Five Reasons for Chimney Leaks and What to Do About Them

Causes of leaking chimneys can usually be narrowed down to five reasons. If your problem isn’t solved from addressing the items on this list, your leak probably isn’t from the chimney!

common masonry chimney leak fixes

#1 The Simplest Cause of Chimney Leaking: Rain Going Straight In from the Top

Capless Chimney

Capless Chimney (source:

It’s not hard to picture that. Chimneys without covers get a lot of rain falling straight down into them. A chimney cover makes sense to most people. Not only does it keep the rain out, but keeps birds, animals and debris out. The greatest value of the chimney cover is really keeping these out because when chimneys get blocked at the bottom, people get sick (or even die) from CO poisoning. While it’s true that sometimes an uncovered flue is the source of water problems, most often this reason for a leak is only when the liner is metal.

How to fix it

Get a chimney cover and have a professional make sure it’s not this simple.

#2 Many Chimney Leaks are from Cracks in the Chimney Crown

cracked chimney crown

Cracked Chimney Crown

The chimney crown is the cement part on top of the chimney. The bricks go up around the tile flue liners, but at the top you need something to stop the rain and snow from just falling in around the tiles. You can see that the very purpose of the chimney crown is to keep rain out. Cracks in the chimney crown can occur from shifting of the structure or from shrinkage dating back to the first day the crown was put on. When your crown has cracks, the water goes right through those cracks.

How to fix it

How to fix a cracked crown depends upon how bad the damage is. Most crowns have small cracks. Even small ones need to be fixed because all big cracks started out as small ones. Water freezes and thaws in the cracks all winter long, year after year, forcing small cracks to eventually become big cracks. There are excellent crown coating materials such as Chimney Saver Crown Coat which cover the masonry and prevent small cracks from becoming a real problem.

Once chimney crown damage is significant, though, the only fix it is to remove and relay the masonry. You can’t put a band aid on a gushing wound and you can’t coat a structurally ruined chimney crown and expect it to work. Best to coat your crown now with Crown Coat and avoid the big hassle and expense later.

chimney inspectionLeaky Chimney? We can fix that! If you believe that your chimney is causing damage to your home please give us a call or schedule an appointment online. We’ll be happy to help you.

#3 Chimneys Leaking From the Inside Out from Condensation

damage from chimney condensation

Damage from Chimney Condensation

I remember a lady whose wallpaper peeled where the chimney ran through the house. She knew it was the chimney because this is the only place with wallpaper peeling. She had tried everything- a chimney cover, flashing, even rebuilt the entire top of the chimney. By the time I met her she’d spent thousands of dollars but nothing fixed it.

This was an older house with an unlined brick chimney. In 1900 when it was built that chimney carried wood or coal smoke I’m sure. Someplace along the way a gas furnace was installed, but the chimney was not lined with a properly sized liner.

How to fix it

Gas fumes are very low temperature and have a lot of moisture in them. These fumes were condensing on the inside of this too-large, too-cold old chimney, literally soaking the bricks and keeping them moist all the time. All it took was a chimney liner and we solved the problem.

#4 Chimney Flashing Causes Leaks

bad chimney flashing

Chimney Flashing Leaks

TThe flashing is what keeps water from going into the place where the brick structure comes through the roof (or otherwise comes close to the roof.) There’s a fairly large gap between the bricks and the roof and water will pour through that hole if it’s not sealed up. Flashing is often aluminum that goes in between a couple bricks and bends to go on top of the shingles. Some sort of water proof “stuff” seals those spots. Though it’s far from the best choice, the “stuff” is often tar. In any event, flashing doesn’t last forever and the tar lasts even less time.

How to fix it

There are better materials for sealing the flashing now. If you get a chimney sweep to fix your flashing, tell him you want Flash Seal by Saver Systems. (As you can see, I like Saver Systems products; but they just work well, so you can’t go wrong!) It seals better and lasts longer.

#5 Chimney Leaks Caused by Leaking Bricks

leaky bricks

Leaky Bricks; Source:

Bricks and mortar both pass water, and often lots of it. The problem here is the same as with the crown- the freezing and thawing all winter long with the resulting damage which causes leaks in the house.

You have probably heard of waterproofing a chimney, but you have to be careful about what waterproofing material to use. When water is absorbed into a brick or a mortar joint in the summer time, the water probably dries out after a while. The exceptions might be for a surface in the shade or on the side of the house where the sun never shines; those walls just stay wet. That water does try to escape by “falling” i.e. the water weight (or head pressure) carries it toward the ground where it forces its way out of the bricks either inside or outside of the house.

