I know this topic has been beaten up a bit, but I am looking for the proper way to insulate my garage ceiling once my new roof is on. The trusses are scissor type so they are on an angle and high enough that sheet rock will not be a fun project. I was thinking about spray foam, but I am afraid of what the cost to do roughly 1000 sq ft. will be. Also what is the proper way to vent the shop if I do a closed cell foam over the entire ceiling? I would like to end up with an area that is fairly easy to heat once It is completed.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Insulation
- Thread starter jerryd68
- Start date
we are in the process of building a house and they strongly advised against spray foam in the ceiling, even though we are doing it in the rest of the house. reason is, there's enough room to get the same R value using blown of batts, plus if you ever have a problem with wiring for lights, or want to add more, you're screwed if the foam is there.
j p smith
Well-known member
jerryd68
I went with ridge vent at the peak of my roof, bird board screens at the top of the side wall, radiant barrier on the bottom part of the truss on the roof side and 6" batts at the ceiling. My truss' are 5/12 on the roof side and 2 1/2/12 on the ceiling side. The spray foam I have seen is usually right on the underside of the sheeting not the ceiling, am guessing you would still want a ridge vent to go with the bird screens at the top of the wall and spray in loose insulation or batts.
I went with ridge vent at the peak of my roof, bird board screens at the top of the side wall, radiant barrier on the bottom part of the truss on the roof side and 6" batts at the ceiling. My truss' are 5/12 on the roof side and 2 1/2/12 on the ceiling side. The spray foam I have seen is usually right on the underside of the sheeting not the ceiling, am guessing you would still want a ridge vent to go with the bird screens at the top of the wall and spray in loose insulation or batts.
I did a ridge vent on my house but it has a dropped ceiling, I was thinking that I would leave my trusses open and just spray foam the under side of the sheathing, just seems like if I have an open vent in my roof ridge that will not be able to heat it effectively.
j p smith
Well-known member
Jerry, are you putting in a drywall ceiling, if so there should be no issue unless you have openings in your ceiling. jeff
Falcon67
Well-known member
we are in the process of building a house and they strongly advised against spray foam in the ceiling, even though we are doing it in the rest of the house. reason is, there's enough room to get the same R value using blown of batts, plus if you ever have a problem with wiring for lights, or want to add more, you're screwed if the foam is there.
Around here, if you opt for spray foam the house becomes a sealed envelope. That means walls and underside of the roof. The entire interior including attic becomes the conditioned space. My boss' house and several others are done that way. Their house is around 600 more sq/ft than ours, they are 4 (two boys) instead of us 2, they have two 50 gallon water heaters to our one and they use a bit less power than we do. No problems accessing wires and fixtures in that attic, not a stick of insulation anywhere.
And yea, it was damned expensive for their foam during the build. I think around $2 something sq/ft of coverage. Their house is big and has a very high pitched roof (looks 8 or 10 pitch) so they foamed a LOT of sq/ft.
Last edited: