"He said it just goes down like planks with face nails or glue." How thick is the product? We do install face nailed wood on occasion, but it is not common. Most of it is 3/8" thick unfinished wood in 2 1/4" strips. It can make for a nice floor. Wood or anything over radiant heat can be a challenge and there is, as you say, little information about R-values and potential off-gassing of engineered products when heat is applied. I refused to bid on a job where I could not get specific information from the architect as to the design of the radiant heat system. If your contractor has experience installing over radiant heat, then I think he will know what glue to use in addition to the nail fasteners. You also say, "It would also make it difficult, I imagine, to remove the flooring if necessary." A wood floor is expected to last a very long time. It is considered to be as permanent a material as is stone. Although it might prove a little more difficult to remove when glue is included, it is doubtful you will ever want or have the need to do that. "Would any kind of floating floor such as Marmoleum block the heat and leave us cold?" I am not a fan of floating floors. However, some people find them acceptable. I will say that, although cork is a decent insulator, heat will make it to the surface. The key thing here is that you want a tight fit between the back of the flooring and the heated substrate. In other words, your substrate needs to be perfectly flat...no birdbaths, no spots where there is poor contact between the panels and the substrate. Keep looking and learning, since that seems to be important to you. And another question for you: You say that you're working with a flooring dealer and then you say "the contractor"...is this one and the same?

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!

We installed Lauzon's Next Step (engineered)flooring about 2-1/2 years ago. It's an excellent product. Our floor is red oak natural and is glued down to the concrete subfloor (not floated)and we do not have radiant heat. We did not use Lauzon's glue, but used Bostik's Best adhesive instead. No problems with adhesion so far. Before we installed, I called their toll free customer service number and asked a few questions. They were friendly and helpful. Lauzon has their installation guide on their web site. I will try and link to it below. I did a copy and paste from their guide that refers to radiant heat. I did not read further, but it would be interesting for you to read. The part I copied: "Before Installation Evaluation of Job Site & Moisture Content: NextStep Collection flooring can be installed over the following subfloors: � Concrete � Existing wood floors � Plywood � Underlayment-grade oriented strand board (OSB) � Vinyl Sheet / VCT � Ceramic tile � Sound barrier � Radiant heat Before installation, inspect the job site thoroughly to determine if the subfloor and conditions are acceptable". If you read the installation guide, you may find some answers to your specific questions. Also, I would not hesitate calling Lauzon's toll free number. Best of luck and keep us informed as to what you discover and what you decide to do! Laurie Here is a link that might be useful: Lauzon Next Step Installation Guide

What is the exact water temperature coming out of the boiler for the loops? Your air temp may be set to 71, but the water in the PEX in the concrete is much higher. You need to know how high, or you'll have floor failure of anything not compatible. For any bonding install, like glue down wood or thinsetted tile, you will need to grind off the surface sealer from the concrete. It won't bond. And, floating floors with a foam underlayment aren't wise with radiant heat either. You don't have a lot of choices, and none of them are really ''soft''. Other than maybe adding some rugs to the existing install.