I have a 3 season porch with the floor about 3 ft off the ground that I want to make into a 4 season room. I have put 3inch styrofoam between the floor joists, and filled any gaps with foam insulation (from a spray can). Do you think this will give adequate insulation for the floor in South Dakota? Or is there something more I should do?

Another layer of insulation spanning across the face ( bottom) of the joists, and build a skirt around that 3' elevation and close that in with a panel so wind doesn't blow through.

What's your climate and soil conditions?

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