# Baffled over baffles



## Bud9051 (Nov 11, 2015)

Baffles need to extend from the soffit area to above the top of the insulation. There should be one in every channel as the air flow not only removes any moisture, it helps cool the bottom of the roof to stop snow melt.

As for using plywood, there is nothing special about the foam ones you have and people often use other materials, although I would avoid cardboard which i have see several times. An option is to install 1" foam spacers on each side and then use 1" foam for the baffle. It makes a nice unobstructed air path.

Bud


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## Alumifab (Jul 23, 2009)

So even though there isn't a soffit in every channel, there should be a baffle in every channel?


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## Bud9051 (Nov 11, 2015)

When you say there isn't a soffit, I assume you mean a soffit vent. With some construction methods all rafter channels are isolated from all others. But yes, assuming the soffit cavity is continuous it can and should supply ventilation to all rafter cavities.

Plus, it would be bad to blow insulation up against the bottom of the roof.

In addition, the baffles should provide a flap at the bottom to cover the end of the insulation from incoming air flow, it is called wind washing and it can actually blow the insulation away from the edge of the ceiling.

Bud


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## Alumifab (Jul 23, 2009)

Yes I meant soffit vents. I only have 2 one each side of the home.
I know not to cover the vents with insulation, but this looks weird as I just bought the home and am trying to figure out what the best approach is to fix it.


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## Bud9051 (Nov 11, 2015)

With a common soffit construction that cavity should feed all rafter bays. Then the question becomes, are those 4 vents providing enough air flow? Give me the area of your attic floor and the dimensions of those 4 vents. Plus, are they covered with a screen and louvers?

Then, what do you have for high vent area?

Bud


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## Windows on Wash (Aug 30, 2011)

Alumifab...how about some pictures of them. There can tend to be some miscommunication from time to time and a picture is worth a thousand words here.


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## Alumifab (Jul 23, 2009)

I apologize I'm wrong on the number of soffit vents. That's what I get for looking in the attic. 
I have 2 in the back, 1 in the front and 6 on each side. I can see in some areas where the top plate is exposed in the attic so I want to have baffles properly installed and then the insulation up against that, but not covering any soffit etc. 
here are some pics of the outside of home.


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## Bud9051 (Nov 11, 2015)

I'd estimate 6 ft² for 15 of those vents. That's 50% NFA.
Now, you should have something similar up top.

Bud


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## Alumifab (Jul 23, 2009)

Sorry I'm a newbie.
What's NFA??


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## joecaption (Nov 30, 2011)

Not even close to enough soffit vents or roof venting.
There's no reason to have anything "removed" just move it out of the way and and seal it, then push it back in place.
There's nothing wrong with foam baffles.


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## Bud9051 (Nov 11, 2015)

@alumi, NFA is net free area. An opening covered by screens and louvers will provide less air flow than the original opening, therefore they test and rate the vents with an equivalent vent area. The ratings will range from 80% down to 20% depending upon the design.

Joe, actually his soffit vents are close, we are working on determining what is up there for roof vents, TBD (to be determined).


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## Alumifab (Jul 23, 2009)

Ok, so here's what I can determine.
I only have 2 attic fans to release all of the hot air.
3 of the 6 soffits on one side are located over the garage which is not insulated, not sure if that makes any difference at all.
There also seems to be a mesh net on the inside of the soffits, maybe to keep critters out of? Not sure. I can't get close enough to get a good picture.
Here's a few more pictures.

I really appreciated everyone's' opinion.
Just trying to make my home as right as possible.....


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## Bud9051 (Nov 11, 2015)

Just passing by quickly, but the 3 vents in/over the garage should not be counted in the calculation for required vent area and the attic over the garage, unless properly air sealed from the space below, should be sealed off from the house attic.

I'll be back
Bud


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## Alumifab (Jul 23, 2009)

The attic over the garage is open to the blown insulated attic part......
Here are some pics where you can see the attic above the garage meets the insulated part of the home.....
If the vents over the garage don't count, then I have 3 vents on each of the 2 sides instead of 6.


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## Bud9051 (Nov 11, 2015)

Is the ceiling in the garage finished and sealed?
If so, then you can count those vents, but you must add the larger footprint to include the garage.

Bud


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## Alumifab (Jul 23, 2009)

Yes, but there is no insulation.
Is that what you mean by finished and sealed?


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## Bud9051 (Nov 11, 2015)

I was looking for air sealed as required by fire codes. It is a serious issue when exhaust from a vehicle can get pulled into the living space. A garage is usually sealed as to prevent that.

