# Excessive HEAT in Attic



## diyaz (May 23, 2013)

Every summer - here we go...my attic heats up almost twice to whats outside on a hot day. I have two separate units, and the upstairs unit runs all day to keep up with its target set point. 

Disclaimer: I am an average consumer with no technical skills or knowledge about how things work in construction. 

My possible solution(s) as recommended by few local vendors I have consulted -
1) Make cuts on the roof top (dont know the term for that - but the part where the roof eventually meet on top to make a triangle shape). Basically let hot air out of that part since hot air supposedly only travels UP. This is per vendor #1.
2) Put what they call 'radiant shield' that lines the roof from underneath to prevent heat or cold from penetrating thru the shingles and wood. Vendor #2.
3) Insulate the entire roof that would bring the attic temperature close to room temperature. A more expensive option by same vendor #2. 

My preference is to just install 2-3 Solar Fans that will pull air out. The one at Costo has a remote control that I can set and all that. 

I would like an expert opinion on what is the most cost effective way to fix this issue. Thank you.


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## paintdrying (Jul 13, 2012)

we need your location, and some pictures. This is a hotly debated topic. Ha Ha hotly, get it...


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## gregzoll (Dec 25, 2006)

What are you stating is "excess heat"? All attics will get warm during the Summer months, warmer if there are no trees over them. Even with passive cooling, they can stay around 115-125. With active cooling, you can see temps low around 110-115, or even 90-110 with tall enough trees, to shade the structure, along with powered venting.


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## diyaz (May 23, 2013)

It goes above 150. Even in spring when it's nice outside its intolerable. The vendors who came in were soaking in the attic. 

This is Western Kentucky. 

Thanks for your concerns.


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## roofingquotes (Mar 6, 2013)

Our attic at home also gets hotter even with proper ventilation. I think its normal for attics to get hotter every summer.


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## paintdrying (Jul 13, 2012)

Do you have soffit vents? Do you have a ridge vent/? Power vents may or may not be the answer. Without some pictures, you are just blowing hot air.


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## Nailbags (Feb 1, 2012)

what type of ventelation do you have right now? Ridge vent? gable vents? soffit vent with either ridge vent or gable vent? Lets start there and work up.


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## diyaz (May 23, 2013)

Soffit vents. I am not too sharp on technical terms but its the one that is located at the bottom of the roof, where it meets the floor. That's it. Don't have any openings on top. I am going to post pics later once I figure out a way to do it. Sorry if am being so ignorant but I appreciate the reassurance so far.


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## gregzoll (Dec 25, 2006)

diyaz said:


> It goes above 150. Even in spring when it's nice outside its intolerable. The vendors who came in were soaking in the attic.
> 
> This is Western Kentucky.
> 
> Thanks for your concerns.


You need to figure out best ventilation before thinking about adding power vents. Pictures of the front, back, sides of the structure helps to show us what you are dealing with, along with a shot of the inside of the attic.

I do not have soffit's, so we had to go with vents along the ridge, and then they still did not help get the space down below 130, so added a power ventilator. It kicks on around 95 degrees. On a hot day around 98 with 70-86% humidity outside, our remote sensor up there, shows it around 110 when I get home around five at night, and will usually shut down around 7:30 to 8 on those hot days. It kicks on usually around 1-2 in the afternoon.

Normally if it is say 86 outside, the attic fan will shut down usually by 5:30-6 in the eve, and is around 92 when I get home at 5. Adding the remote sensor up there, allows me to watch the temps, so that I can better control the a/c. I use a Radioshack Weather Forecaster, that allows three remote sensors, but cur. only use two (basement, attic). Main unit sits on the end table where I sit, when I get home after work.

We just do not have the space at the bottom edge to add soffit's, so we have to "bandaid" the airflow fix. I still have to get up there and add baffles, which you may also want to look into, if you do not have them, so at least you can get whatever air to come up along the bottom edge up towards the ridge, to also help with cooling.


