2020 Boise Idaho Real Estate Blog
summer attic temperatures warrant Ventilation Main The Durable Green Home
We get lots of comments on whether or not to add ventilation in attics in the summer to reduce the attic temperatures, makes sense right?

Yes, increased ventilation in attics is a great to reduce the build up of attic temperatures in your attic, which in turn will reduce the cooling load of the house, but there is more  that you need to know. First off I am a fan of passive ventilation strategies first. So enlarging gable vents can work very well, switching to ridge vent ( external baffle like Certianteed air vent ) is great also, or in some  cases mechanical ventilation is  the only means. let me say this, you will never have enough ventilating with the Jack vents ( small plastic or  metal vents on most homes ) Code  is not  even being met on most all homes. code says ( not installed) 1 sqft of net free area per 300 sqft of attic, most  roofing manufactures say it should be closer to 1/150 ( twice what code says) so on a 2000 sqft home with a 7/12 pitch roof you would need 29- 40" net free area vents. Go  out and count  your  vents or  your neighbors. my guess  is you have about 8-12, which in this case would  not even meet code. the other kicker is you need more net free area at the soffits as at the ridge so the vents draw correctly, and you never combine ridge ventilation or gable ventilation strategies ( which in alot of cases has been done ) So really the only ventilation that works is ridge, gable, Copulas, or  mechanical. BUT BEFORE YOU ADD VENTILATION- you should blower door test your home and air seal the attic and penetrations. if you just  add ventilation you can draw more conditioned air out of the home through HOLES and increase your cooling and heating load ( higher  costs of utilities ) done correctly with air  sealing first ( non air tight cans are the worst things you can do in a home ) and good  ventilation attic temperatures can be decreased significantly - like  up to 30 degrees!! or  more!! Radiant barrier paints  have also been used to some degree  of success, but  ventilation should be your first  priority. Don't  think just because you hire a remodeling contractor or building contractor they understand proper ventilation. get some advice from ventilation experts, websites www.airvent.com, www.eeba.org , or have an energy audit done on your home with a blower  door www.onpointadvantage.com Also if you have a furnace in the attic there are other safety tests that should be done to make sure your ventilation does not cause other problems with to much negative pressure in the attic.  Also air sealing before  you re-insulate should always be done first so  you get the results you paid for.

Posted by Tad Duby at 6/12/2008 1:42:00 PM
Comments (2)
Re:summer attic temperatures warrant Ventilation
Perfect timing. I have a question. My attic has itty bityy pvc pipe that ventlates the attic and I have a fan over the garage. I don't think the fan ventialtes the oth end of the house because there is too little vents to pull from. I was thinking that instead of pulling I would reverse the fan and push air into the attic. Any thoughts even though you have not seen my house which I am not going to show you because it would b the poster child for pitiful efficiency.
Posted by on 6/12/2008 6:26 AM
Re:summer attic temperatures warrant Ventilation
Hey Tad- I always love your Blogs. You've heard of computer geeks ? Im a high performance building geek. Just like computer geeks like to tweak, and tune computers to make them RUN FASTER, RUN COOLER, MORE EFFICIENT, MORE RAM, MORE MEMORY, blah, blah, blah you know the drill. Well, Im that way with my houses.
I have learned some new tricks, and want to share them as they pertain to this topic.
By the way, you are right most homes don't even come close to having enough attic ventilation. Fact is, even if they do have enough vents "according to code" they still dont always have enough ventilation. Your home may even have twice as much ventilation as code requires, and not always have enough ventilation. For the readers to understand my point all they would need to do is make a trip up into there attic this Sunday afternoon about 5:00 pm and just hang out up there for a little while. We are supposedly going to be in the 80's this weekend ( lets hope summer is actually coming). Assuming we make it to 80 this weekend your attic should be nice and hot. Probably well over 100 degrees with or without proper ventilation. I wont even suggest you try this when summer really gets here and our temps eclipse the century mark, and they certainly will.

So Bond- What than is the solution?

1. Remove the roof from your house.
Just kidding- that wont work, we definitely need roofs on our houses.

2. Eliminate the attic by conditioning the space.
Whoa- what did he say? Come on whats he even talking about? "Condition the space" thats not how my Great Grandfather did it, he must be crazy.

If you would like to get more information on how to turn your attic into conditioned space, solve all of these ventilation issues, make your home more energy efficient, add usable storage space within your current building envelope, increase your indoor air quality, and make your home greener.
Visit my website www.leedidaho.com go to the Blog tab and read more info on conditioned attics. If you would like to see a conditioned attic in person send me an email at [email protected]

For the other high performance building geeks like me, who take me up on the challenge of going into their attics this weekend: After your cold shower, and a colder beer, send me an email, then come on over to see the difference a conditioned attic makes.

Bond Campbell

Posted by on 6/12/2008 1:55 PM
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Michelle Penick, Build Idaho Client Real Estate Services

Michelle Penick

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