How do I Manage Moisture in my Igloo?

LESLIE: Alright. Now we’re going to remote Alaska where Lonnie has an igloo question. I don’t think we’ve ever talked about an igloo.

LONNIE: OK. Well, we have the opportunity to purchase a monolithic dome, which is – it looks like an igloo.

TOM: Oh, OK.

LONNIE: And when we were touring it – it’s only a 20-foot in diameter. But they did have a dehumidifier inside. And on the outside, it had just been painted with a – like a vinyl paint. A thicker paint? And there were bubbles on the outside. And I took a knife and poked it and water drained out. So I’m wondering if there’s a condensation problem, especially for mold, and what it would take to remedy that.

TOM: So what is this dome constructed out of? Is the entire thing concrete or what’s it made out of?

LONNIE: It is concrete.

TOM: Well, listen, you’ve got to have some sort of a system to try to manage moisture in a space like that. Because let’s face it, first of all, concrete is very hydroscopic. So water that will get into that concrete at the base, where it comes in contact with the soil, it’ll draw up into the concrete surface and essentially saturate the entire thing. If there’s bad drainage, it can get worse. But I could definitely see how it would stay very, very damp.

The moisture that you are seeing inside that paint is clear evidence of the fact that this structure is holding a lot of water. Now, it could draw it from the soil or it could just be from the humidity in the air that’s getting into the walls. So, it definitely has to be managed and it sounds like just a dehumidifier by itself may not be the answer. You might need to really have an HVAC pro design a system that could manage that moisture.

And in terms of the paint itself, you also have to choose a paint that is designed to stick well to concrete. You mentioned this is a really thick paint. We’ve seen a lot of paints out there that claim to be sort of almost like a liquid siding that are very thick. But the problem is that they’re not vapor-permeable, so they don’t breathe. As a result, everything stays underneath it and then when you see those bubbles and the water is just forming right there, it’s just going to continue to push that right off. And I imagine when it gets really, really cold, it’ll probably freeze and expand and crack that paint, basically making it worthless.

So I think you have reason to be concerned. And I would definitely – if there’s a good, professional home inspector in that area that could look at it for you, that might be a pro to start with. But I definitely think you’re going to need to have an expert design a system that works for that.

You know, typically, when you paint concrete, you want to use an epoxy-based paint that has really high adhesion and really strong durability. But it sounds to me like this paint that they used, in this case, was not that type of paint.

LONNIE: OK. Thank you so much. I appreciate it.

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