor tape on all insulated exterior walls, ceilings, etc. installed on the warm side of insulation. New construction must pass inspection for insulation and barrier before drywalling.There are exceptions where spray foams, etc are being used.
> We are also building super energy efficient homes under the Energy Star and R2000 ratings/guidelines. These utilize a much tighter ENVELOPE approach and promote specific material requirements for air seal, etc...


 I stand corrected! I guess that I have revealed something of my antiquity. If my memory serves correctly ( and it can be doubtful at times) it used to named Central M..... 
The sneaky bu******rs changed the name without telling me! [grin] I know it was renamed, as I have one of their books, with the old name on it! :furious:

_Canada Mortgage and Housing Corporation (CMHC) is Canada's national housing agency. We are committed to helping Canadians access a wide choice of quality, affordable homes, while making vibrant, healthy communities and cities a reality across the country. CMHC works to enhance Canada's housing finance options, assist Canadians who cannot afford housing in the private market, *improve building standards and housing construction, and provide policymakers with the information and analysis they need to sustain a vibrant housing market in Canada.*_


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## Chemist1961 (Dec 13, 2008)

*Wildie here's what I know about CMHC from personal experience*

*CMHC* does provide insurance for our (non private) banks on higher ratio loans beyond 75%. In doing so they also may inpsect a home internally to insure it's value for the lender. My first purchase was approved with a drive by as I had just over 22% for a larger home.
They didn't come in and discuss my aluminium wiring so what kind of information and *anal*ysis is that? 
Anyway I don't think I would be reading their old books for qualified informed info... They did not come in and locate the 42" missing from my sill plate adjoining my garage, nor the 12' gap by 8" of missing plywood on my garage wall in the attic  opening into my formerly drafty kitchen bulkhead, so like any DYI fanatic, I stumbled across them myself. Granted this was a quality home and codes were different when it was built as were inspections and its in an upscale neighbourhood ......so I was a VERY safe loan. But does this sound like someone with building industry knowledge?


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## sunthas (Dec 29, 2008)

We know buildings have to be built different in different climate zones. Some places have different problems with cold and moisture than other regions. Which ever problem is your primary concern drives how you build your house.

My current understanding of the basic concept is you build your house so the living space is a tight controlled space. You attempt to control air coming into and leaving this space as much as possible and you attempt to control the temperature in this space as well. 

If you had a ceiling of drywall, then plastic vapor barrier, then studs, then R-40 insulation then open space then roof rafters then a vented roof... and you found water on the attic side of the vapor barrier then it must be dripping down into that space, it can't condense on the vapor barrier because the barrier should be the same temperature as the room below it. If the moisture was on the ceiling side of the vapor barrier then you could have water problems inside your room, that would indicate that you are venting your living space adequately. 

This system seems to work best in Very Cold and Cold climates. I'm not sure the vapor barrier is as useful when you get into the drier western zones of those climates. The vapor barrier is very helpful in containing air and keeping warm air from leaving through cracks. 

http://www.buildingscience.com/search?SearchableText=vapor+barrier

all kinds of good stuff.


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## Chemist1961 (Dec 13, 2008)

*Great stuff*

You're right, thats from right here where I live litterlaly 2 blocks from my house. Saw this before but lost the link.:yes:


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## Wildie (Jul 23, 2008)

Chemist1961 said:


> *Wildie here's what I know about CMHC from personal experience*
> 
> *CMHC* does provide insurance for our (non private) banks on higher ratio loans beyond 75%. In doing so they also may inpsect a home internally to insure it's value for the lender. My first purchase was approved with a drive by as I had just over 22% for a larger home.
> They didn't come in and discuss my aluminium wiring so what kind of information and *anal*ysis is that?
> Anyway I don't think I would be reading their old books for qualified informed info... They did not come in and locate the 42" missing from my sill plate adjoining my garage, nor the 12' gap by 8" of missing plywood on my garage wall in the attic  opening into my formerly drafty kitchen bulkhead, so like any DYI fanatic, I stumbled across them myself. Granted this was a quality home and codes were different when it was built as were inspections and its in an upscale neighbourhood ......so I was a VERY safe loan. But does this sound like someone with building industry knowledge?


 Some how, I'm given the impression that you think that I espouse CMHC. I would direct your attention to where I stated that I personally, chose not to follow their direction, and had ventilation installed according to conventional wisdom! My intent was to give the original poster a web page, where he could gain some knowledge about his problem and nothing more! Somethings change with time and some things do not! I'm quite aware of all the wonderful advances that have be made in home construction and how its considered best to have a closed environment. Never the less, its all not coming up roses! We now have air quality problems, that we didn't have when we lived in drafty old house's with inefficient octupus gravity furnaces etc. There's a real possibility that our families health has been compromised, in the name of saving a couple of bucks! As witnessed by the OP's problem in the attic, which has a real potential to turn into a mold problem that could be bad for his health! Have we advanced?