I'm guessing that it is closed off, you will have to judge whether it is sealed. But, is that area part of your total attic floor calculation?

Bud


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## Alumifab (Jul 23, 2009)

My home inspector didn't say anything about this, except to move the electrical lines away from the gas line.

I can say this, that the floor in the garage is going to get a nice bead of caulk as I don't think the floor is sealed as I do smell a little exhaust when I come in the home from the garage. Now that could be from the door when I'm entering, who knows.....

Too bad you guys aren't in Dallas, so you could help me......
but you are helping me from afar and I appreciate it!!


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## Bud9051 (Nov 11, 2015)

Gary should be along with the actual code, if required.

Bud


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## Alumifab (Jul 23, 2009)

There are a lot of homes in my neighborhood that have the same layout. Here's my neighbors roof line. Just like mine. Same floor plan. I know the homes were built by dr Horton but they refuse to give me the blue prints.


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## Alumifab (Jul 23, 2009)

Here's the other side of my roof. I have one vent on the back and 3 on this side. I think that's what the square boxes are attic vents??


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## Alumifab (Jul 23, 2009)

The dimensions of my home are 70' x 38' rough measure........
That does include the attic and porch.


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## Bud9051 (Nov 11, 2015)

OK, I went back and scanned through the thread and I'm not sure I totally have the picture. Here's what I understand and some terminology.

You seem to be mixing "vents over the garage" in reference to soffit vents. So try to differentiate between high and low vents.

With the 15 soffit vents I estimate you have sufficient low venting.

With 4 roof vents (high vents) you are far short of what is recommended at less than 2 ft². That is assuming 60 in² per roof vent.

I'm not sure where the fans come in, but they are not part of the static vent calculation. Tell me what these are.

Bud


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## Alumifab (Jul 23, 2009)

Ok, tomorrow, I will try to get everything straight. Sorry I saw vents and assumed they were all the same.
Not sure I have fans, but vents yes.

On a side not, as I'm driving around, I don't see a lot of attic vents on everyones' property. Are most homes under vented in the attic???


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## Bud9051 (Nov 11, 2015)

Some may have ridge vents which can be less obvious or the roof vents have been installed on the back side. In older homes it was common to not have good ventilation, but anything in the past 30 years or so should be reasonably well insulated. Current knowledge combined with airtight construction has changed how and what we do, but traditional ventilation is still very effective.

been a busy cold spell as people are just now discovering what they should have taken care of last summer, or in TX, spring or fall. Noone works in your attics in the summer .

Bud


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## Alumifab (Jul 23, 2009)

true, that's why since buying the home last month, I want to get the home as right as possible before the blazing heat in Texas melts everything, haha.


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## Alumifab (Jul 23, 2009)

Here are some pictures of the attic vents that I have, I assume they are just regular attic vents, nothing fancy.
Also, it's very hard for me to get close to the soffits to take a decent picture.
One picture is of my furnace pipe going through the roof.
Then one picture from my insulated area of the attic connecting to a uninsulated area over the garage.

At this point I am not sure what to do.
Do I have enough soffit vents?
Do I have enough attic vents?
Should I install a ridge vent?
Should I get a contractor to look at all this? Is it worth the money?

I guess welcome to home ownership 
:biggrin2:


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## Alumifab (Jul 23, 2009)

To me this how soffits and baffles should work, but I could be wrong. And if it is, how much would it cost to retrofit my house and is it cost effective..... Something I have to figure out, or I'm just way too anal about all this.......


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## Bud9051 (Nov 11, 2015)

That's one way, using a high density batt folded to block insulation from falling into the soffit. But a small amount of air will still seep through the folded batt. Your white baffles look like this: http://www.homedepot.com/p/Amerimax...u=202962730&ci_kw=&ci_gpa=pla&ci_src=17588969

This provides an air block as well as holding back the insulation. Available for 16" on center. Either way works.

Bud


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## Alumifab (Jul 23, 2009)

Ok thanks!

Now another stupid question :biggrin2:
Does every rafter section need a baffle even if there isn't a vent from below??


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## Bud9051 (Nov 11, 2015)

@ AL "Does every rafter section need a baffle even if there isn't a vent from below??"
Yes, the objective is to cool the bottom of the roof and move that heat out, not just provide a path for air to get into the attic above.

I am also assuming that the soffit space is common where a few vents will be able to provide air to all rafter channels.

Bud


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## Gary in WA (Mar 11, 2009)

FG wrapped in a plastic bag also works... though in the one pic I don't see *any *insulation on the other side of your plastic-wrapped truck line... just the baffle above, am I missing something?

Gary


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