If you apply a waterproofing material that physically blocks the pores of the brick or mortar, the water is trapped inside the brick. Some bricks actually get soggy, though it’s more likely that the water will just seep to the inside of the house. To the point, using silicone based water sealants may trap water and cause more damage than you started with. Use polysiloxane type waterproofing agents, such as Chimney Saver by Saver Systems.

How to fix it

To find out if your chimney leaks through the masonry surface, have your sweep do a Masonry Absorption Test (MAT) This is a simple test where a special test tube is attached to the side of the chimney and you record the time it takes for water to be absorbed into the wall. This tells you if you should waterproof the chimney.

Bonus: #6 Chimney Leaks That Aren’t Chimney Leaks

non chimney leak


Sometimes, a leak starts in a different place but finds its way to the chimney, and then visibly enters the inside of a room at the point of the chimney.

For example, your roof might have a leak through the attic vent or roof shingle at the top.  Water could get into the attic or above your ceiling and either drip to the floor or roll along the stringer (the long piece of wood that spaces out the roof trusses and runs the length of your house). If the stringer is un-level, water can travel a ways – and even wind up at the chimney. It has happened, and usually isn’t discovered until people have spent a terrible sum fixing everything else.

Another event that could happen (although I have never heard of it actually happening) is that you could get so much moisture in your attic that it could condense and roll down the stringer onto your chimney.  This could happen if there were some reason your attic was getting a lot of humidity in it – for example, if your dryer vented into the attic instead of out of a vent perhaps, or if your gas furnace were vented by B Vent but just dumped into the attic (which would be a severe carbon monoxide risk, incidentally).

–Need help with your chimney leak repair in Maryland, DC, or North Virginia? Call High’s!

54 thoughts on "Five Reasons for Chimney Leaks and What to Do About Them"

C. August says:

Great resource! Thanks!

I have a home from 1885 with a very large, unlined chimney (at least 18″ square) that currently serves my oil furnace and gas water heater. I would like to put in a wood stove and was hoping to use some of the space in this oversized chimney for a flexi-steel liner. I have seen conflicting statements about whether I could just add one liner for the stove only, leaving the other two appliances as they are, or whether I need to get a separate liner for each one.

Obviously, I’d like to pay for only one liner, but I don’t want to do it if it’s unsafe. I can’t, however, figure out why I would need three liners.

Any thoughts?


Andrew says:

I am by no means an expert, but I have explored this very issue and from more than one source have been advised that almost all building codes forbid different fuel sources from sharing the same exhaust/chimney. I have no idea if your 18″ square chimney has enough clearance to run 2 separate metal flues/liners for your two/three combustion sources. I am not even sure your gas water heater and oil furnace should share the chimney. My first step would be to check building codes for your location.

Phil says:

My wife and I bought a 20 year old home last year and recently we had a chimney professional out to clean the chimney. While cleaning he indicated that a few things should be done and took some photos of the chimney to illustrate. The damper and grate was rusty so it seemed evident that rain had been getting in – some mortar in the firebox also needed repair due to water damage. In addition, he recommended a new crown (old was cracked) and flue liner. He also recommended a roofer redo the flashing and some overhanging limbs be removed.

We had all of this work done and then we had heavy rains for a few days. At that point I noticed that there was rain leaking into the firebox. It only appears to be leaking down the inside front and dripping onto floor of firebox.

I had the chimney guy come back out and put a new cap on and remove the old damper. I also asked him to look at the flashing that the roofer had done – he said it looked OK. It rained again and we still had the same problem.

So I had the roofer come back out to inspect his own work and also the work of the chimney guy to see if there was anything that looked like a problem. He indicated that everything looked fine.

It rained again last night and of course it is still leaking. So now the roofer and the chimney guy stand by their own work and claim that it is something that the other person did or did not do correctly. I don’t want to pay a 3rd person to come out and look at it. I just want it fixed.

By process of elimination I would like to determine what the most likely cause of the problem is so that the correct person fixes it. How likely is bad flashing to cause a leak inside of the firebox? It seems more likely that it is a chimney issue.