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## Baron (Jan 6, 2009)

I have seen three generations bring changes into home climate, trying to convince people to create a controlled environment and use electric devises to eradicate moisture and move air that would have "naturally" flowed through the house. If it were built in consideration to humans and not to some ecological fantasy and religious desire to create atonement to a cause by code enforcement, i would perhaps be less cynical.

However I have seen no evidence in New England in 30 years that plastic enveloping a house can work without a huge amount of electric devices running to control and otherwise natural process. 

Biological substances and spores need moisture and stale air to microscopically attack your home which is made of natural things. 

I know of a Doctor who developed a nasal conditioned gained from his own habit of storing fire wood in his damp cellar. His condition shortened his life and was preventable with ventilation or not storing wood in his cellar. 

I meet many people who have developed asthmatic conditions living in musty homes that have been built to code. I am not impressed with this latest push to force bubble living onto an unsuspecting public.

Stagnating water and damp conditions are products of the plastic envelope construction that has a higher cost to maintain due to the need to dehumidify are circulate air with exhaust fans. Why is money spent to dehumidify or expel more saintly then money spent for heat?

Again this is the third generational attempt I have been witness to, where marketers have tried forcing climate control construction that relies on electric devises to regulate interior living habitats, with poor health results as an acceptable sacrifice, all in the name of a political movement and not practical sense.

It didn't work positively in the 60's, again in the 80's and now we are seeing it mandated by code, with no consideration for its affects on health, building materials or long term value, and ignorant of its poor track record to boot.


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## Chemist1961 (Dec 13, 2008)

Wildie, I am sorry, didin't mean for my comments to offend you. They were meant to be directed toward the website. Let's just say, I think CMHC overstates their purpose and are not a resource most people I know would be looking to beyond insurance.
Although I too have sealed my attic holes and wiring etc and patched my vapour barrior I think Baron makes some excellent points. It would seem we should be building our homes with a Goretex like material as an air barrier. One that allows moisture to exit one way but stops draft and moisture from enterring? Is that correct? Traditionally our barriers have been on the warm side but a breathable one placed inside could trap moisture within the wall cavity so how would that be resolved?
With the little I know about Tyvek and newer building wraps I think the industry may be headed that way however that does not solve the issue of fresh air venting in naturally in an otherwise airtight space. And is there one good material for the variety of conditions we see across North America.
Has anyone got any feed back on how the Europeans handle this in their new home construction?


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## Wildie (Jul 23, 2008)

Sorry to hear about your less than satisfactory experience with CMHC! Perhaps your deficiencies should have been picked up by your home inspector, as CMHC's interest is more financially focused! Anyway, nuff said, as I suspect that we are in danger of hijacking this post. Getting back to vapor barriers! The whole idea is to prevent warm, moisture laden air from contacting cool surfaces, where the moisture will condense and cause damage! Its basically a simple concept, that doesn't require new technology or concepts. Our present methods are functioning well, in millions of homes!


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## earthad1 (Apr 1, 2008)

Just an Update to this thread:

So I had the insulator come back to start installing True vents in the attic. My initial plan was to replace the soffits, but upon further inspection, they are ALL clear. Nothing is blocking them from venting. The soffits are open throughout. We also noticed that I DO have ridge vents (I just thought it was some sort of grey tarp-like material they placed when putting the shingle cap in 2002, but it's actually a form of wire-meshing) 

The frost is most prevalent near the soffits themselves, indicating that the air is not flowing up to the ridge vent properly.




















































My Theory:

As stated before, I have 2 gable ends in the High attic, where the moisture is worst, but none in the lower attic where the moisture is far less prevalent. So when they installed the ridge vents, they did not block off the gable ends, causing a cross-circuit by having TOO much cold air entering the attic from the soffits and now from the gable ends. So there is so much cold air up there, its not really moving, which is causing the coldest air to sit near the soffit openings and frosting up.


Solution: Blocking off the gable ends and having TrueVents installed to guide the air up to the ridge vents.

Make sense?


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## Wildie (Jul 23, 2008)

earthad1 said:


> Just an Update to this thread:
> 
> So I had the insulator come back to start installing True vents in the attic. My initial plan was to replace the soffits, but upon further inspection, they are ALL clear. Nothing is blocking them from venting. The soffits are open throughout. We also noticed that I DO have ridge vents (I just thought it was some sort of grey tarp-like material they placed when putting the shingle cap in 2002, but it's actually a form of wire-meshing)
> 
> ...


 Studies made here in Canada have shown that gable vents should not be used in conjunction with soffit/ridge venting!
Congrats! You have just re-invented the 'wheel'! (grin)


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## earthad1 (Apr 1, 2008)

Wildie said:


> Studies made here in Canada have shown that gable vents should not be used in conjunction with soffit/ridge venting!
> Congrats! You have just re-invented the 'wheel'! (grin)


Apparently not all roofers are aware of that known fact. :laughing: 

I am also in Canada (NB)

God I hope this fixes the issue. I'm running out of options/ideas...


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## drtbk4ever (Dec 29, 2008)

Two years ago we had a contractor blow in some more insulation in our attics to bring it up to around R50. We don't have ridge venting on our house (I have never even seen it in Alberta), but rather roof vents situated on the roof itself. 

