Should I Insulate My Ducts?

LESLIE: Now we’ve got René in North Carolina looking to talk about duct work. What can we do for you today?

RENÉ: I have some older rental properties. And I noticed on one there was maybe seven duct lines – air-conditioning and heating duct lines – and about half of them were insulated. I wanted to know if I should insulate those that weren’t and what the impact is, maybe, on the bills for the tenant.

TOM: I see you’re in North Carolina. Do any of these ducts run through a finished basement or crawlspace or any place where condensation on the ducts could be a problem for you?

RENÉ: They’re in crawlspaces.

TOM: OK. Well, insulating the duct does make it more efficient. And typically, today, when you install new ducts, you use an insulated flex duct, so the insulation is kind of already built in. When you have air-conditioning ducts that run through very damp spaces like crawlspaces, the other advantage of having insulation is that you don’t get the condensation, which can be quite dramatic. You can really build up quite a bit of water in a damp crawlspace by running a cold duct through it.

So, if it’s already insulated, I don’t feel any need for you to take that off. Do you have to insulate any ducts that are not? I’d say at a case-by-case basis I would make that decision.

RENÉ: OK. And what’s the impact of that? Would they – do they feel an effect of that with the bill – with the heating bill?

TOM: I think there’ll be some effect. Whether it will be dramatic, I doubt but I think it will be somewhat effective.

RENÉ: OK. So all in all, it’s a good thing?

TOM: Yeah, all in all, it’s a good thing. If you’ve got the insulation, I would leave it. If you don’t have insulation, I wouldn’t necessarily add it. Does that make sense?

RENÉ: OK. I’ve gotcha.

TOM: Alright, René. Good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.