# Attic Insulation Baffle Vent



## Crazyjake8493 (Sep 26, 2014)

If money permits, my ideal way to install baffles is to screw 2x2's to the rafters against the roof decking, and then cut strips of foil-faced polyiso insulation to fit between the rafters, screwing them to the 2x2 cleats.

I usually just use the foam baffles and have not had a problem with them coming loose. You only need to use them where you need to keep insulation from contacting the underside of the roof, not in the entire unfinished attic space. The insulation against the baffles should help the staples holding them in place.


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## jklingel (Dec 21, 2008)

As jake did, but use 3/8 ply instead of foam if you are worried about tear-out.


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## Bud9051 (Nov 11, 2015)

CTS, I agree with your concerns. Wind and time will definitely cause the staples to fail. But, the insulation should hold them in place. But, this should be a long term installation and 20 years shouldn't be out of the time frame. 

But here's my concern. Building a plywood baffle is actually no different than installing the insulation directly against the bottom of the roof, it becomes the cold condensing surface. Using enough rigid foam isolates the cold from the warm side where there is a potential for moisture. The flimsy baffles that do not cover the entire bottom of the roof avoid some of the risk by allowing some of the cold air to access the insulation. 

No citations and other thoughts welcome.

Bud


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## jklingel (Dec 21, 2008)

ok. here is a citation and other thought, if you wish. should the plywood get wet, and it may, it will also dry fairly easily. there are people here that build with tall energy-heel trusses and run the sheathing right up the side of the house, over the end of the truss, and up to within 2-3" of the roofing; no issues. the problem with the insulation against the roofing is that the plywood there can not dry. if the house is air tight, there should not be any moisture sneaking out to speak of anyway.


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## AlphaPilot (Aug 6, 2012)

Interesting opinions. Glad I'm not alone on the concern. Yes, if I have insulation touching these baffles, it will help support them. However, I have raised heel energy trusses. So, My insulation doesn't really touch much of the baffle (Hence, the rattle / wind noise). If I were to get ambitious, I would be getting in the attic and blowing in a good 6 or 8 inches of Cellulose, making the baffles more rigid. I may not do this, especially if I go and build another home! Regardless, I want to know and practice a better material for baffles. I like the foil faced foam idea. Poly-Iso, foil faced is not the cheapest stuff out there, but it's probably durable. The thing with poly iso is it can absorb moisture and hold it. That's no beuno. And I am not sure if say 1" thick poly iso, with cut edges, would be a long lasting baffle material. Especially those screws. A nice amount of construction adhesive would probably work, but screws would wiggle loose as air blasts past over time I imagine. Will do some more research. Maybe a wood/foam hybrid. Something to prevent moisture from collecting.


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## AlphaPilot (Aug 6, 2012)

I dont think the plywood or OSB is a bad idea. There should not be much condensation at this point because, well, it's the attic...an unconditioned space. It's super cold in the winter and contact with wood isn't a problem as long as that wood is not warm, or as long as the insulation is not warm and the wood is cold. Now, I could see an issue maybe if there are air leaks at the top plate of the exterior wall near the baffle, and warm moist air can get to the freezing cold wood.


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## jklingel (Dec 21, 2008)

"... if there are air leaks at the top plate of the exterior wall near the baffle, and warm moist air can get to the freezing cold wood." roger that. i am sure that the wet air will condense on anything, including the insulation. bottom line: air seal well.


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