Rafter baffles11/20/2022 ![]() Just a side note for what's coming in the 2015 IBC: Nonventilated attics and rafter spaces are permitted (conforming to the same requirements that have been in the IRC). The IBC requires vapor retarders in Climate Zones 6, 7, and 8, so those zones will need to have a vapor retarder worked into the roof assembly. Gypsum board applied directly to the bottom edge of the rafters forms the air barrier. The IBC requires a 1-inch gap between the insulation and the roof deck connecting eave and ridge vents. The gypsum board at the ceiling provides the air barrier.Įnclosed Rafter Spaces: The space between the bottom edge of a rafter that forms the ceiling and the top edge of the rafter for the roof deck. #Rafter baffles freeThe free flow of air through the attic is permitted/required. Insulation is above the ceiling at the ceiling beams (usually the bottom chord of trusses). There are two things that need to be ventilated per the IBC: attics and enclosed rafter spaces.Īttics: Defined as the space between the ceiling beams of the top story and the rafters. Seems less expensive than trying to seal a rafter vent space. Penetrations for light fixtures and vents will need to be properly sealed. Geren, FCSI, AIA, CCS, CCCA, SCIPĭon't forget that gypsum board, when properly taped and finished, is an acceptable air barrier (not a vapor retarder). It may well be that it is too late for that decision, or unlikely to be accepted because it is so unconventional, but if one wants an air barrier at the roof in wood frame construction, it may be the only practical way to do that. I have pushed for a composite roof deck product (plywood factory laminated to insulation with spacers for venting), but everyone thinks this is too expensive.Īs you may know, Joe Lstiburek has long advocated eliminating the vented attic, in favor of a sealed conditioned attic space, which would allow an air barrier somewhere in the roof assembly. #Rafter baffles installThe idea is that the insulation contractor (who will probably install this stuff) will seal the edges of this product against the rafters (I didn't say this was a good idea). There is really no way that you are going to put an air barrier in the attic roof assembly. The problem with venting the attic is continuity of the air barrier. That is what soffit vents and ridge vents are for. Even vaulted ceilings have a air space between the insulation and the plywood. I believe that most attic spaces are designed to be vented and should not be sealed. What are the chances of a typical residential insulation installer (or whoever installs this) achieving a virtually flawless, leak-free condition (since that's what an air barrier requires)? How would a vent baffle be "properly sealed"? Sealant or tape on each baffle, each side of each rafter?Ģ. This is a 3-story, wood framed, residential facility (similar to a fraternity or sorority) with an asphalt shingle installed over underlayment and plywood roof deck.ġ. Does anyone have any experience with this or have any other products we should consider? My client believes that when properly sealed, they will also serve as an air barrier. Durovent is a product I found my client (the Architect) found a product called SmartBaffles. Plastic "spacer" installed under the roof deck in wood construction to provide a vent space between the underside of the plywood deck and the insulation. 4specs Discussion Forum: Attic Vent Baffles ![]()
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