Chimney Leaking Water
LESLIE: Next up we have Tim from Knoxville, Tennessee whose chimney is having some issues.
Tim, tell us about it.
TIM: What’s been happening, for some reason there’s liquid – what I assume is water-based liquid; it’s bleeding through the mortar. And I’ve tried to paint it with a concrete sealer and I’ve have it swept, I’ve had some mortar repairs done on it but it continues to bleed and what happens is it bleeds onto a patio and pools up there.
TOM: And this is on the outside of your house?
TIM: Yes sir, it is.
TOM: And so, basically, this masonry structure is soaking up with water and then it’s leaking out below.
TIM: That is correct.
TOM: Have you gone up on the top of the chimney and checked the chimney cap? Now that’s the masonry lip between the outside of the brick edge and the flue liner.
TIM: There was, at one time, no cap at all and I installed one.
TOM: Well, I think what’s happening here is masonry in general is very hydroscopic and what that means is it soaks up a lot of water and can hold a lot of water. It is possible that the water that you’re seeing in there could be actually pulling up from the ground as much as it’s possible that it’s coming down from rainwater from above. But in either case, sealing that masonry is about the only thing that you can do. You can cut back on the volume of water that it’s getting there. Now I don’t know what the drainage issues are right around there but if it’s possible that there’s water ponding at the bottom of that chimney during rainstorms, that could be actually pulling it up.
TIM: The chimney does come around a covered patio, so there’s not a whole lot of water pooling unless it’s coming from under the patio.
TOM: Right, and that’s entirely possible. Unfortunately, the masonry paint – which is probably not the best thing to put on there; there are masonry sealers that are clear …
LESLIE: It’s a polyurethane/concrete mixture.
TOM: Right. And that one actually is vapor-permeable which is important because as that water is trapped beneath that pain surface it’s held into the brick and through the freeze-thaw cycle you will actually expand that brick and potentially break pieces off. It’s a condition called spawling. So that probably wasn’t the best thing to do. So now you’re looking at a chimney that’s painted; you’re wondering what the heck you should do about it.
My advice would be to first look for sources of water that could be getting under that patio and contributing to that. Second, reexamine the chimney cap at top. And when I say cap I don’t mean the physical metal cap; I mean that brick – that masonry, concrete lip between the outside of the brick and the inside of the flue liner to see if you’re stopping water from getting in there above.
TIM: Part of the area that I did make the repair several months ago, so I may be still dealing with residual water that could have gotten in through there.
TOM: Or is continuing to get in. Did you repair it with caulk?
TIM: No, I repaired it with a premixed concrete.
TOM: Well, check that to make sure it’s not shrunk and pulled away because sometimes that will happen.
TIM: And so if nothing else, am I left with just a sleeve I may have to put in or something? Is there anything if none of these additives …?
TOM: Well, I think that the idea of a chimney getting wet and then water draining out of it is actually a fairly normal condition. In your case, it happens to be on the patio, so perhaps it’s more obvious. But if that patio wasn’t there, that would be running right back down to the ground. The last tip I’ll give you is this: if it really, really bothers you, cut out the patio right around the bottom of the chimney.
TIM: Well, I appreciate your taking my call and that’s a lot of good ideas. I’m just desperate to get it done.
TOM: Alright, Tim. Thanks so much for calling us at 1-888-MONEY-PIT.