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nibs · 08-21-15, 08:00 PM

Am building a flat roof will be about 20 X 35 when done, this year 20 X 20.
Have a source of free styrofoam insulation chunks, every thing from sheets of 4" missing chunks, to curved bits and thin strips.
I saw the odd shaped pieces into cubes and pack them tight into the spaces between the box beam trusses. Am very careful to get tight fits, & use canned foam and backer rod as required, the last 1/2" or so will be epscrete under the plywood so that there are no air gaps to allow condensation to form.
The styrofoam is minimum 8" deep and max 11" deep because of the run off slope. The box beam trusses are 2X4 with 1/2" plywood glued and screwed to the 2x4 frame. the trusses are filled with rock wool batting..
Will probably lay the first row of plywood Sunday or Monday
Any one see problems with using the styrofoam pieces?

08-21-15, 08:00 PM	#1
nibs Apprentice EcoRenovator Join Date: Jun 2010 Posts: 206 Thanks: 1 Thanked 18 Times in 17 Posts	Styrofoam Insulation. Am building a flat roof will be about 20 X 35 when done, this year 20 X 20. Have a source of free styrofoam insulation chunks, every thing from sheets of 4" missing chunks, to curved bits and thin strips. I saw the odd shaped pieces into cubes and pack them tight into the spaces between the box beam trusses. Am very careful to get tight fits, & use canned foam and backer rod as required, the last 1/2" or so will be epscrete under the plywood so that there are no air gaps to allow condensation to form. The styrofoam is minimum 8" deep and max 11" deep because of the run off slope. The box beam trusses are 2X4 with 1/2" plywood glued and screwed to the 2x4 frame. the trusses are filled with rock wool batting.. Will probably lay the first row of plywood Sunday or Monday Any one see problems with using the styrofoam pieces?