Does a heated slab need insulation under the slab?
I live in Alaska and I am building a heated slab foundation, The lot I am building on is a good gravel base after removing the top 1 to 2 feet of top soil. I am being told two different stories by two different contractors. One says I need 1″ to 2 ” of insulation under the slab and the second says the good gravel base is better and will keep things warmer once it reaches temperature. I visited a shop today with a heated slab and no insulation except on the perimeter and it was warm and was heated with a hot water heater. I want to do it right but don’t want to waste money.
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