I have a 12x24 storage shed outside. I live in Georgia and the shed has a metal roof so it gets HOT in there. The shed has 2 vents on each end, but they don't seem to do much. I think the metal cap on the ridge has foam in there so critters can't get in, but I can't see in there to be sure. So no heat is escaping out the roof. I want to insulate the building, but I'm not sure which would be best. Should I run ceiling joists across the top plate, drywall it and then blow insulation in up there or should I try to stop the heat before it even gets in by putting styrofoam panels directly up against the metal roofing? Eventually I will put batts in the wall and drywall the whole thing, but my main concern is the roof right now. Any ideas? Thanks.

Pat

I'm assuming an angled ceiling is not an issue. Is condensation an issue? You could put bats or foam between the rafters, they may stay there without much support depending upon size and you can then put batterns in to support the ceiling and the insulation or you can put in a conventional ceiling by putting in horizontal rafters to support it and insulate as you put up the ceiling panels with foam or bats. From this you may have gathered I'm not a fan of bloan insulation

Insulate it to keep the heat out?

If you were planning on spending time in this thing then I can understand making it comfortable, but that kind of expensive to keep the lawnmower and rakes cool? They make portable fans for spaces like that.

Well, I do spend some time in there as I have a work bench in there. I also store some stuff in there that I don't want getting that hot. It's gets over 120 in there sometimes and that's going to possibly hurt some stuff I'm storing in there. And I'm not stuck on blown insulation Paraclete, I can roll out ceiling batts in there. I just didn't know if it was more efficient to insulate the current metal roof itself or drop a ceiling in there and insulate over that leaving the dead air space in the top. In my other shop that is about 20 x 10, I put in a standard ceiling and left an access panel near each end. Then rolled out OC attic blanket that was maybe R-30. I'm not sure about condensation... there's none now, but I don't know if either choice will create an issue. I don't think the "standard" ceiling will. And yes, I was talking about running ceiling joists horizontally from wall top plate to top plate, not putting them up there on the roof rafters.

Insulation alone will not help that much, you need air circulation. A ridge vent would help but you also need to let fresh air in lower than the ridge. A few vents near the floor would help the ridge vent or even offer venting.

I know that this is an old post

BUT

What you would have is a ridge cap, not a ridge vent. A ridge cap simply keeps the rain out at the peak of the roof. Yes, it can get hot in Georgia in the summer time in a building with a metal roof.

If'n it wus me,
I'd get the smallest thermostatically controlled attic exhaust fan I could find. Install it first because you won't be able to walk around on the roof to do it. Install it high up on the roof close to the center. Run you ceiling joist 24" on center. It looks like you have a 12' by 16' shed. Stuff your bat insulation up between the joist. Paper side down. The insulation bats should stay in place when simply stuffed in. Don't have to tack to the joist. I wouldn't go over board with the insulation. It will help some but not that much. As Bob said it is the ventilation that counts. Heat tends to rise. If your insulation bats don't want to stay in place, run about 3 or 4 nylon strings across the bottom of the joist. Tack to bottom of each joist. Then put your insulation in. A lot cheaper and easier than trying to blow insulation in.

I am assuming what I see in the end panel near the peak is a vent and not Plexiglas light panel. If not replace it with a louvered vent.

If you really want to be comfortable put a small air conditioner through the wall.