What we did is closed off all those roof vents except for one where we installed one of those wind turbines. The contractors theory is one wind turbine will move a lot more air than all those vents combined and if we leave the other vents open, the air the turbine pulls out of the attic will be replaced by air comingin the vents, not from the soffits.

Needless to say, we have do ice dams. I can't speak to the frost inside the attic as I don't go up there.

You guys have any comments on this? As I was thinking one of those wind turbines would help with the OP's attic ventilation. 

Oh I see he does have a roof vent.


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## earthad1 (Apr 1, 2008)

drtbk4ever said:


> Two years ago we had a contractor blow in some more insulation in our attics to bring it up to around R50. We don't have ridge venting on our house (I have never even seen it in Alberta), but rather roof vents situated on the roof itself.
> 
> What we did is closed off all those roof vents except for one where we installed one of those wind turbines. The contractors theory is one wind turbine will move a lot more air than all those vents combined and if we leave the other vents open, the air the turbine pulls out of the attic will be replaced by air comingin the vents, not from the soffits.
> 
> ...


Yup I already have a ridge vent so I'm thinking them not closing off the gable ends when they installed it was a mistake...

I've heard those turbines don't really do a good job, but I've never had one anywhere I've lived so I don't know.


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## Wildie (Jul 23, 2008)

Jon Eakes has written an article about venting in Canada and the use of power venting.
Here's the link! http://joneakes.com/cgi-bin/getdetailscals.cgi?id=628


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## earthad1 (Apr 1, 2008)

Wildie said:


> Jon Eakes has written an article about venting in Canada and the use of power venting.
> Here's the link! http://joneakes.com/cgi-bin/getdetailscals.cgi?id=628


Great article. Thanks for that...

Printed and will show to the insulation contractor tonight.


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## drtbk4ever (Dec 29, 2008)

Great article. He sure craps on my wind turbine set up. I guess I just need to make sure I have very little moisture exiting the living space. So I will have to venture into the attic and look for frost.

Damn I wish I had done this before the guys blew in all that extra insulation.


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## earthad1 (Apr 1, 2008)

drtbk4ever said:


> Great article. He sure craps on my wind turbine set up. I guess I just need to make sure I have very little moisture exiting the living space. So I will have to venture into the attic and look for frost.
> 
> Damn I wish I had done this before the guys blew in all that extra insulation.


I'm thinking the same thing...

I'm now also thinking of removing the louvers for my Air Exchanger and putting in some caulking where the louver meets the ceiling. I'm thinking that may be a source of moisture...

What about light fixtures? I know you're not allowed to put anything in the junction boxes where the actual wiring is... but should I seal up around the box, between the ceiling drywall and the box with caulking/Foam.


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## earthad1 (Apr 1, 2008)

So I now have those gable ends sealed up with some plywood and caulking. I also installed insulated hose going from the bathroom fan out into one of those dryer vents with the flaps, which is mounted into the center of one of the plywood sheets used to seal the gable ends. 

Now, my last task is to remove the air exchanger that is up there which no longer works because its dripping :furious:. I just noticed last night. 

I'm concerned about 2 things.

1. I'm not sure how the electrical cable to this thing is connected, whether it's like a plug or not and if I can simply "disconnect it" like a plug. I could turn off the breaker that is feeding the current to it, but I'm not sure if it was connected to it's own circuit, or if it is on the same circuit as other electrical devices in my home which I need.

2. The 2 insulated hoses connecting to this thing are still connected to vents going outside so cold air is coming into the unit and causing condensation since the unit is broken and therefore not running, which is dripping out of the corner of the unit onto the recently blown-in insulation. So I placed 2 buckets in each corner that its dripping from as a way to keep the water off the insulation while I figure out how to remove this ****ing thing.

So I'm thinking... Disconnect the hoses from the vents.... Seal the vents up with duct tape for now. Shove some batten insulation into the insulated hose, and then remove the unit from the attic.

I have a new, more efficient whole house fan which is also a heat recovery unit. The only problem is that it's too large to fit in the attic hatch. So this summer, I'm going to have to cut open the roof, between the frame as to not cut into one and get the unit in the attic that way...Then reconnect the hoses, open the vents back up ect...

Anyone have any suggestions which may make this a bit easier?

Thanks.


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## earthad1 (Apr 1, 2008)

So yea, I just went up on the roof and noticed both ridge vents completely blocked off by snow and ice. So I removed the blockage.

I'm thinking these things won't work well or at all if they are not constantly clear since snow acts as an insulator. 

Therefore, being that we get a crapload of snow here, how am I going to ensure my ridge vents remain clear during the winter? Heat cables?


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## earthad1 (Apr 1, 2008)

So we removed the air exchanger and all the duct work as well since they were FULL OF WATER AND MOLD!!!!!!!!!!

no traces of mold anywhere else but in the ducts...

I'm going to shove pink insulation in the ceiling cavities where the ducts came out, followed by a layer of foam insulation, patch is up with drywall compound, put the louver back so it "looks" like there is something there, and finally seal the screw heads with silicone to ensure no air leaks caused by the screws. I have textured ceilings, which is why I'm putting the louvers back on.

Anyone see anything wrong with this plan?


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## earthad1 (Apr 1, 2008)

does anyone at all have some advice in regards to my last few posts?


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## earthad1 (Apr 1, 2008)

Hi everyone,

Its been about 2 years since I posted in this thread and I have an update. 

Just to recap. I had 2 gable ends that I sealed up because I have a ridge vent. I then had insulation blown in and placed true vents to guide the cold air up to the ridge vent. I also insulated and sealed the attic hatches by gluing a piece of batten insulation to the top of the hatch, and lining it with foam insulation. I then placed hooks underneath so that when I close the attic hatch, it makes a seal.

I went up there yesterday to perform a visual inspection. It was -1 degree Celsius when I went up.

It "seems" pretty well dry up there. The insulation feels nice and dry but it feels to me that the sheathing may be still a little damp. Also, I noticed some frost on the edges of both sides where the gable ends are sealed up and the insulation directly below is is damp but the floor is bone dry.


































My ridge vent is covered in snow but I've been told that the attic can still breath even though its covered.

Anyone have any ideas why I STILL have frost up there? Lack of ventilation now? Exterior seams not insulated properly. I'd like to get this damn thing fixed once and for all this spring.

Any help is greatly appreciated!!!!

Thanks!


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## Wildie (Jul 23, 2008)

It appears to me that water is coming through the roof above the gables. 
Is the roof in good shape above this, or perhaps the ridge vent is short of the fascia and isn't sealed in a way that prevents water from entering?
You haven't shown the soffit venting in these pics.
I would think that you need to have some method of keeping the insulation blocking the flow from the soffits.
Frost forming on the underside of the roof sheeting is a sign of warm, moist air infiltrating from inside the house.
It may be coming into the attic by way of electrical boxes in the ceilings below.


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## earthad1 (Apr 1, 2008)

Wildie said:


> It appears to me that water is coming through the roof above the gables.
> Is the roof in good shape above this, or perhaps the ridge vent is short of the fascia and isn't sealed in a way that prevents water from entering?
> You haven't shown the soffit venting in these pics.
> I would think that you need to have some method of keeping the insulation blocking the flow from the soffits.
> ...


Thanks for the reply Wildie.

The roof seems to be in good shape, and that's what I'm hoping is not happening, but I agree that it does look like water seepage then turning to frost. But its on both sides. 

There is a gap between the ridge vent and the end of the roof. (I'd say about 1 1/2 feet on each side)

I've sealed off the attic hatch quite well (if you look at the older pics, you'll see frost above the hatch, now there is none) the frost used to extend all the way up to the ridge vent. Now, it seems prevalent near the soffit openings. There is none near the top of the attic but the wood did feel damp (though I don't know if that's the cold making it feel damp to my touch or that its actually damp)

I had the contractor who blew in the extra insulation add insulation to block off the soffits and placed those foam true vents in an attempt to guide the cold air from the soffits up sheeting and out the ridge vent. He checked and confirmed the soffits are not being blocked by insulation. Even though this has been installed, it still doesn't seem to be working.

So I'm going to need to lift the batten to looks for these electrical boxes. I don't have recessed lights. I have 3 bedroom lights, and hallway light the bathroom light it mounted to the wall, not the ceiling. There is a metal pipe in my son's room that used to feed duct work that ran into the attic when my air exchanger was up there... All that has been removed. I'm going to remove that pipe and seal/insulate the hole going into the attic as this may be a source of heat loss into the attic.

Being that the frost is so low, near the soffits, to me, it appears like the air is just not flowing properly. 

I have a lower attic, but I haven't checked it yet. Its never given me as many problems as this one has. The lower attic consists of the kitchen and the living room. The upper attic consists of 3 bedrooms and a bathroom.

My bathroom fan venting out to the sealed gable in an insulated duct.










Another shot of the truevents










What do you suggest to use to seal off air leaks? Expanding foam insulation? I have a full can of "Great Stuff" kicking around somewhere.


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## wilsonstark (Jan 16, 2011)

Where does the condensed water from the exhaust fan go? It's my understanding (and I admit I'm no expert) that you want to have the initial upward travel of the vent to go high enough that any water that condenses will trickle down and out of the house rather than sitting in the pipe or dripped back down into the house or attic? That looks like a direct path upwards and then curving to the vent. I suppose if it is short enough to stay warm you might not have a water problem from condensation, I'm sure that insulation helps a lot?


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## earthad1 (Apr 1, 2008)

wilsonstark said:


> Where does the condensed water from the exhaust fan go? It's my understanding (and I admit I'm no expert) that you want to have the initial upward travel of the vent to go high enough that any water that condenses will trickle down and out of the house rather than sitting in the pipe or dripped back down into the house or attic? That looks like a direct path upwards and then curving to the vent. I suppose if it is short enough to stay warm you might not have a water problem from condensation, I'm sure that insulation helps a lot?


no you're right, I need to figure out a way to mount it so it travels down... currently it runs alongside the attic floor and then goes up to vent... not the right way.

