Best Way to Heat Below Grade Bathroom

LESLIE: Paul in Pennsylvania is on the line and needs some help on how to heat below grade bathroom. What can we do for you?

PAUL: We had an add-on about 30 years ago in this house. It’s actually my childhood home we bought and it’s – but we are changing the – what used to be a mud room into a laundry room and a bathroom.

TOM: OK.

PAUL: With all that plumbing that’s going on in there, we’re trying to find the best way to heat it. The house is on central with a furnace – gas furnace. But I’m unable to get the ducting out there.

TOM: Mm-hmm. OK.

PAUL: Is there another way that might be better than just an electric-baseboard heating?

TOM: So this is just for the laundry room and it’s where – on the end of the house or something, where you don’t have ducts that go that far? Or why is it hard to get them out there? Just explain the layout to me.

PAUL: Floor is actually technically about 10 inches lower than where the foundation is for the house. It’s where it was poured about 10 – or about 30 years ago or so. And the only access point I have outside of the house with that is actually taken up with the drainage and the waste drainage and then also the water.

TOM: Got it. So you really need something to heat below grade bathroom that’s an independent system here is what it sounds like.

PAUL: Yeah.

TOM: And how big is this laundry-room space?

PAUL: The whole area, bathroom and that, is about 14×14.

TOM: I’ll tell you what, even though we rarely recommend this, the least expensive way for you to heat below grade bathroom I think is going to be electric. If you were to put electric baseboard in there on a thermostat that was a timer thermostat, right, one where you could do a setback to it so that you only had that come on when you really needed it – electric heat is the most expensive but you’re talking about a really small space. And anything else that you do there – like we could talk about a mini-split ductless, for example – that’s going to be $2,000, $3,000, $4,000 by the time you’re done putting a compressor outside and a mini-split ductless up on the ceiling – up on the wall I mean.

PAUL: Yeah.

TOM: And it may not – it may be overkill for that small space. So I think if I just had a 14×14-foot space there – 150, 160 square feet, whatever that works out to be – that’s probably perfect for electric baseboard.

PAUL: Yeah. And I should probably not – with that, I shouldn’t even have to really worry too much about pipes bursting or anything. They’re PEX but …

TOM: Right. And you know what? The other thing that you could do is – what’s the bathroom situation now? Do you have a tile floor down? Or what kind of flooring do you have?

PAUL: We actually don’t have any flooring down right now. We just got the floor joists and the ceiling joists in. We’re finishing up the plumbing currently.

TOM: Why don’t you put electric radiant heat under the floor to heat below grade bathroom? Put it under the floor of the bathroom and the floor of the laundry room if it’s not done yet. And if you put it in right, again, it’ll be a very pleasant experience. And if it’s on the right kind of thermostat, you’re not going to have to worry about those costs getting out of control. And boy, there’s nothing better than having a warm floor when it’s chilly.

PAUL: Yeah.