How to Waterproof a Lanai
LESLIE: Now we’ve got lucky lady Nancy who lives in Hawaii, the greatest place in the world, who needs help waterproofing a lanai.
NANCY: Hi. Aloha.
LESLIE: Aloha. How can we help you?
NANCY: Well, we have a walk-around lanai on our home that gets water on it when it rains. And the floors don’t slope, so it’s standing water. And so we’re trying to figure out a way not only to help make a slope but something that’s a waterproof floor that we can put on there to prevent our wet lanai.
TOM: So what’s the lanai made out of now? What’s the floor now? Is it concrete?
NANCY: It’s plywood with waterproof paint.
TOM: OK. So if you want something that’s really super-durable on that floor and you want it to be completely waterproof, I would recommend fiberglass. We very often use fiberglass when we build waterproof decks like, for example, that might be on a second floor where there’s living space below.
It’s kind of like handcrafting the hull of a boat, you know, across that deck surface, because you make it very much the same way. You put it in fiberglass, in resin, in varying layers and the pros will just make it so it’s almost like one complete piece and then it can have an abrasive finish on it so that nobody slips or anything like that. So that’s a really super-durable way to create a deck that you can walk on, push furniture around on and not have to worry about it breaking through or ever leaking.
NANCY: And then there’s a way to make it slope?
TOM: Right. And so what you would do before you did the fiberglass is you would probably put a second layer of plywood over there. And you would build it up using what’s called “sleepers,” which are sort of like long shims, to kind of create the pitch first. And then once you had the pitch established with the wood, you would cover it with fiberglass. And that would actually go up under a bit of the siding where it attaches to the house so that it gives you a complete waterproof seal.
NANCY: Oh, perfect. What a great idea. Thank you so much for your help.
TOM: You’re welcome, Nancy. Good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.