Keep looking. The National Wood Flooring Association ought to have some good information for you.

Not tongue in groove flooring? Exactly then, what is it he wants to sell you?

Also, I'm a bit confused...is it solid wood flooring or engineered? If it's engineered, it won't matter much what specie the top layer happens to be.

"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 for the great information ... and questions. Here's what I can tell you. The engineered planks my GC is talking about are 5/8" thick. I think he said they were 2-1/2" wide. We told him we wanted narrow planks because of the radiant heat when we were considering solid wood. I don't think my GC has much experience with radiant flooring although he has done wood in other situations. My concern about needing to lift the wood is solely in case there's an issue with the heat and we need to get to it. It won't be accessible from underneath because it's panels, not individual tubes. Originally my contractor was going to use a flooring dealer to install and finish the floors. Now it seems he wants to save some money by doing the installation and finishing himself. Makes me a little nervous but I don't think I have any control over it. Thanks, again.

I never heard of engineered planks as flooring that come without tongues and grooves, so I am puzzled. Not sure what your contractor is talking about.

A flooring specialist would be the best choice here, but that is dependent upon what your contract states. Flooring and its finishing can require the right tools, good finishing products and the skill level to get an acceptable result.

I hope it all works out to your satisfaction.

Thanks - i'm a bit confused, too! My contractor is not the most articulate guy. He said it just goes down like planks with face nails or glue. Not "click" together. My problem is that while manufacturer's will say their products can be used over radiant heat, they don't talk about the R-value of it (and if it will insulate against the heat) or whether there is any potential for off-gassing with glues. I'm learning that while something may be sustainable and "green" it is not necessarily good for our health.

Thanks - i'm a bit confused, too! My contractor is not the most articulate guy. He said it just goes down like planks with face nails or glue. Not "click" together. My problem is that while manufacturer's will say their products can be used over radiant heat, they don't talk about the R-value of it (and if it will insulate against the heat) or whether there is any potential for off-gassing with glues. I'm learning that while something may be sustainable and "green" it is not necessarily good for our health.

This is very old and I'm not sure if you are still even around, but what did you end up and are you happy? We're dealing with the same thing.