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## RWolff (Jan 27, 2013)

My attic fan has a 100 degree thermostat on it, and it's come on during a semi cloudy day when the outside temperature is in the 60s even, attics get hot.
You do need plenty of soffit vents. My house is a cross-gable, so it has 3 gables, one of them has the power fan, the other two have decent sized screen louvers to admit cooler air. I also added a continuous ridge vent.
I noticed a definite difference because my house never had soffit, or ridge vents, all it had was 3 screened louvers, but now with soffit vents I added, the ridge vent and the power fan I noticed the A/C if more efficient, and the attic heat "soak down" from the ceiling after sunset when the heat during the day penetrates the insulation is no longer there.


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## gregzoll (Dec 25, 2006)

RWolff, add in the low humidity levels of attics, they make perfect preservation for mummies.


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## jeffnc (Apr 1, 2011)

Soffit vents alone don't do any good. You need to add gable vents or a ridge vent. I'm not sure how you got a house with only soffit vents. Did you have your roof replaced, and the took away the ridge vent for some reason? You can add a ridge vent without replacing your whole roof.

Of course foam insulation on the inside of your roof, or reflective barriers, will work. But basic venting and airflow comes first.


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## mikegp (Jul 17, 2011)

If you insulate the underside of the roof it could reduce the lifespan of your shingles/roof material.


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## RWolff (Jan 27, 2013)

gregzoll said:


> RWolff, add in the low humidity levels of attics, they make perfect preservation for mummies.


Perfect for preserving departed Mummies, and MOMMIES too depending on the particular homeowner and their circumstances :jester:


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## jeffnc (Apr 1, 2011)

mikegp said:


> If you insulate the underside of the roof it could reduce the lifespan of your shingles/roof material.


Correct (and usually you will void the shingle warranty). In the case of foam, you would have to install baffles first.


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## Gary in WA (Mar 11, 2009)

You are in Zone 4; http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_11_par002.htm

Code requires R-30 ceiling: http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_11_sec002.htm

Do you have a full attic or knee-wall and top attic with cathedral (sloped) ceilings;pp. 10, 11; http://www.awc.org/pdf/WCD1-300.pdf

Attic air sealing; first, insulation; second, ventilation; third.
How to post a picture, first group on the list; http://www.diychatroom.com/f98/
or describe the attic/rafters better.


Gary


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## paintdrying (Jul 13, 2012)

What are these baffles before foam insulation underside of roof. Where do you look for air leaks?


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## gregzoll (Dec 25, 2006)

mj12 said:


> What are these baffles before foam insulation underside of roof. Where do you look for air leaks?


For air leaks, anywhere that you have a access hatch, whole house fan, wires entering the attic through the walls, pipes, chimney's, etc.. As for the baffles, they are foam, and placed at the edge, where roof meets ceiling of the living space, so that even if you do not have soffit's in your home, it allows air to come up through into the attic, for better ventilation.


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## jeffnc (Apr 1, 2011)

Baffles normally allow a channel of air kept open down to the soffit vents, so they don't get covered by insulation. But when the underside of your roof is coated with foam, they serve another purpose - to keep a cushion of air to buffer the shingles from overheating. If the sun beats on your shingles and the heat is trapped, it can cause premature wearing of your shingles.


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## Nailbags (Feb 1, 2012)

were I live foam sprayed on the sheathing of a roof in the attic is a major code violation. Not alowwed to do it will cause very premature roof failur at best.


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## Gary in WA (Mar 11, 2009)

Where are you located, Nailbags?


mj12, are these rafters with drywall attached* or* open attic; insulation on ceiling joists/floor?

Gary


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## jeffnc (Apr 1, 2011)

Nailbags said:


> were I live foam sprayed on the sheathing of a roof in the attic is a major code violation. Not alowwed to do it will cause very premature roof failur at best.


Very premature roof failure at best. Hmmm. I shudder to think what might happen at worst. Immediate explosion of the premises?

And you live in Pacific Northwest, where it isn't hot.

Sounds rather exaggerated to me. It shouldn't be a code violation at all if baffles are in place. And if they're not - then code violation or no, there's certainly nothing worse going to happen where you live than in more difficult climates.


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## SPS-1 (Oct 21, 2008)

jeffnc said:


> Soffit vents alone don't do any good.


