# HOT attic!!



## oh'mike (Sep 18, 2009)

You failed to tell us where you live---that would be some help---

Make sure that the soffits are well vented and that the rafters heading to the soffits are not blocked by insulation.

When you are in the attic without lights on--you should see light coming in around the perimeter at the soffits.

How much roof top vents?


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## Windows on Wash (Aug 30, 2011)

Attic fans are improper in most applications.

Blown in fiberglass is pretty much worthless as an insulator as well.

If your aren't sure if you have enough insulation...you can pretty much guarantee that you don't.


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## bluebird5 (Jan 24, 2011)

every venting system must have an intake and an exhaust. The fan is the exhaust, but do you have any intake vents (soffit vents)? If you don't, the fan will never be effecient because it has no where to bring in cool air from


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## Windows on Wash (Aug 30, 2011)

bluebird5 said:


> every venting system must have an intake and an exhaust. The fan is the exhaust, but do you have any intake vents (soffit vents)? If you don't, the fan will never be effecient because it has no where to bring in cool air from


Yes it does...the house. That is why most attic fans are improperly converting the attic to conditioned space.

You are absolutely correct that exhaust without intake is not correct.

I suspect there is some sort of gable vent or similar.


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## Gary in WA (Mar 11, 2009)

Dooggins1, welcome to the forum!

Again.... where are you located?

Gary


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## Dooggins1 (Oct 16, 2011)

GBR in WA said:


> Dooggins1, welcome to the forum!
> 
> Again.... where are you located?
> 
> Gary


Hey sorry j haven't had time to get here. I live in NC. Yes I do have sofet vents so it is pulling air through. I really just don't now what insulation is best to use if insulation is the answer.


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## Gary in WA (Mar 11, 2009)

Is the HVAC ductwork in the attic? http://www.joelstiburek.com/topten/south.htm

Gary


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## federer (Aug 20, 2010)

GBR in WA said:


> Is the HVAC ductwork in the attic? http://www.joelstiburek.com/topten/south.htm
> 
> Gary


thanks for the link. so unvented attics are better off than vented ones


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## Windows on Wash (Aug 30, 2011)

federer said:


> thanks for the link. so unvented attics are better off than vented ones


Depends totally on construction type and other factors. 

Ventilated attics are a well proven design and when done properly, quite effective. 

You can make a unvented attic just as inefficient as a vented attic if done wrong.


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## AGWhitehouse (Jul 1, 2011)

federer said:


> thanks for the link. so unvented attics are better off than vented ones


In the case of southern buildings, they certainly can be. There are two real reasons why attics are vented. 

1) Moisture control. By exchanging the air within the attic you can control the overall humidity (moisture) levels and promote drying. stagnant moisture within the attic leads to wood decay, reduced insulation effectiveness, and mildew possibilities.

2) Heat control. This isn't so much for the south, but for the north, and isn't so much for summer, but for winter. As in Gary's article, the heat reduction from the ventilation isn't great enough to make a case for definitive use in the south or north during summer. But in the north, the difference of a few degrees in the winter is the difference between having damaging ice dams and having no dams. The ventilation allows for the roof surface to remain cold enough that the snow doesn't melt when exterior temperatures are below freezing.


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## Gary in WA (Mar 11, 2009)

So which type of blown-in insulation do you have and how deep is it?

Gary


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## federer (Aug 20, 2010)

AGWhitehouse said:


> In the case of southern buildings, they certainly can be. There are two real reasons why attics are vented.
> 
> 1) Moisture control. By exchanging the air within the attic you can control the overall humidity (moisture) levels and promote drying. stagnant moisture within the attic leads to wood decay, reduced insulation effectiveness, and mildew possibilities.
> 
> 2) Heat control. This isn't so much for the south, but for the north, and isn't so much for summer, but for winter. As in Gary's article, the heat reduction from the ventilation isn't great enough to make a case for definitive use in the south or north during summer. But in the north, the difference of a few degrees in the winter is the difference between having damaging ice dams and having no dams. The ventilation allows for the roof surface to remain cold enough that the snow doesn't melt when exterior temperatures are below freezing.


thanks. yea that's kind of what i am gathering from all this reading. it's kind of funny but i feel like the more i read the more confused i get. its like theres always an argument against each theory/ design. 

so i guess my concern is-in my case i am doing an unvented roof assembly with open cell foam underneath the decking. the attic is thus part of the conditioned space. so after foam and drywall, i am done right?


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## AGWhitehouse (Jul 1, 2011)

federer said:


> thanks. yea that's kind of what i am gathering from all this reading. it's kind of funny but i feel like the more i read the more confused i get. its like theres always an argument against each theory/ design.
> 
> so i guess my concern is-in my case i am doing an unvented roof assembly with open cell foam underneath the decking. the attic is thus part of the conditioned space. so after foam and drywall, i am done right?


prime and paint the gwb for the class III vapor retarder i believe is required in your area.


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## Dooggins1 (Oct 16, 2011)

GBR in WA said:


> So which type of blown-in insulation do you have and how deep is it?
> 
> Gary


Not sure of the name but it is the white kind. It is about 8-10 inches deep.


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## federer (Aug 20, 2010)

AGWhitehouse said:


> prime and paint the gwb for the class III vapor retarder i believe is required in your area.


what is gwb? should i use glossy paint or is latex sufficient?


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## AGWhitehouse (Jul 1, 2011)

federer said:


> what is gwb? should i use glossy paint or is latex sufficient?


gwb=gypsum wall board, also known as sheetrock.

glossy paint can be latex, oil based, or epoxy. glossy is the finish type, not the paint type.

Yes latex primer and paint are sufficient.


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## federer (Aug 20, 2010)

AGWhitehouse said:


> gwb=gypsum wall board, also known as sheetrock.
> 
> glossy paint can be latex, oil based, or epoxy. glossy is the finish type, not the paint type.
> 
> Yes latex primer and paint are sufficient.


thanks for clarifying. yea what i meant was would glossy finish be better because aren't one supposed to use that in a bathroom where there is much more humidity vs basic latex finish.


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## AGWhitehouse (Jul 1, 2011)

federer said:


> thanks for clarifying. yea what i meant was would glossy finish be better because aren't one supposed to use that in a bathroom where there is much more humidity vs basic latex finish.


Not necessarilly. "basic" paint finish is called "eggshell". Glossy finishes aren't significantly any more resilient to moisture than other finishes. The difference is really in the maintenance. Glossy surfaces don't grab dirt as easy and are therefore easier to clean.

*Paint finishes:* *http://www.wisegeek.com/what-are-the-different-types-of-interior-paint-finishes.htm*


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## Gary in WA (Mar 11, 2009)

OP, sorry for the thread hi-jacking. Your location in NC makes a difference for the minimum insulation required per code, 3 different zones, find yours: http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_11_sec001_par001.htm
Then find the ceiling requirement: http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_11_sec002.htm

Gary


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