Efficient attic ventilation

[Daox]

So, I've been looking for a house since around winter. Last weekend we finally looked at a propery that has almost everything we want. I'm not very knowledgable about house building and efficiency, so I've been reading up on it as much as possible the past few months. However, I did notice when I went into the attic of this house (2 story old farm house) that it was HOT. I'd say it was well over 100 and that was on a 70 degree day. The house doesn't have A/C, but they fairly recently put a new roof on the house. I would have assumed they would have put in adequate venting. Ok, I did help do two roof last year so I at least know a little. In any case, what can be done about this? I assume vents are normally put in before shingles etc and ripping things up wouldn't be very fun. Is there an easy fix? Any links to good sites would be great too.

[PaleMelanesian]

At a minumum, put a couple of those turbine vents up there, WITH (very important) some soffit vents under the eaves. Air leaving the top doesn't help much if there's no air to come in and replace it. It also promotes natural convection cooling - hot air rises and goes out, and cool air comes in at the bottom.

Next step would be a ridgeline vent. Since it lays over the top of the other shingles, it should be a good retrofit option. You'll have to cut a slot along the ridge for air to come out, probably with a circular saw.

Then I would consider a solar-powered fan.

Any of these would be doable with the existing roof in place, though you might need a couple replacement shingles right at the work area.


How's the insulation on the attic floor? You felt the heat - it wants to come in through the ceiling.

[SuperTrooper]

When I replaced the roof on my previous house, a ranch, I had a ridgeline vent put in. I already had soffit vents and gable vents but the ridgeline made a huge difference. They can be installed after the fact. Turbines work, but they do take some upkeep and they're harder to install afterward. And the fewer holes in the roof you are trying to seal the better. Make sure you have PLENTY of insulation above the ceilings. Keeping the heat in the house in the winter prevents ice dams on the eaves.

[elhigh]

Do one or the other, not all. If there's plenty of space up there then you don't need to add the ridge vent - that's best for when the space under the roof is occupied. If the entire attic is open, you can add just the turbine or the powered gable fan and have done.

Regardless, you will still need to add soffit vents.

[jamesqf]

Originally Posted by SuperTrooper

Make sure you have PLENTY of insulation above the ceilings. Keeping the heat in the house in the winter prevents ice dams on the eaves.

And keeps money in your wallet, summer and winter. I'd say that adequate, or even over-adequate, attic insulation is the single best thing you can do. When I bought this place, I started by putting in a powered attic fan, which didn't help that much in the summer. Second year I added a second layer of ~R30 insulation to what was there, and haven't used the fan since.

PS: I don't use A/C either, though I'm in Northern Nevada, so probably a lot hotter than you.

[Arminius]

The solar-powered vents are fantastic. They are easy to install and they don't attract attention. You can also turn them off in the winter.

[Daox]

I looked at the house once again over the last weekend. When the roof was redone it appears that they put in a ridgeline vent (thats what I wanted to see). However, there are no soffit vents. So, it looks like I'll get to put some of those in. Its a small 600 sq/ft attic with gable ends, so I think that should be enough. I'd rather not have to go for an electrically powered option.

[fshagan]

Are you in a hot area that has a respectable drop in temperature when the sun goes down? If you are, and like to run fans in the house to cool it, another option is to install a "whole house fan" ... I had one in Riverside CA and loved it. It is a huge fan that pulls into the house from outside and blows it into the attic ... and pushes it out the vents. It made a huge difference in our A/C bill.

[Daox]

Hot summers really aren't a big problem. I'm in Wisconsin. I actually just put in my window AC units last night. Other than that I can get away just opening up the house at night and puting a fan in the window to pull air through the house. I'm much more worried about keeping the heat in during winter.