This is really frustrating.

emett says:


Cheryl D says:

I was reading your note on your leaking problem and this sounds just like what my husband and I are going thru. Did you ever find out what the problem was and get it fixed? We also have had two different people come and now we need a repair person to fix the damages of leaking in two bedrooms. Please help me if you can. Thanks!



Have got exactly same problem – spent £2000 so far (flashing, rebricking parts etc etc) and still leaks badly.

Did you solve your problem eventually ?

fm roofing says:

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Dale H Howard says:


Can you give me more details? I may be able to help.

Georgina says:

We just got a quote to have water repellent applied to the very thirsty brick of our chimney. It is approximately 200 square feet. The quote says they need to use at least 12 gallons of repellent. It seems outrageous to me, because, when we were going to do this ourselves, every repellent was 100-150 sf/gallon. Does anyone know if it’s even possible to use this much in one coat? Or am I being had here? Thanks in advance!!

Dale Howard says:

Hi Georgina

The 12 gallons sounds like bad arithmetic or a crazy guess. It won’t use that much. So said, the 100-150 figure is what the manufacturers say but it always takes more than that. I usually use 75 for a figure, and if your chimney is “thirsty” it could be more.

I did a little calculation and if your 200 ft2 chimney is really 180 and if your guy used the 150 to divide it comes out to 1.2. He might have missed the decimal and read 12? I don’t know. While you do have to watch out of course, most guys aren’t actually out to get anyone, but fewer and fewer these days seem to be able to do simple arithmetic.

My guess is it’ll use around 3 gallons (2-4 gallons.) If you liked the guy otherwise give him the benefit of doubt, call him to discuss arithmetic, and see if he’d like to re-price it.

Good luck.

Bryany says:

Have you looked at your gutters? Check to see if your gutters run all the way to the brick, and make sure you have flashing of some type diverting water into the gutter from the sides of the chimney. I’ve seen short runs of gutter cause leaks around chimneys. Sometimes it happens right away. But sometimes it takes a while for the water to eat away all the material before the water can actually penetrate living space. If this is a four sided chimney, no where near a gutter, make sure the roof decking is within a 1/4 inch of the brick. Metal will sag over time if the gap is too large from roof decking to the brick.

Hope this helps

Bryan says:

One more thing. Regardless of whether or not it’s a 3 or 4 sided chimney….Does the broad side of the chimney face peak of the roof? You may need to have a cricket or saddle installed to divert all the water hitting the face of the chimney. If that is the case, water is ponding and backing up under the shingles and a cricket or saddle (same thing) will cure your problem.

Ginger Clark says:

I live in West Babylon NY recently after sandy hit my chimney cap fell and my fence fell and I notices from the ground my roof was buckling even some shingles had tore off during the wind on the edges of the house. The adjuster came out and said I had total damage of 3300 approx. Then the chimney guy came gave an estimate of 5700.00 just to fix the chimney said the flue was damaged, when the chimney cap flew off. Is this possible? NOW in an effort to get insurance company to help fix these repairs I have someone else come give an estimate and he says I have no storm damage and it was a gift from the insurance company and to replace my roof its 12,000 including the chimney repairs. I am not able to estimate my damages ,but the part of the roof near the chimney is eroded now and needs to be repairs can someone tell me what to do. I am clue less about chimney etc roofing. most important thing I need to know is if the cap falls off what else can it damage. I haven’t been able to make any repairs as the insurance company only gave me 1100 to fix all of these damages.

Dale Howard says:

As you might guess, being this far away I can’t make that judgement for you. However, I think I can help. There is a company in Smithtown (which is maybe 20 minutes from you?) called Chief Chimney Services, owned by John Pilger. John is a former president of the National Chimney Sweep Guild and a trainer for the Chimney Safety Institute of America. And an honest man. John also does expert witness work when things wind up in court; whatever he says I think you can call the definitive word. Tell them “hi” from High’s.

Good luck; hope it works out for you

Vic Minaudo says:

I had a stainless steel damper cap installed in 2006 and was told that it had a life time guarantee. In 2008 the cord was rusted and I had it replaced. Just last week it that cord rusted out again. The chimney repair person said my chimney was put on after the house was build. Which is not the case. He also said that there was suppose to be flashing around the sides of the chimney along side of the siding. I had it corked along the siding. I had a roofer come bye and he side that I need a metal flashing around chimney where the roof meets it.

My question is who does the cord keep on rusting. Now the chimney rep wants to charge me $350. for a new cap.

