Last year I converted from baseboard heat to a gas-forced air furnace in order to get central air and humidification in my house. The only place to put it was in the attic. Even though the ducts are wrapped with insulation, enough heat is given off to melt the snow on my roof and ice is damming up in my eavestroughs.
I currently have soffit vents, gable vents and a ridge vent in my 1500 square foot attic. I have thought of insulating the roof, with either foamboard over the inner side of the roof trusses (so that the soffit vents would still connect with the ridge vent) or with the stapled foam channels that you can put fiberglass insulation over, then sealing up the gable vents. I’ve priced both options, and it seems to be a wash cost-wise.
This would give me a conditioned attic, which would hopefully increase the efficiency of my heating and cooling and stop the snow from melting on my roof. I have a whole-house fan that my wife and I love in the spring, so I would consider making the covers for the gable vents removeable.
Has anyone done this before, or have any advice/suggestions?
Replies
I wonder if it would help if you just covered the gable vents. That would allow the soffit and ridge vents to do their job, and the cold air would flow up the underside of the roof sheating, as it's supposed to.
Depending on how much ridge and soffit vent you have, you may not need to uncover the gable vents. The attic fan might be able to force air out the ridge/soffit vents if there's enough net free area.
Actual size *doesn't* matter. It's how big you can convince her it is that matters.
You might want to look at http://www.buildingscience.com
I know that they STRONGly recommend doing this for hot climates with the AC in the attic.
Don't know about the cold climates, but some of the reasons would be the similar.
Thanks for the link, Bill. This website looks very interesting.
I think it wise to bring the HVAC inside the building's envelope.
I'd use RFBI, polyisocyanate, nailed with buttons to the faces of the rafters.
Details? Where do you live? Try a search (oouuch!<g>) for any of the attic conversion threads, the techniques are, for the most part, the same.