I just called a roofer and he said my frost is being caused by my ridge vent being blocked off by snow and its not breathing.... I'm thinking this is not the problem... though we've had HUGE amounts of snowfall this year... I guess it would not hurt to go up and remove it all? My issue with this is that he's pretty much saying a little frost is normal when I know for a fact that its not!


EDIT: _In regards to the duct, how would I do this? if the duct enters the attic at a lower point than the exhaust, what's the best configuration to have it trickle out the gable end?_


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## wilsonstark (Jan 16, 2011)

EDIT: _In regards to the duct, how would I do this? if the duct enters the attic at a lower point than the exhaust, what's the best configuration to have it trickle out the gable end?_[/QUOTE]

Attaching a very simple picture. Someone correct me if I'm wrong, but I understand the best way is to use rigid duct work with a straight run up and a sloping straight run slightly downward to the exhaust port. Install it, put in supports as needed, tape the joints and then get that insulated sleeve back overtop of it.

Regardless of the exact shape, I gather the core principals are a) Keep resistance to a minimum (use rigid pipe not flexible), b) As few turns as possible (each one dramatically reduces drag, although not as much as using flex duct) c) make sure you're sloping downward with as few turns as possible before it is going to start to condence.


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## earthad1 (Apr 1, 2008)

This is how I have it currently










Needs to be the opposite. Use wire and give it a slow grade up, then back down into the exit?

EDIT: I'd be worried water would run back down into the bathroom fan


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## wilsonstark (Jan 16, 2011)

earthad1 said:


> This is how I have it currently
> 
> 
> 
> ...


The air is warmest the closest to the fan, and the pipe will be warmest as well. As long as your horizontal run is downward sloping I can't imagine any water coming down the fairly short vertical run from the fan. Much more importantly none will be sitting in the horizontal run, growing icky stuff.


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## earthad1 (Apr 1, 2008)

Like this?


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## wilsonstark (Jan 16, 2011)

Steepest possible up slope that still allows just one elbow and a gradual slope downwards. I don't have a paint program on my phone might try to do it later.


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## Wildie (Jul 23, 2008)

earthad1 said:


> Like this?


 The optimum way to run the bath ductwork is to run it verticly as possible from the fan, to a point slightly higher than the gable vent. Then, run it downhill to the vent.
The idea being that any moisture from the bathroom that condenses, will run out the gable vent, rather than back into the fan.
In my home the fan is vented verticly, all the way out through the roof and I have never experienced a problem with it.
Its a only a 4 foot run, so I assume that the moisture laden air is vented before it condenses.

As for the frost that is still forming, perhaps the ridge venting isn't adequate and you may require a couple of mushroom vents to suppliment it.


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## mem (Dec 15, 2010)

Looks to me that your true vents are not done properly. The insulation on either side of them is blocking potential ventilation air from your soffit vents, apparently by as much as 50%! The true vents should be installed across the full width of the rafter bays to ensure maximum draw from your soffits.

Also make sure your soffit vents are adequately sized. Around here it needs to be a minimum of nine square inches per foot of net free vent area. Exceeding the minimum here will do no harm. The idea is to make the soffit vents the easiest place for air to enter the attic to replace that which escapes out the ridge. That guy with the drill in the one photo is just wasting time. Your ridge vent needs to be spec'd at slightly less that twice what the soffit vents are spec'd as the ridge vent services soffits on both sides of the house. The space seen in your sheathing for the ridge vent looks rather small for this. Keep in mind the material used for the filter in the ridge vent also takes away from net free vent area as well. If the soffit vents are constricted, as your are, make up air will be drawn in through the ceiling from your living spaces. This is also why the soffit vents should be slightly larger than the ridge vent.

A vapor barrier is essential, IMO, to prevent moisture from traveling up through the insulation. The top few inches of insulation are as cold as the rest of the attic and water vapor can condense on insulation as easily as on wood framing members. Damp or wet insulation severely reduces the R factor and takes forever to dry out, especially with inadequate ventilation. Ideally, the vapor barrier should be six mil poly sheeting installed directly behind the finished ceiling.


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## Gary in WA (Mar 11, 2009)

I agree with mem except on the vapor barrier. Find your location on page 26, read page 28; http://www.nuwool.com/pdf/VaporBarrierJournalPaper.pdf 

Your ridge vent is only ½ cut, as mentioned. The baffle is too small, compare to this 25 sq.in.; http://www.bergerbuildingproducts.com/pdfs/Berger_AccuVent_Attic_Vent.pdf from HD.
Or Lowe’s at 19- sq.in.- cut for 16”o.c. would be 9sq.in., the recommended minimum. http://www.adoproducts.com/duro.html Someone cut yours to the 16" size when they should have used them full width for 24"o.c.