Thanks, Vic

Dale Howard says:


Those cables are supposed to be stainless steel. We just buy the whole thing from the manufacturer and assume it’ll be stainless, but apparently that’s not always the case, as you have found and I’m just finding out. Not much a sweep can do since he just gets what he gets in the box, though certainly understand you didn’t plan to play (and pay) with the darned damper cable over and over.

This answer “ain’t right” but it is the direct approach and will get you the right results. I’m thinking of the lobster in The Little Mermaid where he says “If you want something done mon, you’ve got to do it yourself!” and I’m suggesting you take matters into your own hands and locate cable you KNOW is stainless steel; dig around on the internet perhaps. Hopefully you deal with a chimney company that will replace the cable for free. Regardless, you’ll know what’s in there now.

As for the other comments, it’s pretty hard for me to comment on since I don’t actually see it myself. But this may help: ask lots of questions. The reasons for needing new flashing etc. are all understand-able when properly explained. There’s almost always some reasonable rationale for every suggestion. Sometimes you assume you are accomplishing A, while the contractor is trying to address B. Get on the same page and make decisions from there.

Wish I had better answers for you but hope this helps some.

Gail Goodman says:

I found your site to be very helpful in that I knew almost nothing before reading it. I liked that you even mentioned the flash seal by Saver Systems and that tar is not the best way to go. I have a propane furnace and I believe the flashing is leaking. This new furnace was just put in 3 years ago but the company that did it made mistakes. Like putting the furnace in and not leveling it. It was obviously leaning and I finally had to get the owner there who admitted it and they reset it. They tried to take shortcut and even left some of the old parts there and kept the new parts. Relax. I went over to the company headquarters and asked for the new parts that came with my new furnace. They came back and did it right. What I’m getting at is they probably didn’t do the flashing right in the first place.and now when it rains hard I saw water on the floor. Just alittle and from then on I see no water but if it rains hard I smell mold the next day. Then it dries out.I have two guys I’ve used before who take pride in their work and I’ll be calling them! At least now from your post I understand what they will be telling me. Thanks!

Dale Howard says:

Well thanks Gail!

We’re glad the article could help. Good luck with everything.

Sarah says:

We have a leak in our chimney, water streams down the sides and into the fire box and now into the room below. We’ve had two chimney pros come and look at it. One said we should demolish the top half and have it rebuilt because of spalling brick, the other said we should just waterproof it. So I am confused. Is it common practice to rebuild a chimney on a 40 year old house? Can simple waterproofing work if the bricks have cracks? (We’ve had new cap and crown done, plus replaced around a hundred bricks a few years ago, have already spent more than $3000 on this and would like to avoid spending another $6000! On the other hand, we can’t tolerate a leak.) Any wisdom would be much appreciated…!

Dale Howard says:


If the chimney hasn’t been waterproofed, that certainly figures into this. So yes, absolutely waterproof the chimney, but that may not be (probably isn’t) the full solution.

If the crown is good, and you have a good cap, it’s unlikely that the water is coming in from the top. Seal the crown anyway. And make sure the flashing is good. Flashseal over what you presume to be good flashing is insurance; usually over-kill but in your case maybe you need “extra”

An overlooked area is the rake of a chimney, or shoulder. Outside fireplace chimneys can have water leak into the smoke chamber through this non-vertical part of the structure. And especially if the gutters overflow onto it. So be sure the gutters are working right as well.

As to rebuilding: very possibly a good idea. Waterproofing is great as long as the bricks and mortar are all in good shape, but once they aren’t it may not do the trick. My general reaction to waterproofing spalling brick is that it won’t work; maybe it would, but I’d bet real money against it.

So check the gutters and rake if applicable, rebuild the top, seal the crown even though you’ll have a new one, and waterproof everything with a polysiloxane (Chimney Saver or Weathertight vs something that has silicone in it; we don’t recommend Thompson’s for example) Then waterproof again and seal the flashing (again?) It will take several trips to get all that done because you can’t seal the crown or waterproof the chimney while the crown or mortar is still wet.

Good luck, hope you get your problem fixed.

