Help! How can I fix my leaky chimney?
November 3, 2014 3:15 PM   Subscribe

During rainstorms, water runs inside my house, down the front of the chimney. I climbed up on the roof and took some pictures of the top of the chimney - it looks like the cause of the leak is the coating of black material covering the top. It is cracked and peeling in many spots. See picture 1, picture 2, and picture 3.

Is there an easy DIY remedy to this problem, or do I need to hire someone? If the later, who would handle this kind of a problem? A basic roofer? Thanks!
posted by steinwald to Home & Garden (11 answers total) 2 users marked this as a favorite
I would hire someone. You might need a roofer and a mason. Water is the #1 enemy of a sound house so please don't delay.
posted by killy willy at 3:22 PM on November 3, 2014 [1 favorite]

Leaks rarely come from where you think they are coming from. Water is sneaky. I would hire someone (a respected roofer) to trace it for you.
posted by cecic at 3:23 PM on November 3, 2014 [2 favorites]

Chimneys usually have flashing, a metal strip which bridges the gap between roof and chimney, extending for several inches under the shingles and up onto the sides of the chimney, and is generally tarred in place.

I can't be sure, but it doesn't look to me as if your chimney has this, and if so I'd say it needs it, and I think that would be a job for a professional.
posted by jamjam at 3:56 PM on November 3, 2014 [2 favorites]

I agree, bring in a roofer. And, as jamjam said, it's the flashing that seals between the chimney and the roof. If water is running down the front of the chimney, I suspect that is where the problem is.
posted by HuronBob at 4:14 PM on November 3, 2014

Best answer: You need to hire a licensed and bonded roofer to inspect your chimney and roof, and another contractor to inspect for water damage inside your home itself.

The black stuff looks like tar or roofing cement, and while both are often used as a permanent "patch" solution around chimneys, they're meant to be temporary. A roofer will inspect your chimney for the following things: various needed flashing types like step flashing on the flat part of the roof which is bent in the the middle to go up the side of the chimney; a bead of roofing cement where the shingles meet the flashing (although it doesn't look like you have shingles); loose or missing mortar in the bricks; necessary flashing around the vent itself (you can buy vent flashing); the roofing solution if it is tar or asphalt; necessary underlayment such as roofing felt; if a chimney cricket is necessary; and drainage.

The other contractor will check for structural damage from moisture intrusion to rafters and walls, and can pinpoint if water is coming from elsewhere than the chimney, as water often gets pulled along the edge of rafters for a distance before falling. They can check for mold as well, and will have a moisture meter to check for moisture in wood and drywall.

This does not sound like a DIY situation for you. However, be of some hope: Inadequate or deteriorated flashing is the main cause of chimney leaks, and is relatively inexpensive; and if water has just run down your chimney then structural damage may be minimal or non-existent.
posted by barchan at 4:25 PM on November 3, 2014 [1 favorite]

Chiming in to agree with above and also site masonry problems as a possible source of the water. Your chimney may need to be repointed (updating the mortar around your bricks) for better moisture management
posted by Suffocating Kitty at 4:45 PM on November 3, 2014

posted by meindee at 5:21 PM on November 3, 2014

Look at the *base* of the chimney where it meets the roof.
Might also use the "Find a Member" function on the r/h side of the screen at
posted by rudd135 at 7:27 PM on November 3, 2014

Best answer: The ideal solution is as barchan said. Although:

The black stuff looks like tar or roofing cement, and while both are often used as a permanent "patch" solution around chimneys, they're meant to be temporary.

It's basically like an asphalt driveway. You need to re-seal it every few years. The thing is, adding flashing when you have a roof in place can be a tricky ordeal that introduces the possibility of new leaks, so it might be best done when you put on a new roof. (The house I'm in, my dad did not have the chimneys flashed when it got re-roofed about ten years ago and so I have to climb up every 3-5 years and slather on a little more tar. It's quick, it's dirty, and it isn't permanent, but it can do the job for a while until you want to re-roof the whole place. I'm not advising you to do this, it's sub-optimal, but it's quite possible that it could get you through.) I also believe that flashing may not be your problem here in that there are obvious cracks and deterioration on that top layer of tar.

Something else I'll bring up here is that the masonry chimney itself is very large compared to your flue. This may mean that it originally carried multiple flues, perhaps for different fireplaces/stoves, depending on the age and structure of your building. But at some point that heating was replaced by a central boiler/furnace, which only needed the single flue. (Although it looks like you're in a ranch house suburbia and this is a lannon-stone type chimney for what may have once been a big sixties fireplace -- but fireplaces are typically negative in terms of energy efficiency, so they reduced its size/exhaust requirements. Or ... maybe it was just aesthetics, but personally, I feel like the roofing tar is a kludge.) As a result they covered over the unused flues with this "roof" of tar which is ginormous and basically a huge leak waiting to happen.

I would bring up with your contractor what options he suggests for what is effectively a mini flat roof, which unless you layer them properly are maintenance-intensive. What you need is probably a chimney crown or something with a similar name/function. This might be metal or masonry and will have enough slope to it that moisture does not pool. (My own chimney's crown is concrete, or whatever variant of masonry cement is used in these applications.) [1] [2] [3] There are also flue cap systems that have an integrated crown and cap. [4] One of these would be best for a long-term repair. Even though metal can oxidize and concrete can crack, since chimney tops are subjected to severe weather, they will last longer than a re-tar.
posted by dhartung at 11:06 PM on November 3, 2014

Best answer: I've been on upwards of seventeen hundred thousand roofs, seeking out water leaks, flashing chimneys, fixing leaks, on and on.

I'm here, and not on the roof with you. From my seat in the house, I'd say first thing is to take the aluminum chimney top etc off of the entire, have a tray made out of fairly light gauge sheet metal, with a 3 to 4 inch lip turned down. Any sheet metal shop can make it for you, probably install it, too, if you want. You'll never have to worry about the tar jive again, not on the top anyways.

I'd look also for other obvious problems. But I know what I'm looking for. You might want to hire someone to help you; if you were in Austin we'd get up there and take a peek, you'd just have to buy me a coffee or some such.

As noted upthread, water *is* weird -- you end up with water coming in over here but the leak is way across on the other side of the roof, it follows a joist or a piece of conduit or god alone knows what else, it's a total PITA to troubleshoot them.

Start with a cap on the top, look for anything else obvious, then wait for rain, see what happens.

Good luck.
posted by dancestoblue at 1:35 AM on November 4, 2014 [1 favorite]

Response by poster: Thanks for all the responses. The roof is a new rubber membrane roof, installed last year. New flashing was installed at the base of the chimney at that time. For those reasons, I strongly suspect the water intrusion is coming from the top of the chimney. The chimney crown or cap seems like the best solution.
posted by steinwald at 4:06 AM on November 4, 2014

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