building a 50x60 polebarn and putting in radiant floor heat. not sure what insulation and vapor barrier combo to go with... anyone have first hand experience?? the crete heat things look pretty simple but want to make sure I'm not missing anything if I decide to go with that.
Radiant floor insulation
- Thread starter darrick
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so I read more and realized that the crete heat boards are VERY expensive. it'd cost a fortune to put that down. going with the other type. I noticed that the rfoil goes to like r3.8.... is that sufficient ? if yes then I would just need that, the wire mesh, pipes and ties correct?
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so the more I read the more questions I have..... that rfoil from what I'm reading is not sufficient enough as insulation and vapor..... I was looking at those 2" and 4" Styrofoam boards. good?? bad? do I need a vapor barrier and that Styrofoam ? not looking to go cheap but don't want heat loss too much.
The right thing to do in a MI climate is to put 3-4" of rigid EPS under any radiant slab. The slab isn't holding up the building, so just about any grade of EPS will do, as long as it's layed over a 4-6" of compacted gravel, with a 6-10mil polyethlene sheet for a vapor barrier between the EPS and concrete.
To take the sting out of the wallet, use reclaimed roofing EPS- any grade will do Type II (1.5lbs per cubic foot nominal density) would be great, but Type-VIII (1.25 lbs density, and very common for roofing foam) also works. Make sure to use only polystyrene (EPS or XPS), and NOT polyisocyanurate, which is another common roofing insulation. Polyiso is great for above-grade applications, but can become waterlogged under slabs, or in contact with soil. The cost of reclaimed foam tends to run between 1/4 & 13 the cost of virgin stock goods.
Foam reclaimers often advertise in places like this:
https://detroit.craigslist.org/search/sss?query=rigid+insulation
https://annarbor.craigslist.org/search/sss?query=rigid+insulation
https://grandrapids.craigslist.org/search/sss?query=rigid+insulation
Even though polyiso is usually what's listed, most of the vendors who trade in reclaimed polyiso have access to used or cosmetic-blem reject EPS foam at super-deep discounts.
When installing foam board under slabs it's better to have two layers, taping the seams, with the seams staggered with at least a foot of overlap. Some radiant installers prefer XPS due to it's better retention of the staples used for holding the tubing in place stapled directly to the foam but it's not really a big deal as a one-off for a DIYer to use even Type-VIII EPS. If you're tying it to wire mesh propped up an inch or two off the foam there is really no difference at all.
To take the sting out of the wallet, use reclaimed roofing EPS- any grade will do Type II (1.5lbs per cubic foot nominal density) would be great, but Type-VIII (1.25 lbs density, and very common for roofing foam) also works. Make sure to use only polystyrene (EPS or XPS), and NOT polyisocyanurate, which is another common roofing insulation. Polyiso is great for above-grade applications, but can become waterlogged under slabs, or in contact with soil. The cost of reclaimed foam tends to run between 1/4 & 13 the cost of virgin stock goods.
Foam reclaimers often advertise in places like this:
https://detroit.craigslist.org/search/sss?query=rigid+insulation
https://annarbor.craigslist.org/search/sss?query=rigid+insulation
https://grandrapids.craigslist.org/search/sss?query=rigid+insulation
Even though polyiso is usually what's listed, most of the vendors who trade in reclaimed polyiso have access to used or cosmetic-blem reject EPS foam at super-deep discounts.
When installing foam board under slabs it's better to have two layers, taping the seams, with the seams staggered with at least a foot of overlap. Some radiant installers prefer XPS due to it's better retention of the staples used for holding the tubing in place stapled directly to the foam but it's not really a big deal as a one-off for a DIYer to use even Type-VIII EPS. If you're tying it to wire mesh propped up an inch or two off the foam there is really no difference at all.
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