Louise says:

No one seems to be able to figure out our chimney problem, which started a few years ago, after more than 10 years with no problems, following a record downpour. In heavy rain, especially wind-driven, all FOUR SIDES of the chimney INSIDE the house, from the attic roof to the attic floor, become SATURATED with water. Some water SEEPS OUT at the base of the chimney at the attic floor on three sides: the right, left and rear as you face the downward slope of the roof. (The water seeps out where it meets the concrete “footing” that surrounds the base at the attic level.) No water reaches the fireplace two floors below. I have had chimney sweeps, masons, roofers, and chimney builders attempt various fixes. One cut a hole in the side of the chimney in the attic to look inside and was flummoxed when he did not find a significant amount of water; there was a slow steady drip during a rain shower, which he attributed to a failing crown, but new copper cap installed since then should have fixed that. The chimney has been sealed inside and out, has a new copper cap and damper, has been repointed, the flashing checked several times. Neither of my other two identically constructed chimneys (all roughly 20 years old) has this problem. There is no efflorescence visible on the outside. I do not know where to go next in search of a solution. My current contractor who builds chimneys doesn’t know what to do. The problem chimney is brick above the roof, half-length cement block below the roof; it has only 1 flue in a very large chimney, serving one fireplace that is rarely used; the flue is not encased in solid material but occupies an otherwise hollow chamber inside the chimney. I would appreciate any advice.

Dale Howard says:

I put your question to several friends in the business, and below is a conglomeration of what some of them had to say. Because I’m not there I certainly can’t offer more, and what they suggest is really good stuff.

The suggestion that you wrap the chimney in a plastic tarp and then put water up there is good. You’ll find out for sure if it’s a roof or chimney problem. One fellow says “sounds like flashing” and that’s what it sounds like to me too. Might not be of course, but I’d look long and hard at the flashing before pronouncing it not-guilty.

Good luck!

-Did you wrap the chimney in a tarp to make sure it is a chimney issue and not a roof issue?
-That’s how we would start to solve it…Sounds like flashing.
-Or a water test, gentle spray directed toward the roof and flashing for 30 minutes will tell you a lot.
-I have run into this several times, you need to do a water test, one man on the roof with a hose and one man in the attic with good light, start low and work your way across the chimney about 1 foot at a time for about a 30-60 seconds, run the water then move up, let the water flow and when they get water inside, bingo that is your trouble area or below, remember start low and go full side to side 1st then move up, then to the other 3 sides of the chimney the same way and hit the crown and then flow water over the new cap last, again in a systematic manor
-The real issue is the homeowner asking the question probably has not really consulted a real chimney expert, especially one who deals with water issues. Asking a contractor who builds or more than likely hires out masons to build chimneys is a dead end. The guy needs to hire a CSIA certified sweep.. just saying you had a sweep out doesn’t mean anything.
-And I agree, the first thing to do is wrap the chimney in a tarp and wait for a rain. Takes 10 minutes to do and will narrow down the problem.
-A large chimney with a hollow casing is usually problematic due to insufficient masonry mass, which would otherwise absorb and release the water. Less mass equates to quicker saturation, and subsequently, increased flow of water. This isn’t the root problem, but it is a contributing factor. The crown is identified as being suspect. If the cap lid has inadequate overhang, the crown will still be problematic.
-Is there a sufficient drip edge on the casing?
-How do you seal a chimney inside and out? I’m a little confused on the inside sealing.

Ceci says:


Very good article. Thanks.

I am having, have been having a problem with the bricks in the basement by the chimney “falling apart” and effervescence for a few years. The bricks on the other side(outside) not bad. Had a mason come out since some other contractor I had doing something else at my house said the basement problem was due to cracks in the mortar on the chimney which I didn’t think was correct since the cracks were not many and very fine and the bricks problem was a lot. The chimney was repointed about 15 years ago so to me seemed like it was too early for it to need repointing so that also was telling me that something else was the issue. Since I don’t really know anything about such things, I went and had the chimney repointed where the mason felt it was needed in Sept. of this year. Well, then this winter(coldddddddddddd since live in Chicago) noticed ice on top of my chimney cap. Also, noticed big water mark on the cinder block part of my basement wall right under the chimney today. So, I probably have a crack/cracks in my chimney liner, right? The house was built in 1960. The chimney is for venting the gas furnace. I’m asking since I have had very bad luck with contractors not actually getting down to the root of any problem I have had with this house. Reminds me of mechanics(recent car problem) just throwing parts at it which doesn’t fix the problem.

I have emailed and left messages with several contractors who do chimney work to come out. If it is a crack in the liner, how fast do i have to fix this/replace the liner? I really would like to have at least two contractors come out to see what they say. I have a carbon monoxide alarm.

Sorry for the long post, but… .

