I'm not a pro, just a cork fan whose been doing some reading on the subject and collecting samples. So all the following might be wrong: hope a flooring guru will chime in and enlighten us both.

So as I understand it [and just to confuse you even more], the nice people at Duro Design INSIST that you can use their glue downs over radiant.

I *think* that floating planks are usually reccomended for use over radiant because they are more dimensionally stable and the cork layer is thinner, so the heat comes through better [though the difference there has to be minute: we're talking about a roughly 1/8th inch difference between the two, and the floating has a board structure the glue down doesn't]. The Duro glue down flexes a bit, which may be why the 'dimensionally stable' part is less important...

So, if that's the glue down you are looking at, the radiant would probably be fine.

BUT.

I don't remember seeing anything on Duro's website about using it below grade. I think the issue with glue down is that the glue may give way if/when the moisture level of the concrete changes: I think that trumps all.

As to kitchens, I think glue down is preffered because it has more cushion, and no engineered core that can swell irrepairably if it gets wet. Still, the cork floating is no more prone to water damage than other engineered wood floors, and offers more cusion than any wood floor. It is supposed to be very important to keep the urethane seal coat intact, though...

Thanks oruboris... Duro is exactly who I'm looking at. I've heard great things about their product and so far I'm happy with their customer service, at least as far as answering emails goes.

I found information on the below grade stuff on their website, here, section 1.3, letter "a": Duro below grade. I emailed them and their response was "We put this in our spec as a super precaution. There is no problem laying cork below grade as long as there is not excessive hydrostatic pressure. i.e. under 3 pounds per 1000sf using the calcium chloride test. This is a standard test for flooring."

Now, I'm not exactly sure what hydrostatic pressure is, but I'm guessing it has something to do with the amount of moisture being released from the slab. Since we're doing everything possible to be sure the slab is dry (it's our main living space) I'm assuming we'll be ok using the glue down tiles.

So, my only remaining concern is the radiant heat. It was my understanding that the floating floor is better over radiant because when it expands/contracts, the floor does so as one solid piece rather than as each individual tile would in a glue down situation (causing gaps), which makes sense to me. However, after looking through some old emails, you're right, they claim that both glue down and floating can be used over radiant. I'm not sure what they're saying with glue down then... maybe they don't expand/contract much if acclimated properly before installation?

Ugh. So confusing!