DrVlikhell
Active member
TLDR: Looking for ideas to better insulate a metal pan roof under the extreme heat of the South Florida sun, including spray foam and/or rigid foam board.
I have a metal pan roof over an extra room added onto my house for a utility/shop room. This particular portion of roof has the top caps over the pans with what looks like a 1.5 inch or less piece of styrofoam for insulation in there. Below are some pictures of the style of roof I'm talking about, except in these pictures the styrofoam takes up the entire space where in my roof it's half that thickness with the rest open air and a mystery extra piece of sheet metal in there. I would like to improve on the insulation because, in summer, the ceiling of that room reaches 110 degrees in some areas, even with a thick covering of pine needles on the roof. There is no crawl space for insulation because the bottom of the pan roof is the ceiling of the room.
The "correct" way would be to remove all of the pan tops and replace the thin pieces of styrofoam with some properly thick pieces like they have in the pictures. There are three problems with this. One, the only local shop that has 12 foot styrofoam bits wants $80 each for them and I would need 16 pieces. It would pain me greatly to pay $1300 for frickin styrofoam blocks. Problem two, is that I'd have to unscrew all of the pan tops which would invite leaks. Problem three is that this type of pan roof I have will not support the weight of an adult and I don't have any kids, so I would have to build a scaffolding over it in order to remove the pan caps. The styrofoam can't be slid in/out at the end because mine has a gutter blocking them which can't be removed because it's molded into the end of the pan.
So I was thinking... what if I filled the remaining air space with spray foam? I've seen several people use spray foam as insulation on tiny house builds as well as RV/van/camper builds. I don't necessarily mean spray foam in a can, but I've seen spray foam in canisters the size of propane canisters with a hose and gun. I would still need to build a scaffolding to get over the roof to open up the roof pan caps, but the benefits over just using a piece of styrofoam would be that a closed cell foam would help prevent future leaks, and with spray foam stuck to all sides in there, it would also help with strength and rigidity in storms (I live in South Florida so this is important).
Alternatively, I could use some rigid foam board, cut it to fit, and put that in there instead of buying the specific pieces that are made to size for my roof. This would be a lot cheaper, but I think that may not be a good idea because the ends of the roof are open to the elements and I don't think rigid foam boards are meant to put up with that.
My other idea (in addition to or in place of the above idea) is to use 4x8 foot rigid foam boards and glue them to the ceiling. I can't afford to loose much height by lowering the ceiling a lot, but even a 1" rigid foam board could get me an R value of 5 or 6, which isn't much but it's better than 0. Of course if I did both ideas I might end up with an overall R value of almost 20. The roof can't support much weight, but a 4x8 sheet of rigid foam board only weighs about 5lbs and I'm sure there's more than 5lbs of pine needles up there.
The length of the pans is 12ft and there's 16 feet of them that are capped. There's more pan roof after that without top caps... but I'm not worried about that section yet.
Below are two example pictures of a metal pan roof with the pan caps and the last picture is of what's inside mine. I have no idea what that extra piece of sheet metal is above the styrofoam in my roof.
Any suggestions, ideas or input would be very welcome. I've got to do something with it before the brunt of summer. It's already affecting the performance of my new AC and it's only March.
(Similar to mine but with much more styrofoam than I have)
(Inside my roof between the pan and top cap)
I have a metal pan roof over an extra room added onto my house for a utility/shop room. This particular portion of roof has the top caps over the pans with what looks like a 1.5 inch or less piece of styrofoam for insulation in there. Below are some pictures of the style of roof I'm talking about, except in these pictures the styrofoam takes up the entire space where in my roof it's half that thickness with the rest open air and a mystery extra piece of sheet metal in there. I would like to improve on the insulation because, in summer, the ceiling of that room reaches 110 degrees in some areas, even with a thick covering of pine needles on the roof. There is no crawl space for insulation because the bottom of the pan roof is the ceiling of the room.
The "correct" way would be to remove all of the pan tops and replace the thin pieces of styrofoam with some properly thick pieces like they have in the pictures. There are three problems with this. One, the only local shop that has 12 foot styrofoam bits wants $80 each for them and I would need 16 pieces. It would pain me greatly to pay $1300 for frickin styrofoam blocks. Problem two, is that I'd have to unscrew all of the pan tops which would invite leaks. Problem three is that this type of pan roof I have will not support the weight of an adult and I don't have any kids, so I would have to build a scaffolding over it in order to remove the pan caps. The styrofoam can't be slid in/out at the end because mine has a gutter blocking them which can't be removed because it's molded into the end of the pan.
So I was thinking... what if I filled the remaining air space with spray foam? I've seen several people use spray foam as insulation on tiny house builds as well as RV/van/camper builds. I don't necessarily mean spray foam in a can, but I've seen spray foam in canisters the size of propane canisters with a hose and gun. I would still need to build a scaffolding to get over the roof to open up the roof pan caps, but the benefits over just using a piece of styrofoam would be that a closed cell foam would help prevent future leaks, and with spray foam stuck to all sides in there, it would also help with strength and rigidity in storms (I live in South Florida so this is important).
Alternatively, I could use some rigid foam board, cut it to fit, and put that in there instead of buying the specific pieces that are made to size for my roof. This would be a lot cheaper, but I think that may not be a good idea because the ends of the roof are open to the elements and I don't think rigid foam boards are meant to put up with that.
My other idea (in addition to or in place of the above idea) is to use 4x8 foot rigid foam boards and glue them to the ceiling. I can't afford to loose much height by lowering the ceiling a lot, but even a 1" rigid foam board could get me an R value of 5 or 6, which isn't much but it's better than 0. Of course if I did both ideas I might end up with an overall R value of almost 20. The roof can't support much weight, but a 4x8 sheet of rigid foam board only weighs about 5lbs and I'm sure there's more than 5lbs of pine needles up there.
The length of the pans is 12ft and there's 16 feet of them that are capped. There's more pan roof after that without top caps... but I'm not worried about that section yet.
Below are two example pictures of a metal pan roof with the pan caps and the last picture is of what's inside mine. I have no idea what that extra piece of sheet metal is above the styrofoam in my roof.
Any suggestions, ideas or input would be very welcome. I've got to do something with it before the brunt of summer. It's already affecting the performance of my new AC and it's only March.
(Similar to mine but with much more styrofoam than I have)
(Inside my roof between the pan and top cap)
