Leaking Fireplace: Causes and Fixes
LESLIE: Now we’ve got Dina in New Jersey on the line who’s dealing with something going on with the chimney. What’s happening? You’ve got grout crumbling? What’s going on there?
DINA: I have water, apparently, leaking in and it’s coming down around the fancy bricks of my fireplace. Because I see the cement crumbling and I see changes of – after a rain that I have, it’s darker over on the cement that’s crumbling.
I’ve had my chimney relined and I just don’t know what it is. They said maybe it’s the flashing up on top that needs to be repointed and then it should be sealed. I just don’t know where to start and I’m getting high, big prices.
TOM: Alright, Dina. This is a masonry chimney?
TOM: A brick chimney, yes. OK. Masonry chimney, OK. Same difference.
DINA: OK, thank you for being there for people like me.
TOM: Alright. “No, it’s not masonry, it’s brick.” “Well, that clears it up.”
Alright, look, when you have a masonry/brick chimney, at the top there is a chimney cap, which is a concrete lip that goes between the flue liner and the outside of the brick edge. And typically, when you get leaks, that concrete cap is cracked. And it’s a very minor repair to seal those chimney cap cracks or even to replace those cracks – that concrete section. It’s just a little, maybe 6-inch-deep section of concrete that’s sort of troweled between the clay flue liner and the outside edge of the brick.
So the first thing I would do is seal the gaps or cracks around that and see if that fixes it. Now, the leaks are coming into the chimney. They’re not coming around the chimney by the ceiling, right? So that means – that sort of excludes flashing, because the flashing seals the gap between the masonry chimney and the roof. And if the flashing was failed, then you would have, probably, leaks when you look up at your ceiling. The chimney itself is leaking, so the most common culprit is simply that concrete cap or that masonry cap around the top of it.
The other thing that you could do is you could put a chimney cap on this, because that has the effect of sort of putting a roof over your chimney without really blocking the chimney. And sometimes, that will dissuade the volume of water from getting into it.
Now, the – one of the things I have to caution you about is that the chimney sweeps – the chimney contractors can be a disingenuous group. They’re not the most honest contractors out there and they almost always try to tell you a tale of woe, of death and destruction that will befall upon you unless you open your checkbook open wide and write them a big number. So, just be careful to find somebody reputable that can dig into what’s going on and just do what’s necessary but not an excessive amount of work on it, OK?
DINA: Uh-huh. They’ve also mentioned doing repointing on the chimney and then waterproofing it.
TOM: If it turns out that the masonry is cracked or deteriorated or falling out between the bricks, certainly repointing – but I think it’s a lot simpler than that. I think most likely it’s just some minor cracks in the chimney cap.
DINA: Uh-huh. Because what they showed me was – they said, “See? There’s moss growing here. So that means that there’s water in between the bricks.”
TOM: There’s always going to be water in a chimney. It’s a masonry structure; it holds moisture. And if you’ve got moss, you can put a mildewcide on it. You can put a product like Concrobium on there that will kill that moss or another product called Wet & Forget that will kill that moss. And then beyond that, you need to get to the source of the leak, which I think is that chimney cap.
So let’s not overcomplicate it, OK? Let’s see if that thin concrete cap is cracked and get that fixed.
DINA: Thank you so very much. And now I know that bricks are masonry. Thank you.