Gary


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## wilsonstark (Jan 16, 2011)

Wildie said:


> The optimum way to run the bath ductwork is to run it verticly as possible from the fan, to a point slightly higher than the gable vent. Then, run it downhill to the vent.
> The idea being that any moisture from the bathroom that condenses, will run out the gable vent, rather than back into the fan.
> In my home the fan is vented verticly, all the way out through the roof and I have never experienced a problem with it.
> Its a only a 4 foot run, so I assume that the moisture laden air is vented before it condenses.
> ...


Agreed about going out through roof, at least in theory, but that has to be done REALLY correctly or frost is the least of your worries. For a DIYer I'd say at least temporarily avoiding more holes in your roof might be wise.

I've tried to illustrate the point for the OP. Again, go as straight up as you can while still leaving the horizontal pipe with enough fall for condensed moisture to drain out of the house.


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## earthad1 (Apr 1, 2008)

Wow, thanks for all the help on this guys!!! Your feedback is excellent and very much appreciated.

*


Wildie said:



The optimum way to run the bath ductwork is to run it vertically as possible from the fan, to a point slightly higher than the gable vent. Then, run it downhill to the vent.

Click to expand...

* Yea, I can get a vertical run by using the attic floor, but the gable is higher than the attic floor, that’s the hard part…so if I do as low as a slope as I possibly can, get it higher than the opening in the gable, then direct it downward out to the gable, it should work?

What if I run it vertically on the attic floor, cut out a circle in the soffit, and vent it out that way?

*


mem said:



Looks to me that your true vents are not done properly. The insulation on either side of them is blocking potential ventilation air from your soffit vents, apparently by as much as 50%!

Click to expand...

* I though you needed to block that off for those vents to work properly. Should I just remove that yellow insulation he put there?



mem said:


> *The true vents should be installed across the full width of the rafter bays to ensure maximum draw from your soffits.*


 
Those were the widest ones we could find…lol so you’re saying maybe double them up?



mem said:


> *Also make sure your soffit vents are adequately sized. Around here it needs to be a minimum of nine square inches per foot of net free vent area. Exceeding the minimum here will do no harm. The idea is to make the soffit vents the easiest place for air to enter the attic to replace that which escapes out the ridge.*


 My soffits are open all around the house. I’m going to replace these ones this summer when I replace the ridge vent with a higher quality one. I have the old machine punched aluminum soffits which don’t seem to be as effective as the straight hole punch ones (though would that not allow water to enter?) 



mem said:


> *That guy with the drill in the one photo is just wasting time. Your ridge vent needs to be spec'd at slightly less that twice what the soffit vents are spec'd as the ridge vent services soffits on both sides of the house. The space seen in your sheathing for the ridge vent looks rather small for this. Keep in mind the material used for the filter in the ridge vent also takes away from net free vent area as well. If the soffit vents are constricted, as yours are, make up air will be drawn in through the ceiling from your living spaces. This is also why the soffit vents should be slightly larger than the ridge vent.*


 I get it, so because my soffits are not working properly in drawing in the air from outside, my ridge vent is essentially sucking warm air from wherever it can from inside the house? Yea, now that you guys mention it, after looks at videos of people installing ridge vents, it seems that my openings are pretty small compared to what I’ve seen done.



mem said:


> *A vapor barrier is essential, IMO, to prevent moisture from traveling up through the insulation. The top few inches of insulation are as cold as the rest of the attic and water vapor can condense on insulation as easily as on wood framing members. Damp or wet insulation severely reduces the R factor and takes forever to dry out, especially with inadequate ventilation. Ideally, the vapor barrier should be six mil poly sheeting installed directly behind the finished ceiling.*


 I’ve been told that a vapor barrier between the attic floor and the home’s ceiling is a huge no no in my area.

Thanks for the links GBR in WA, I’m reading them now!

http://www.bergerbuildingproducts.com/pdfs/Berger_AccuVent_Attic_Vent.pdf

Definitely want these!!!!! So the idea is that they fit the entire width of the baffle and bend at the bottom eh? Cool! Wish I would have known about there. Would have saved me some $$$ in having this guy installed the wrong ones!!!!


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## mem (Dec 15, 2010)

earthad1 said:


> Wow, thanks for all the help on this guys!!! Your feedback is excellent and very much appreciated.
> 
> 
> 
> ...


I think you mean horizontally on the attic floor. And yes you can. Actually, this method might possibly be your best alternative. Just put a short straight section of duct vertically, tall enough so you can get a downward horizontal slope to the exhaust port. Keep the exhaust port in the gable end though, i.e cut a new hole. If you exhaust the vent near the soffits you run the risk of sucking that moisture right back into your attic through the soffit vents. 



earthad1 said:


> Quote:
> Originally Posted by mem
> Looks to me that your true vents are not done properly. The insulation on either side of them is blocking potential ventilation air from your soffit vents, apparently by as much as 50%!
> 
> ...


