How Can I Fill a Space Between My Patio and Patio Door?

LESLIE: Jim in Washington, you’ve got The Money Pit. What can we do for you today?

JIM: I’ve got a rear patio that’s an aggregate cement. And there’s a gap between the edge of that that goes under our rear sliding-glass door, under the threshold. It’s a gap of about 3-4 inches and about maybe a foot or 2 in length. What can I use to kind of fill that void so we don’t get like rain in there and insects or even rodents?

TOM: So, you have space between the patio and the actual patio door? Like it didn’t press up against the house kind of a thing?

JIM: Correct.

TOM: You said it’s about 3 or 4 inches deep?

JIM: Yeah. The gap is, yes.

TOM: The gap is. And you said it was a foot-and-a-half wide. You threw me on that because it sounded like it’s not going along the entire length of the door?

JIM: Yeah, correct. It’s just about maybe a third of it.

TOM: So we need to figure out a way to kind of fill this in and perhaps make it blend in with the patio. What I probably would do here is – can you dig this out and make it a little bit deeper so we can get a bit more concrete in there?

JIM: I could do that. It’s aggregate, though, so I’m not sure how well it’s match.

TOM: Because I’m afraid if you put something in that’s not very thick, it may crack and break up very easily. But if you were to dig that out a little bit, put a little stone in the bottom of the pit and then use an epoxy patching compound and mix the concrete up with the epoxy products, then you’re going to have something that’s going to be less resistant to cracking and more likely to stick to the old patio.

Now, in terms of coloring it, you’re probably going to have to use some concrete dyes. And they come in different colors but you may be able to dye it to get somewhat close to what you have there now.

JIM: OK. It’s aggregate, so how do I deal with that?

TOM: So it has sort of a stone – has like a stone-like finish on top?

JIM: Yes.

TOM: Well, could you add aggregate to the top of the concrete mix?

JIM: Yeah, I could try that.

TOM: So there’s another way to do it. This way, you’ll have the texture and the color, as well.

JIM: Yeah, OK. Sounds good.

TOM: Just do it all at once and let it set. But use the epoxy patching compound, which is kind of like a concrete mix except that it’s very sticky.

JIM: Mm-hmm. How much do I need to cut out? How much should I fill?

TOM: I mean if the depth of that replacement section was 3 inches, that should be plenty.

JIM: OK. Sounds good. Well, thanks for your help.

TOM: Alright. Good luck with that project, Jim.