Dale Howard says:

I believe this is more straightforward than you might think. It’s a pretty classic case of condensation in the chimney, and freezing where the water forms. I have seen gas-venting chimneys completely close off because of the ice. What happens is that the moisture in the flue gasses, and there’s quite a lot of it, condenses. The chimney is so cold that it not only condenses, but also freezes. That’s what’s going on with the big wet spot. If you have that same big wet spot when it stays above freezing for a long time, then I am wrong. But experience tells me I’m probably right.

You may or may have cracks in the tile, and I hear you about having the deterioration problem inside but not outside, yet that’s not really the issue to focus on here. The solution to your problem is to have a properly-sized, insulated, round chimney liner installed (usually stainless steel with insulation around it.) Depending on the size required and the size of the existing tiles, those tiles may or may not have to be removed in order to do the job. Just be open to hearing that if it’s the case. And for the record, if your house is tight and/or there’s a strong stack effect in the house, you could still get back-flow; a different problem. But the chimney liner with enough insulation should solve the problem you describe.

Stay warm!

Ceci says:

Sorry, meant ice on top of my chimney crown, not on the metal cap. All these words are new to me so get mixed up sometimes.

Josh says:

I’m not sure maybe some one can help here. I had a new chimney built through the middle of my house last year it is block through the house and brick though the roof. Have had the installer come back atleast 5 times and it still leaks. It leaks through the roof line and in the 2nd story bad room the blocks get wet at the mortar joints from the inside out and the water moves its way down down the joints. It seams to do this when it really windy and raining. Could flashing do this, water seeping through the brick? I can’t figure it out any help would be great!

Dale Howard says:

Not being there I don’t know this for sure of course, but since you mention the problem is wind and rain related, here’s what I suggest:

First, give up on the installer. It sounds like he’s a good man since he came back five times, but he doesn’t seem to have answers. Bring in somebody who advertises that they fix chimney leaks if you can find one.

And here’s where I guess the problem will turn up. I think if you put on a chimney cover with a big enough lid to keep rain out even in the wind, seal the flashing, seal the crown and waterproof the chimney you will probably fix the problem. Now you may have a roofing problem as well or instead, but there’s a good chance that if you do these things you’ll nail the problem.

Good luck, stay warm!

Prashant says:

Well, can anyone guide me out here, I have a different problem alltogather, I run an industry, and my chimney is 40 ft tall, my neighbor complains of falling carbon particle in his premise,
He wants me to increase the height by another 20ft, the cost is almost 6000 $’ can I have a cheaper option. Also I don’t have a cap on chimney, will it help in anyway, If I put a cap to existing chimney. Hope to look for an appropriate answer. Thanks prashant, 0091-9819875859. Thanks

High's Chimney says:


I have to wonder if 20 feet of chimney is the answer. I think you will do well to have the boiler mechanic come out and make sure the burner is running properly. This sounds to me more like an incomplete combustion problem.

You will want to have the chimney cleaned *real well* to get the existing soot out, and if you have visible particles escaping I’d bet there is a lot of soot built up inside the flue. Also, be sure the chimney is sized properly to the appliance; one of the reasons a chimney gets dirty can be related to wrong sizing (which can provide insufficient draw) But you almost certainly have some problem at the burner.

Don’t buy 20 more feet of chimney just because your neighbor thinks it’s a good idea. Do get a cap, but I say that on general principles- it won’t solve this problem.

Good luck

Lisa says:

I recently bought an 80 year old cabin, 400 s.f., heated by a Frontiersman woodstove. Several times I have arrived to find a small puddle of water under one of the feet of the stove, and thought I’d left the flue open and water had flowed in. This weekend it was pouring rain, and water was flowing down one half of the “front” of the brick chimney inside the house, and down the corresponding side. After the rain stopped and the brick dried, it began to rain again and I was able to see that water was flowing in between rows of bricks in a few spots. Before I have carpet installed, I need to stop the leak, but don’t know what to do. The seller had coated the chimney from the roof about halfway up to the top with some sort of silver colored material. The roof is metal, which means it is too slippery to climb around on in the rain, and it is ALWAYS raining! It seems like there may be some mortar missing from the part of the chimney above the roofline on the side where the leak originates, as the area where there should be mortar appears to be recessed slightly and dark in color. Do I need to have the chimney removed and rebuilt? Or is it possible to “fill in” the missing mortar and then waterproof the chimney from the outside? I have photos of both the inside with varying degrees of leaking, and the outside, taken from the ground in clear weather if that helps.

