Attic space very hot...

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Old 08-04-19, 10:25 AM
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Attic space very hot...

Just put on an addition and finishing up insulating my unoccupied attic, I have vents in all my rafters and a ridge vent running across my roof. I've noticed in hot weather when there is no breeze my attic seems very hot, on a hot windy day it seems to be cooler. Should I put in a power vent or a side gable vent to help the heat escape on these non breezy days? I've never been in a non occupied attic before so I'm not sure exactly how hot they're suppose to get.
 
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Old 08-04-19, 01:35 PM
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Its an attic and attics get hot, windy conditions help but that just proves that your ventilation is working, does not mean you have any issues!
 
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Old 08-05-19, 08:20 AM
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Attic ventilation was never meant to cool our attics in summer. The air flow removes winter heat to prevent snow melt and resulting ice dams. it also remove any moisture that escapes from the house.

Protection from the summer heat comes from an A+ air sealing job between house and attic and at least code recommended minimum insulation. 2' of insulation does wonders for keeping the heat out.

You mention "I have vents in all my rafters " are those the baffles that provide air flow below the roof or are they the actual vents in the soffits. The actual vents need to have plenty of net free area.

Bud
 
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Old 08-07-19, 05:34 PM
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My attic is very well insulated, I have 2 layers of R-30 in my ceiling joist and the vents I mentioned are baffles, there is no insulation in my roof rafters. I was just curious if I needed a gable vent or a power vent to cool the attic space down a little. Wasn't sure if it got to hot up there if it would dry out my trusses and plywood. I was just a little concerned after seeing sap running down my trusses.
 
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Old 08-08-19, 07:39 AM
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Passive venting like adding gable vents or roof vents will not make a huge difference in attic temperatures. A powered vent can but at the risk of pulling conditioned inside air into the attic through the many air leaks. Unfortunately sealing all of those leaks after the house was built is difficult and made more so when buried under lots of insulation. The fiberglass insulation does not reduce that leakage as air passes right through it.

As for the heat and your trusses I suspect that will not be an issue.

Are you having any cooling issues at present?

Bud
 
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Old 08-08-19, 08:08 AM
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Your attic sounds perfectly normal, and as long as you have proper vents, it's fine. The roof vents are important for the purpose of controlling humidity, but will have little to no effect on temperature. As far as a fan, yes, it will cool your body, through evaporation, but it is going to provide next to nothing as far as cooling the space. If you go into your attic first thing in the morning following a cool night, you will find it much more comfortable, but by say 10:00 or so, when the sun is beating down on the roof, it is going to start climbing, and no amount of air movement is going to actually cool the space because any air that is drawn in is the same temperature as what is being kicked out. It's just compounded up there because the rafters, joists, and eheathing are all heat sinks.
 
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Old 08-08-19, 05:00 PM
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Thanks for all the information, I'd rather ask questions and be safe than sorry.. thanks again.
 
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