I am turning my 2-car attached garage (18.5’x24′ with a low hip roof – only rises 3′ at the center line) into a woodworking shop. It has a new insulated hurricane proof 16′ garage door (we live on the water in Florida’s west coast). Only one small window and a new entrance door to the exterior. The attached wall faces east, the garage door faces west. The small window and entrance door are on the north side. Part of the south wall is common with the main house. I just installed a new mini-split 1-ton air conditioner & heating system (works great even with NO insulation and open soffits). The garage has open soffits on three sides; there is no ridge or roof vents. I just put a new concrete tile roofing system on the entire house and garage (and I am unwilling to install any ridge vents now that the roof is new – at the time of the new roof I did not know that I was going to turn the garage into a shop). The roof rafters are 2×6 on 16″ centers.
I am seeking suggestions for how best to insulate the garage roof. I have had an estimate to install 5″ of icylene foam at a cost of $1,595. I’m told that I would then need to cover the foam with a 15-minute thermal barrier – whatever that is!
Thanks for your help.
Jeff
Treasure Island FL
Replies
Well I would go for the icynene. So you are looking at about 600-700 sq ft of roof to insulate? Yeah they want you to cover it with drywall before you use the space. That is your 15 minute barrier. Safety reasons I suppose.
I paid $2084 to cover 1560 sq feet of area with icynene. This was with 2x4 construction. Walls mainly and some crawlspace and the dimensional 2x4 roof rafters. Converted garage apartment at 20 ft by 20 ft. Actually kind of made a cocoon really. You didn't say anything about the walls. You have open soffits?
Icynene is really the best way to go. Or its equivalent.
Had fiberglass before the icynene and the before after difference was night and day.
Handyman, painter, wood floor refinisher, property maintenance in Tulsa, OK
Be sure to check with the BCO about the 15 min fire barrier. If it is only necessary to cover the exposed interior with DW you can plan on that.
If all exposed foam needs to be covered( no air space ), even in the attic space, that is a much more expensive proposition. It usually requires using a fire barrier paint.
Material cost is in excess of $1 a square foot plus installation and certification where required.
Garett
Truss or stick roof? Solid or skip sheathing?
In any case, with only a 3-foot "attic", you might as well just put drywall on the ceiling and be done with it. With skip sheathing you'll probably get enough airflow through the tile to ventillate the "attic" (in "cooperation" with open or vented eaves). If solid sheathing you may need some alternate ventillation scheme.
(Of course, if you spray foam right against the bottom of the roof you'll have the equivalent of solid sheathing.)