Installing Radiant Heat Under Two Layers of Flooring
LESLIE: Talking to Carl in New Jersey about radiant heat. Tell us your question.
CARL: Yeah, I have a problem. I have a 108-year-old house and, basically, we’re trying to redo the outside. It has no subflooring, so it just has the tongue-and-groove right on the floor joists and there was a porch that came off of it and we put some subflooring to kind of match and there’s no way for me to get any heat in that area. I was going to do baseboard heat but I like the radiant heat.
TOM: In the porch area?
CARL: In the whole house area because I’m …
TOM: Whole house. OK.
CARL: Yeah, the house is old and we’ve looked at doing this floor and to redo it with 108-year-old there’s some boards that have to be replaced that I want to put in.
CARL: My question is this: can I put ¾-inch board on top of another ¾-inch and have the radiant heat underneath?
TOM: Yes, you can.
LESLIE: Does it depend on the manufacturer type of radiant heat where they go? Because I know some are made to go …
TOM: Well, you’re probably going to use a PEX system, which is cross-linked polyethylene piping, and part of that system is designed to basically go – sort of be inserted into a subfloor. The only downside of this is that you’re going to be raising the height of the floor across the whole house by that three-quarters of an inch that it would take to contain the PEX.
CARL: I have a nine-foot ceiling.
TOM: Ah, so you have plenty of room to go up. Yeah.
LESLIE: (overlapping voices) Oh, then you’ve got the space.
CARL: Yeah, there I do but my dilemma is the porch that I had that was concrete slab and then we put – you know, it was a step-down. We built it up and it was only maybe four inches. How do I get heat there? The only way I can think about to not raise the floor any higher is putting electric but then I need a floating floor.
TOM: Well, why don’t you combine radiant heat with some baseboard units in the places that you can’t get the radiant heat to go? They could all run off the same boiler.
CARL: Yeah, but do you think that with the not having a subfloor the ¾-inch tongue-and-groove on top of another ¾-inch tongue-and-groove will produce enough radiant?
TOM: Well, it’s not the depth of the wood that’s the issue, OK? If you have the hydronic heating pipes inserted into that upper subfloor you’re going to get plenty of heat and you will be quite comfortable; especially your feet.
CARL: Well, thank you.
CARL: Thank you very much. I appreciate …
TOM: You’re welcome. Thanks so much for calling us at 888-MONEY-PIT.