Spray foam for concrete ceiling under porch?

[Innovate1]

House has a 8 x 18 room under the porch. Hollow core planks with EPDM membrane and concrete porch poured over that. No leakage from outside but we get some moisture on the ceiling in the cold winter months from condensation. Wanting to insulate just the ceiling and 12-18" down the walls to isolate it thermally from the temp extremes but leave the rest. Seems like the insulation needs to include a good vapor barrier or any moisture will get to the cold concrete and result in mold. Was thinking of 2" rigid foam board and then seal around the gaps and edges with canned spray foam. But thinking have someone spray foam (closed cell) the ceiling would be even better. It would be a small job for a company that does this. I have no idea what this typically costs. Is this practical? Guess I need to call around and get a few quotes.

After insulation I plan to put some framing for a ceiling below that with drywall or some sort of good looking covering. Suggestions on that would be great too.

 

[dcg9381]

It would be a small job for a company that does this. I have no idea what this typically costs. Is this practical? Guess I need to call around and get a few quotes.

Spray foam is one of those jobs that you typically can't DIY for cost. Cost is regional. This is a "small job" and you might be able to get it done as a one-off on larger job. But as it's right on the margin if you can't get a deal, consider DIY:

https://tigerfoam.com/order-products/spray-foam-kits/

Make sure you cover the floor under the roof deck.

After insulation I plan to put some framing for a ceiling below that with drywall or some sort of good looking covering. Suggestions on that would be great too.

T-111 is cheap and pretty easy. I wouldn't do drywall... But that's just me.

 

[Innovate1]

Spray foam is one of those jobs that you typically can't DIY for cost. Cost is regional. This is a "small job" and you might be able to get it done as a one-off on larger job. But as it's right on the margin if you can't get a deal, consider DIY:

https://tigerfoam.com/order-products/spray-foam-kits/

Make sure you cover the floor under the roof deck.

T-111 is cheap and pretty easy. I wouldn't do drywall... But that's just me.

Are you saying a company might do it if they could combine it with another nearby job? Not clear on what you said...

I did 1/2" plywood on the walls of the detached garage and covered the joints with thin trim strips so that's a possibility. 7/16 or even 3/8 should be plenty for the ceiling as it won't have any load other than it's own weight. Easy enough to do 16" centers on the joists. A bit less than 8' span so 2 x 4 should be plenty. Was thinking surface mount lights but could do recessed about as easily. We are going to market it as a wine cellar when we eventually sell (which isn't any time soon).

 

[dcg9381]

Are you saying a company might do it if they could combine it with another nearby job? Not clear on what you said...

Yes. Possibly. Get a few bids and then compare to tigerfoam

I did 1/2" plywood on the walls of the detached garage and covered the joints with thin trim strips so that's a possibility. 7/16 or even 3/8 should be plenty for the ceiling as it won't have any load other than it's own weight. Easy enough to do 16" centers on the joists. A bit less than 8' span so 2 x 4 should be plenty. Was thinking surface mount lights but could do recessed about as easily. We are going to market it as a wine cellar when we eventually sell (which isn't any time soon).

 

[Innovate1]

Wondering how much temperature affects the job. Was hoping to get this done while temps were warmer but here we are in December with temps around freezing. The contractor said they could do it down to surface temp of 32 (which shouldn't be a problem) but no moisture. Condensation could be an issue as that's one of the reasons I want some insulation. It's only been a problem in one small corner so I suppose I could put a portable heater there. If the weather forecast doesn't call for precipitation I might throw a moving blanket over the outside.

 

[fitter30]

Wondering how much temperature affects the job. Was hoping to get this done while temps were warmer but here we are in December with temps around freezing. The contractor said they could do it down to surface temp of 32 (which shouldn't be a problem) but no moisture. Condensation could be an issue as that's one of the reasons I want some insulation. It's only been a problem in one small corner so I suppose I could put a portable heater there. If the weather forecast doesn't call for precipitation I might throw a moving blanket over the outside.

Take some plastic sheeting duct tape to the cement pad all the way around. To see id the sweat is coming from the pad or inside.

 

[dcg9381]

It's only been a problem in one small corner so I suppose I could put a portable heater there. If the weather forecast doesn't call for precipitation I might throw a moving blanket over the outside.

I don't think you want to be spraying foam while heating with a small heater. Daytime temps - you should be able to find a day that works for the application per the installer.

I'm a little concerned about condensation in one corner. Are you sure it's condensation and not a leak? Closed cell will mask leaks, redirect the water and make those sorts of things hard to find.

 

[Innovate1]

I don't think you want to be spraying foam while heating with a small heater. Daytime temps - you should be able to find a day that works for the application per the installer.

I'm a little concerned about condensation in one corner. Are you sure it's condensation and not a leak? Closed cell will mask leaks, redirect the water and make those sorts of things hard to find.

I was trying to get it done this year as the tax credit for insulation expires this year. But I have too much else going on and it's cold so think it will wait until it warms up in the spring. It's not leaking. I put EPDM sheet over the hollow core before I had the porch poured over that. It's just that the cooler concrete causes a bit of condensation - at least I think that's what it is. I looked at it recently and noticed the darker discoloration isn't damp and doesn't extend to the wall support - it ends about 1/2" short. It could be the hollow core is slightly cooler than the wall but that doesn't quite make sense to me based on the complete pattern. I will try to get a pic.