Installing Flooring Over In-Floor Heating Systems

Q: I was reading your blog and it, along with the rest of the website, is super helpful.
My boyfriend is building a house on a slab, and the slab has radiant in-floor heating tubes. He is planning on putting ceramic tile throughout the whole downstairs. I hate the way ceramic tiles feel on the feet, especially in a living room. I have been looking into cork or bamboo flooring and my basic question is:
How do bamboo and cork compare to ceramic tile for thermal conductivity. I read that the cork tiles had low thermal conductivity, which sounds like they’d be a bad conductor of in-floor heat. I do not know the status of the bamboo, and would a heated floor cause it to warp or change shape more than it should?
Any answers at all would be great!!! I’d really like to have nice soft floors with no grout!!
Thanks,
Rachel R.
Albany, NY
A: Radiant heat is great in homes, but certain floors perform better over them than others. In the case of wood floors, you will want to stick with floors which are engineered – this includes floating cork and laminate floors. These types of floors are far more stable and are less likely to adversely expand or contract from the heat.
With cork, which is likely to be the most comfortable floor under foot for you. Cork is a natural insulator, which means a certain amount of warmth from the radiant heat system will not conduct through the floor. The good news here is that 3mm of cork will only reduce the amount of heat coming through the floor by 3-5%. This being said, as long as you account for this minor loss in heat, you should still get a decent amount of warmth through the floor.
In the case of bamboo, very few solid bamboo floors are approved for radiant heat, so you would want to look into a floating or engineered product such as those made by Springwood. In the case of the engineered bamboo, you will treat this much like any other floating wood floor and you will want to give it plenty of time to acclimate, then post install gradually increase the heat from your radiant system until it reaches the intended temperature over the process of several days.
End result here is that stone and tile will be the easiest floor to lay down over your radiant heat system, but as long as you account for the proper product and a bit of time to slowly dial up the temperature of the heating system, many wood floors, especially engineered or floating floors, will work nicely.