I am getting a 40x60x14 shop put up in about a month. Its going to be a pole barn building with hydronic floor, 2'' foam insulation under the concrete.

The building contractor spec'd out the insulation as this:

2x6 "bookshelf" in between the poles with 6" batt insulation, with a vapor barrier.

Will this be sufficient? Instead of using a 6 mil plastic vapor barrier, I think I might have them install reflective foil type insulation between the batt insulation and the inside liner panel. Is this a good idea?

I would put http://www.lowes.com/lowes/lkn?action=productDetail&productId=13353-56291-ST16025&lpage=none under the metal roof, to block radiant heating of the batt insulation. Should help in the summer months (next year).

If you have the money have them spray the polyurethane foam insulation. Its the best.

I agree with the spray urethane insulation. The upfront cost will be more but you'll be so glad you did.

Make sure insulation is put on the perimeter of the floor also. 6" seems on the weak side to me. What are going to use to heat the water ? The more insulation the less the BTU needed for heating.

Going to be using an electric boiler with a circulation pump...

Are you using water or glycol?

Going to be using an electric boiler with a circulation pump...

holy expensive to run, have you considered solar hydronic panels?

something like this http://www.solar-components.com/actvdhw.htm

The foil type insulation works good if you follow the install directions. To get the stated R-value reflection you need a certain amount of air spacing. The spray foam works great acts as a moisture barrier, insulation and sound barrier. The electric boiler is an efficient way to heat especially if you can run it on controlled power.

I'm being told 3-4 dollars a day to run once you are up to temp.

Electric boilers are slow in heating up the water. But if your BTU requirement is small then it will not be to bad.

Spray foam would be the way to go it will seal that building up. 1" of two pound spray foam will outperform a 6" (R-19) batt

you should be able to get the vinyl vapor retarder with foil on the back side which shouldn't add too much to the cost.

Here is my spray on insulation as shop was being built. I love it. Everything is sealed. R22 on sidewalls Blown in R40 in ceiling.