As GBR notes it looks like those baffles were cut in half to, unbelievably, save material costs. Get the plastic ones you like from the berger link he posted (and maybe a new installer?). They are easier to work with in a retrofit when the nails are protruding from the underside of the deck. And the downward flap on them will prevent your blown in insulation from falling back into the soffit and plugging them up in the future.

When you replace the soffit vents, opt for a continuous type vent. They ensure balanced venting along the entire soffit run and are regarded as the most effective.



earthad1 said:


> Quote:
> Originally Posted by mem
> A vapor barrier is essential, IMO, to prevent moisture from traveling up through the insulation. The top few inches of insulation are as cold as the rest of the attic and water vapor can condense on insulation as easily as on wood framing members. Damp or wet insulation severely reduces the R factor and takes forever to dry out, especially with inadequate ventilation. Ideally, the vapor barrier should be six mil poly sheeting installed directly behind the finished ceiling.
> 
> ...


Normally I would be reluctant to disagree with GBR on anything as his advice is typically spot on. In regard to the vapor barrier though, I don't understand why he is not on board. The link he supplied clearly states the need for a vapor barrier in your neck of the woods. See page 27, points 5 and 6, and the chart on page 28 as well.


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## earthad1 (Apr 1, 2008)

mem said:


> I think you mean horizontally on the attic floor. And yes you can. Actually, this method might possibly be your best alternative. Just put a short straight section of duct vertically, tall enough so you can get a downward horizontal slope to the exhaust port. Keep the exhaust port in the gable end though, i.e cut a new hole. If you exhaust the vent near the soffits you run the risk of sucking that moisture right back into your attic through the soffit vents.


Sorry, that's what I meant...:laughing:



mem said:


> As GBR notes it looks like those baffles were cut in half to, unbelievably, save material costs. Get the plastic ones you like from the berger link he posted (and maybe a new installer?). They are easier to work with in a retrofit when the nails are protruding from the underside of the deck. And the downward flap on them will prevent your blown in insulation from falling back into the soffit and plugging them up in the future.


Yup that's exactly what he did... Not knowing any better, I thought he did it properly.:furious:. They are just stapled in. Is that ok when I redo them? Just use staples ?



mem said:


> When you replace the soffit vents, opt for a continuous type vent. They ensure balanced venting along the entire soffit run and are regarded as the most effective.


I will thank you!



mem said:


> Normally I would be reluctant to disagree with GBR on anything as his advice is typically spot on. In regard to the vapor barrier though, I don't understand why he is not on board. The link he supplied clearly states the need for a vapor barrier in your neck of the woods. See page 27, points 5 and 6, and the chart on page 28 as well.


I'm in New-Brunswick, Canada, right above Maine (the border is about 2-3 hours) and I've never seen any newer homes used vapor barrier between the attic and the ceiling. I'll have to have a look and see though I'm like 90% sure this is nothing there. I was under the impression if you had one, if any moisture were to make its way up into the attic and his this vapor barrier, water vapor could then be deposited on the ceiling and cause damage to it.

Now, is a "Vapor Barrier" and a "Vapor Retarder" the same thing??


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## earthad1 (Apr 1, 2008)

After reading a bit more on this, I'm confused. So am I supposed to have a vapor barrier on the attic floor or not?

http://www.cmhc-schl.gc.ca/en/co/maho/enefcosa/enefcosa_002.cfm

"_Attic Insulation_ _The attic is often the most cost-effective place to add insulation. Usually, a contractor blows loose fill into and over the top of ceiling joists. For the do-it-yourselfer, batts laid sideways on existing insulation are an easy alternative._


_The air barrier at the ceiling line must be tight to ensure warm moist air from the house does not get into the cold attic and condense in the winter. Check ceiling light fixtures, the tops of interior walls and penetrations such as plumbing stacks for air leakage._
_Ensure that soffit venting is not blocked by added insulation; baffles may have to be installed."_

My house was built in 1978-1980 so I'm guessing that if I lift up the insulation that's in the attic, I'm going to see a vapor barrier?


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## Gary in WA (Mar 11, 2009)

Sorry I gave you the wrong idea in not being specific enough. I should have said- Check to see from the BSC site if plastic (Class 1) is required or just a Class 2, vapor barrier primer paint on the lid from below. In your case the plastic would be extremely hard to do..... after the fact. V.b. vs v.r.; http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11810

Is the frost at the sheathing/gable framing because the fan moisture is trying the exit and because it is colder there, condensing and freezing? 

Just cut a new bath fan hole lower down on the gable, just above the insulation. Run ducting up at the fan to get some fall over the rest of run for drainage. Be sure to insulate and v.b. the ducting, air seal all joints (even the individual elbow ones). Another option; http://homes.winnipegfreepress.com/index.php?action=news&step=article&id=702

Gary


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## mem (Dec 15, 2010)

Staples to hold the baffles is fine. They are lightweight and should stay put that way.

I believe you would be in a zone 7 climate and would need a vapor barrier. The vapor barrier would prevent moisture from making its way up into the attic in the first place, as long as it is air sealed well--which it sounds like you've done.