 
Exactly. Ambient air enters the soffit vent, and exits at the top of the roof. With only an air inlet and no air exit, you don't have any ventilation for your attic. Sounds like you already have one quote for adding roof vents. Call at least one other roofer, and just say "I am not sure if I have sufficient attic ventilation". You may find different roofers have somewhat different opinions on how best to ventilate the attic (i.e ridge vent, whirly-birds, etc). I am figuring the salesman should be asking to go up into your attic to check that the soffit vents are not plugged (its too common that people insulate their attics and stuff insulation over top of the soffit vents).


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## gregzoll (Dec 25, 2006)

Nailbags said:


> were I live foam sprayed on the sheathing of a roof in the attic is a major code violation. Not alowwed to do it will cause very premature roof failur at best.


Correct, should be applied to the ceiling area of the living space, if the attic is not going to be used as living or finished space for storage. Otherwise, you apply per directions at http://www.icynene.com/

Remember, it is the heat from underneath that causes breakdown, along with if you do not have shade above, beating sun will cause breakdown. We also discussed the subject of Spray foam for attics, back in 2008 http://www.diychatroom.com/f19/air-cavity-required-behind-spray-foam-roof-insulation-21915/


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## Gary in WA (Mar 11, 2009)

Insulating the attic from conditioned space will work the best; R-38 is required per code for your Zone4;http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_11_sec002.htm

This will stop/slow 98% of the heat flux; http://www.google.com/url?sa=t&rct=...VjgAkW8XzKgQkGg&bvm=bv.44442042,d.cGE&cad=rja

Radiant/with venting stops/slows 28%; http://www.rfoil.com/pdf/8-Effect-of-attic-ventilation-on-performance.pdf

I would air-seal the attic first, add code minimum insulation R-value; http://www.google.com/url?sa=t&sour...sg=AFQjCNHwd56o0AxLi8-V03E5cMUmwWATQw&cad=rja

http://www.finehomebuilding.com/PDF/Free/021105092.pdf

Ventilate the attic better if showing signs of excessive heat/moisture in attic framing/on shingles. http://www.professionalroofing.net/archives/past/mar02/feature2.asp

At least to code (minimum); http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_8_sec006.htm

Use a fan only if the air path from soffit/ridge is restricted (hips/valleys/dormers/etc.) http://www.greenbuildingadvisor.com...nce/are-solar-powered-attic-ventilators-green

Is any HVAC duct/unit in attic? 

Gary


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## Dave Sal (Dec 20, 2012)

I had a similar problem a long time ago. The upper attic (tri-level home) would get extremely hot during the summer. I added extra insulation which helped quite a bit but I needed to do more. Extra soffit vents helped again, but since my roof shingles are brown the sun really heats them up. I decided to install a power attic vent and have been monitoring the attic temps with a remote thermometer sensor. On hot, sunny days it used to get above 125 routinely. Now with the addition of the power attic vent it stays around 105-107 at the highest. The only issue I had was when a raccoon decided to climb into the attic through the power attic vent. It tore off the screening around the edge and then bent one of the fan blades and jumped down into the attic. In the first pic you can see one of the fan blades bent down. I could hear it walking around up there one night so I went to my local police department animal control office and borrowed a trap. Baited it and stuck it up there but never caught it. I was lucky in that I placed it directly underneath the attic fan and it used the trap as a sort of ladder and apparently climbed out on it's own. After that I bought some heavy gauge mesh and secured it to the underside of the fan opening. Nothing is getting through that. (knocks wood).


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## Windows on Wash (Aug 30, 2011)

If you are not going to treat the attic as conditioned space, there is zero reason to insulated the roof deck.

Get the venting figured out and if you have soffits (albeit unclogged or obstructed) vents, a proper soffit-ridge combination will work perfectly when done right.


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## paintdrying (Jul 13, 2012)

I have seen guys take 2 inch foam board and attach it flush with the bottom of the attic rafters. They leave an 1/4 inch gap on each side and then spray foam everything together. I guess that is the same as installing baffles and spray foaming the ceiling. Would you also use baffles on a south facing wall if it was going to get spray foamed as well?


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