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Corporate Member
I think it was a video on Matt Risinger's channel. They basically furred out a chamber below the roofs sheating with OSB or something similar for ventilation, sprayed the (closed cell?) foam to the desired R-value to the underside of the OSB and then installed the ceiling finish, capturing the foam as you propose with T&G. I would wonder if something cheaper than OSB could be used to create the chamber as it would not have structural value.


Corporate Member
Want insulation cheap and easy ? Use R-30 or R-38 paper or foil, then use the white fibered Pre-engineered plastic, it looks like Tyvek without writing but, it has embedded a netting sandwiched between the 2 plys of plastic. You probably would only need 1 roll. Staple to the bottom of the joist and then after I would add furring strips on the bottom of joists.
Nice light reflection, light to install and way easier than anything else.......... and low cost


Senior User
Still trying to figure out what to do with the ceiling. I am looking at spray foam and covering it with tongue and grove pieces on furring strips leaving a gap to breath with the joists exposed. Anybody got any ideas. Thanks....
whats wrong with rolled fiberglas?

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