As the names imply, a vapor retarder merely slows down the migration of water vapor where as a vapor barrier blocks it nearly completely. The kraft facing on fiberglass batts is a vapor retarder and 6 mil poly is a barrier.

If you dig down thru your insulation and find a layer of thick plastic (≥ 6 mil) you have a vapor barrier. It would need to be the layer just above the finished ceiling to work properly (the warm-in-winter side of the insulation). I'm also curious as to how you are aware that newer homes in the area don't use a vapor barrier.


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## earthad1 (Apr 1, 2008)

GBR in WA said:


> Sorry I gave you the wrong idea in not being specific enough. I should have said- Check to see from the BSC site if plastic (Class 1) is required or just a Class 2, vapor barrier primer paint on the lid from below. In your case the plastic would be extremely hard to do..... after the fact. V.b. vs v.r.; http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11810
> 
> Is the frost at the sheathing/gable framing because the fan moisture is trying the exit and because it is colder there, condensing and freezing?
> 
> ...



Thanks Gary, and yes, it could be that the fan is not venting as well as I had hoped, and the vapor is getting trapped under the peak, condensing, running down and freezing. We don't use the bathroom fan all that often as I take showers in the bathroom downstairs and not this one, but heat would constantly be escaping. I'm thinking cutting in lower is a good plan... 

I was thinking, the fan is only about 2 feet from an exterior wall in the bathroom, I'll take a photo of the bathroom/wall and the one in the attic where the pipe comes in... I might be able to run it that way...much shorter distance.

There is frost on the other side of the attic also at the other gable, but its not as bad as the side with the fan venting out.

@mem: As far as the vapor barrier issue, I though I had seen some posts about that in this thread... I must be mistaken.

I'm thinking, looking back, the frost issue has been the poor installation of the ridge vent the entire time :-( 
If I think about this logically:

The house is about 32 years old. The roof was redone in 2003. Obviously, if this had been an issue the entire time, the roof would be rotten.

1-The insulation amount did not change.
2-The Soffit configuration did not change.
3-The attic hatches have not changed

The only thing that changed was the addition of this ridge vent and the fact they did not seal up the gables when they installed it.

AFTER the frost/moisture was discovered I:

1-Added insulation
2-Added the TrueVents and blocked off with insulation (now will remove)
3-Sealed up the attic hatches
4-Removed a leaky air exchanger and all the duct work. Sealed all louver holes into attic (4 of them)
5-Sealed the Gables
6-Re-routed the fan Duct from a soffit to the gable.​
For starters, I'm going to go up there this weekend, check for vapor barrier, and I'm going to remove those pieces of batten insulation that are blocking the baffles out to the soffits. Hopefully that increases the airflow up to the ridge vent and reduces the frost.

What do you guys think?

So in the spring, I'm going to hire a roofer to properly cut the ridge to the recommended size and install this type of ridge vent:  

http://www.airvent.com/homeowner/products/ridgeVents-shingleVent.shtml 

http://homehardware.ca/en/rec/index.htm/_/N-67lZ2pqf/Ne-67n/Ntk-All_EN/R-I2672281?Ntt=2672-281

and have him install these











I'll then install those continuous soffit vents around the entire house.


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## wilsonstark (Jan 16, 2011)

Just as a note, those things look pretty cool, but you can also make perfectly good channels of a similar type, precisely fitted to your attic using blocks of 2x2 (to space it off the roof sheathing) and either plywood or xps foam board. Might be more affordable and DIY. I know my roof has those and the sections I have had open to check have kept those channels clear for air to flow up quite nicely.


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## mem (Dec 15, 2010)

wilsonstark said:


> Just as a note, those things look pretty cool, but you can also make perfectly good channels of a similar type, precisely fitted to your attic using blocks of 2x2 (to space it off the roof sheathing) and either plywood or xps foam board. Might be more affordable and DIY. I know my roof has those and the sections I have had open to check have kept those channels clear for air to flow up quite nicely.


I'm sure that would work just fine as well, but it's got to be a ton more work with cutting, fitting and nailing up there. And you'll have at least four pieces to fit per bay! bizrate has the AccuVent listed at Home Depot for $1.68 each for the model that fits 24" rafter spacing. I don't see how you'll beat that with wood and/or foam. You can carry up a whole house worth in one trip, trim them if necessary with just a pair of scissors and tack 'em up with a half dozen staples--definitely a DIY job, maybe five minutes per bay if you're taking your time.


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## wilsonstark (Jan 16, 2011)

mem said:


> I'm sure that would work just fine as well, but it's got to be a ton more work with cutting, fitting and nailing up there. And you'll have at least four pieces to fit per bay! bizrate has the AccuVent listed at Home Depot for $1.68 each for the model that fits 24" rafter spacing. I don't see how you'll beat that with wood and/or foam. You can carry up a whole house worth in one trip, trim them if necessary with just a pair of scissors and tack 'em up with a half dozen staples--definitely a DIY job, maybe five minutes per bay if you're taking your time.


Wow. I can't argue, that's not big money price at all. Thought they'd be more


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