How to insulate an attic
HuubD
| Posted in Energy Efficiency and Durability on
Hi,
I am looking for insulation advice on our new build in south Texas. It is a one story 3,000 sqft home. The goal is to minimize spray foam and use either rockwool or Pink next gen in the walls. What are my options for the roofline insulation. I try to avoid blown in ceiling insulation and much rather have a conditioned attic. The build is in a phase that I can still make changes if needed.
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Replies
HuubD,
Check your local code. You should be able to use batts against the roof sheathing, with a vapor-diffusion port at the peak.
https://buildingscience.com/documents/guides-and-manuals/gm-2101-guide-building-conditioned-unvented-attics-and-unconditioned
Hi,
Thanks for your response. Your suggestion is definitely one option I am considering. Currently ridge vents are installed. The other option I am considering for the roofline insulation is either open or closed spf and sealing off the ridge vents.
I would put in vent baffles, then batts. Fur out the rafters to accomodate enough batts to reach the R value target you have in mind. If you can, put the furring perpindicular to the rafters, so that you can use two layers (or more) of batts oriented 90 degrees to each other, which will greatly cut down on thermal bridging.
Note that you need soffit vents in addition to the ridge vent, since the venting components (ridge vent, soffit vent, and vent channels) work together as a system.
You'll need an interior side air barrier, but it doesn't have to be anything fancy. Taped polyiso, drywall, even plywood will work, as long as you meet any local codes for fire resistance.
Bill