I have an advanced case of the owner builder disease -- grand ambitions -- and need help with compromising radiant heat and soundproofing. The basics first.

This is the second floor with advantech subflooring in place and a finished downstairs, meaning nothing is possible under it. The hardwood is well-seasoned 3/4 oak plank. The radiant, using transfer plates, requires a second subfloor a half inch thick. The footfall transfer so far is atrocious. A pair of playful 12-pound kitties have inspired us to coin the phrase "thundering cats."

The limitations as I understand them: You can't use glue in a radiant build up; nailing a solid wood floor through soundproofing substantially degrades same; floating floors have sound issues of their own although interfloor transfer is my only focus. Thoughts or experience with any of the above greatly appreciated.

I have two preliminary approaches:

Nail the floor through half-inch cork, accept the tradeoff between less effective soundproofing and more effective heat, and throw down rugs in high traffic areas.

Lay down mufflerfloor or similar; use yellow pine or similar dense wood for the second subfloor (cheap as plywood here in Mennonite country) and use short screws and glue to build a two-ply floating floor. Then worry that the weight and resulting compression degrades the soundproofing.

Thanks in advance for your thoughts or suggestions. My advice to owner builders, worth full price, is keep it simple, Stupid.

I pressed on regardless and discovered two bad assumptions floating out there. You can glue over radiant. Warmboard, the aluminum clad subfloor manufacturer, has several recommended glues on its site that are highly flexible and water resistant (to limit and handle expansion and contraction.) I used Bostik's Best -- not a squeak anywhere and reasonably friendly to use. For polyurethane anyway.

And half-inch cork substantially reduces impact noise even with moderate penetrations by fasteners. (I used finish screws to stay out of the glue.) I spaced them 12 inches on center to pull the oak planks into the glue. I put a quarter inch plywood underlayment between the cork and the hardwood rather than gluing directly to the cork.

Floating engineered hardwood would be easier and more effective. I'm not sure why contractors don't make more use of cork for radiant via transfer plates under the finished floor. You need the build-up anyway and cork gives you sound proofing and R3/inch.