Originally Posted by 84Scrambler
I would have to think it could take 2-3 days or more to heat a slab in a barn to the point it would be comfortable in winter.
depends whjat you consider "comfortable". 50 degrees in my house is cold, but 50 degrees in the garage in the winter is comfortable to me if you are moving.
But you are right, once you start adding heat to the concrete slab, you aren't going to notice ANY difference for 12+ hours, so you either have to plan ahead, or just keep it at a descent temp.