Plywood Baffles + Wind Dams
A contractor helping on my PGH renovation (at least I think it’s going that direction 🙂 ) made a mockup of a site-built baffle made from plywood today. It’s a deeper channel than the 2″ advised in previous GBH article, though we could adjust to 2″ if advised. We’re working off this previous GBH article (Thanks Martin):
I think it’s best to use foam insulation for the wind dams, as it will also insulate a bit against coming up through vents and into house. There is some leftover 1.5″ or 2″ rigid foam of some kind from previous owner, so I’d like to recycle and use this for the wind dams. We would cut the top at an angle matching angle of baffle coming down, then use caulk or perhaps spray foam to air seal.
Fyi it’s a gut renovation, so we have things down to studs now. The soffits were just redone, with continuous soffit vents along all exposed parts of truss that lead up to the ridge vents.
Latest building envelope diagram is also attached for reference as PDF. Two images of the new soffits and vents are in the PDF.
* Foam for wind dams good idea? Is thickness of the rigid foam enough to insulate from cold seeping in? Or better to double up and get more R value here? If more R value, we’d need to move baffle up a bit in order to fit more foam on top of sill for the wind dam.
* We will air seal on left, right and top of the wind dam. Should we also seal along seams of the baffle up to top? This first test is pretty tight to each side of truss, but if advised, we can air seal here too.
* Insulation will be blow in cellulose to 18″ for R60 (will settle to 16″ according to insulator). To be safe, should we get baffle to 20″ above point where cellulose will start piling up? (bottom of horizontal wood in truss). At the moment, the first demo is at 12″ and clearly we need to go higher. Contractor is trying to be efficient with the ply and cuts.
* Should we stick with 2″ vent space for baffle mentioned in article, or is a deeper version ok too?
* Have not done materials + labor comparison between plywood site built and buying the Accuvent or whatever that 1.75″ advised plastic baffle is. I like the vapor permeability of plywood though, because house had previous mold / moisture problem. Ideally this reno fixes the issue with the plans but maybe best to stick with ply?
Any input is welcome. We should be fine, but it’s a first time building these and would appreciate feedback from more experienced hands…
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