silverram323
Active member
Where are them pics? I found your post because a contractor wants to use the 3/8” air bubble aluminum pad. I want to use 2” foam board.
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Radiant Insulation - Did I get screwed?
- Thread starter mopar440_6
- Start date
Where are them pics? I found your post because a contractor wants to use the 3/8” air bubble aluminum pad. I want to use 2” foam board.
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Randy in Maine
Well-known member
You might want to just look for a better contractor.
silverram323
Active member
Randy in Maine
Well-known member
I got lucky here when I built my little 40x28 garage/woodshop. The local building inspector was helpful in educating me on selecting SIPs for fast and super efficient construction. Mine are Murus.com SIPS.
My local excavator guy pointed me to a really good concrete guy that normally builds "car dealership" places and did mine when he had some dead time. When you do a SIP building the concrete has to be pretty level at the stem walls. Mine was within about 1/4" high to low. Rebar was not required in my case but I have 6"x6" woven wire that the 1/2" pex is clipped to. I used the 'fiber" concrete and 4000 psi. They cut the "expansion joints" the day after they poured the concrete to minimize cracking.
Seeing how it is colder than death in MN today, I would likely use 4" of foam on top of well compacted fill and a vapor barrier for the heated floor and at least a 2" foam thermal break at the stem walls to the unheated exterior walls. Mine is only 2" foam under the slab, but I rarely see much below zero weather.
My shop is really tight and well insulated though. My wife's next husband will be pleased with it. Way over built.
My shop is only about 20 feet from my house so I just pump warm water (120º) from my house propane condensing boiler underground in 3/4" pex out to the shop that I keep about 50º (air temp). Cheap to heat and no source of flame in the shop.
My local excavator guy pointed me to a really good concrete guy that normally builds "car dealership" places and did mine when he had some dead time. When you do a SIP building the concrete has to be pretty level at the stem walls. Mine was within about 1/4" high to low. Rebar was not required in my case but I have 6"x6" woven wire that the 1/2" pex is clipped to. I used the 'fiber" concrete and 4000 psi. They cut the "expansion joints" the day after they poured the concrete to minimize cracking.
Seeing how it is colder than death in MN today, I would likely use 4" of foam on top of well compacted fill and a vapor barrier for the heated floor and at least a 2" foam thermal break at the stem walls to the unheated exterior walls. Mine is only 2" foam under the slab, but I rarely see much below zero weather.
My shop is really tight and well insulated though. My wife's next husband will be pleased with it. Way over built.
My shop is only about 20 feet from my house so I just pump warm water (120º) from my house propane condensing boiler underground in 3/4" pex out to the shop that I keep about 50º (air temp). Cheap to heat and no source of flame in the shop.
Innovate1
Well-known member
I see several posts mention 2" thermal break at the slab edge where it meets the foundation wall. That's the way I am planning to do mine but had to insist on it a couple times with the plans guy. He kept doing less and saying "that's how it's normally done." He called out expansion joint filler for the thermal break at one point - better than nothing but not that great. Mine has a foundation wall above the floor so planned to run the foam to the top of the foundation. Do I need to worry about the slab shifting? The slab will have a bit of slope to it - about 4" in 40'. I thought about putting in a few 2" plastic blocks but not sure what material I would use.
I don't plan to do radiant heat but did do foam clear across the floor. Original plans only showed 4' around the edge.
Don't know of an easy/good way to get a thermal break at the OHD. Guess I will just have to live with that loss.
I have had people pitch the bubble wrap before. Makes no sense. They do it because it's cheap and easy for them like others have said. And the foil on the foam isn't going to add anything either because it isn't going to face air in this application. It's conduction here so a radiation barrier does nothing.
I don't plan to do radiant heat but did do foam clear across the floor. Original plans only showed 4' around the edge.
Don't know of an easy/good way to get a thermal break at the OHD. Guess I will just have to live with that loss.
I have had people pitch the bubble wrap before. Makes no sense. They do it because it's cheap and easy for them like others have said. And the foil on the foam isn't going to add anything either because it isn't going to face air in this application. It's conduction here so a radiation barrier does nothing.
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silverram323
Active member
Randy in Maine
Well-known member
You will be fine. Good compaction of the base material is money well spent
BadgerBoilerMN
Well-known member
Bubble wrap can be 100% vapor barrier and nearly 100% radiant barrier if separated by air from the exterior. As for insulation. LOL I think most roof rafters should be lined with it because of it's radiant reflectivity. I used Thermax in my pole shed.