|
| I have a 60 x 120 x 18, built 13 years ago. My Carrier engineer was the only one at that time ( out of 9 other contractors I had talked to ) that did not want me to insulate under the slab. We insulated the inside of the wall with 2" foam board and the outside. Their theory was to prevent cold from coming in and to retain the heat of floor from moving out.
I have 18" of packed 411's under 7" slab ( I needed fill, I think 8" would have been enough ) . plastic sheeting on top of the 411's, then my loops are tied to that, rebar on top of the loops.
Carrier told me that the heat would only travel downward a small amount ( like 6" below the tubes ) and then come up and basically use everything as a "heat sink" or reservoir if you will. I was concerned about the foam board rotting away over time, say like in 25-30 years from now, but I did not want to risk chance of breaking down my floor, so I did NOT insulate the floor. Newer technology today has some very good products out there, I like the looks of foil backed fiber right now, and not just only that.
I normally go thru 1500-1800 gallons of propane from Nov 1 - Apr 1 on a given winter, BUT I am in a warmer winter climate than you so take it FWIW.
I keep it at 65* F pretty much all winter, 3 zones, wash bay, main shop , and office, with the office a little warmer. My doors open a fair amount as I work on machinery, and when I paint, I bump it up a little more.
I have friends that have installed floor heat in smaller shops with insulated floors, and go thru more propane than I do, but I would add to not be afraid to spend money in insulation above ground ( meaning the rest of the building ) either, there are more pieces to the whole puzzle than just the floor heat.
Technology has really moved forward since I built, I considered spray foam, but at that time was concerned of the flamability of it ( since I metal fab a fair amount ) , even with a liner, so I went with 2 vapor barriers, an inner and outer, with fiberglass in between. My building is tight, very air tight, but if doing over would look at spray foam again. Another thing I notice, is in the summer time, my building seems to be and stay cooler inside too.
My point to this, I think it is worthwhile to foam board inside and outside the cement wall, especially if you do not insulate under the slab.
On the flooring, wow, there are a lot more options out there than when I built, so read, ask, learn, what you can before you start, but I am happy so far with how mine performs.
| |
|
Insulating a heated floor.
