To me, a heated shop is really important. When I think of working in the shop, especially after hours, I would find a heated shop most inviting. I am in the midst of starting to build a small shop, and what I am doing is installing a “radiant hot water in floor heating system” fired by gas.

This works well in a new construction situation, but as Bob mentioned, if your shop is already built, you might not want to go the distance with this type of heating. Although you could get away with a two inch concrete slab over concrete, which really wouldn’t be all that much more cost over new construction, probably about $1,500.00 plus the heating system itself. The problem would be that you would have to remove everything from the shop for a week or so.

To my thinking, “in floor radiant heat” has some serious advantages in a shop. First of all, it heats from the bottom up, which means the area where you are working has priority. This is in stark contrast to forced air heating.

Furthermore, if ever you need to lay down on the floor, you might not want to get up, cause it will feel so user friendly. This is very significant. I believe that a lot of illnesses and back aches etc, come from men not taking care in the area of keeping one’s body warm. A recent study showed that those people who kept their feet warm, were far less likely to catch a cold, flue etc.

Now take into consideration the fact that no air is being pushed around = no dust or paint movement to areas which you might not want to contaminate or dust on your new paint.

In all other forms of heating, the air closest to the ceiling has to be heated before the lower air is warmed. The heating works from the top down, even with those electric and kerosene heaters which you mentioned. Yes, they are positioned on the floor, however given a short distance away from the heaters, the floor and the air remain cool.

Add to all this, if your shop had no insulation in the ceiling, it wouldn’t make a huge difference with “in-floor-heating”. Why? Because a “radiant-in-floor-heating-system’s” priority is within the fist eight feet of the floor. Of course there will be some heat loss, but not to the degree as those systems which have to heat the upper eight feet first to about 80 degrees before the floor’s air even hits 50. An “in-floor-system” would heat the floor to say 60-65, (which is really all you need at the floor in a shop) and the air at the 12 foot ceiling mark might only hit 50-60 at that point. Given a few hours, the air next to the ceiling would obviously warm up.

The other thing to take into consideration is this. Once the slab of concrete is warm, it becomes a thermal mass and takes hours to cool off. So what I’m going to do is have a programable thermostat which will start the heat an hour prior to start-up time and shut if off three hours before shut down time.

As for which type of fuel you might choose to heat the floor, this would depend on the fuel costs in your area. A gas boiler is usually cheaper but an electric boiler might be less costly over the long run.