High's Chimney says:


You have the advantage of knowing it’s a rain related problem. And you have seen it coming in through mortar joints.

The silver stuff on the chimney I imagine to be metal roof paint. It’s fairly common to see the flashing painted further up the chimney.

My guess? You may well need “the works.” I think you’d be wise to have bad mortar joints fixed, the crown sealed, a chimney cover to keep rain out of the flue, waterproofing on exterior bricks and a properly sized liner. None of that work will be hard to get done, so get a few prices, but choose the person who impresses you as most knowledgeable and competent. Lot’s of incompetents out there who will gladly take money without fixing the problem.

Bottom line is I don’t think it’s going to be hard to stop that leak, but it’s going to cost some money, that’s all. And, if you’re fortunate, that knowledgeable competent person may see something that will preclude “the works” and you’ll save money! If I had a cabin I would go ahead and treat it to the works anyway. All those items are good things to do anyway.

Good luck with it.

Richard Pelosi says:


Great article I think it has helped me solve a three year problem. Our house is about 90 years old and in 2010-11 we did a major renovation including a new central heating and air-condition system. About 4 months after we moved back in we noticed water damage along the wall where the chimney is directly outside on the top floor and the top of the first floor. We rebuild he top of the of the chimney with a new crown, new cover and new flashing also a new roof was done during the renovation. Last year they tried two coats of a sealant on the outside of the chimney and after repairing the walls about 5 months later the wall started to bubble again. With the last idea of rebuilding the entire chimney i saw you article and called a chimney specialist and he immediately said it needs a new liner. He took off the tubing from the furnace to the chimney and said that was moisture causing the problem, and if it was coming from the outside you would see water running down the walls not bubbling. I thought of the lady withe pealing wall paper in reason number #3. He said he was 95% sure this is the problem, I just wanted your thoughts before I spent $2,200 on a new liner. Also my heating guy did say that the new system sends exhaust from the furnace at a lower temperature and maybe causing more moisture.

High's Chimney says:


Sounds pretty classic to me. Not being there I can only make my best guess of course, but sounds right to me- it’s an inside problem. As I say, sounds classic so I think you can proceed with a high degree of confidence.

Glad you’re finally getting the problem solved.

Lesley Landis says:

Our chimney is currently leaking water. We had a problem quite some time ago when we had a heavy downpour. Since getting a new roof this summer we had no issues until now. We have had lots and lots of snow this winter. Now that we are starting to thaw, you can hear a constant drip in the firebox and noticeably damp inside. Just moments ago a small stream started to pour every few minutes. I’ve put a bowl in the box to collect water and I see nothing other than some soot in the water. This stream is towards the front of the box. Due to all the snow and ice it isn’t possible to get on the roof to look at the chimney ourselves right now. Any ideas?

High's Chimney says:

Snow stays a long time and thaws slowly. Keeps a chimney wet. My guess is it’s going to be either the flashing, crown or shoulder of the fireplace.

As you know, my belief is your best bet with leaks is “give ’em the works” i.e. cap, crown, flashing and waterproofing. Unless a roof inspection yields something obviously wrong (flashing perhaps) I think your best bet is to wait until it gets warmer and the structure dries out reasonably well, and then waterproof it etc. (“the works”) Be sure your installer pays particular to non-vertical areas such as the shoulder around the smoke chamber.

It would be smart to look up in the attic too. If you see evidence of water running along the stringer from somewhere else, then of course you have a different problem. So said, if the roof is new seven years ago and no problems since then, it’s probably got to do with the chimney.

Good luck!

frank says:

have new house 1 1/2yrs old, have an exterior chimney that is in used for a gas fireplace on the second floor…water is leaking into the first floor foyer ceiling and wall just behind where the chimney is located on the exterior…any thoughts on likely problem?

High's Chimney says:

Just noticed I missed answering your question; you have probably discovered the answer by now. Sorry about that…

Sounds very much like condensation leaking out of the system in the chase. It shouldn’t be so cold in there you have that kind of condensation, and the vent should be well enough sealed that the water shouldn’t get outside the system.

Something is real wrong in the chase. I suspect there will be both a problem with freezing air blowing through the chase and disconnected/misaligned/missing/whatever pipes so they don’t contain the products of combustion. It is reasonable to wonder if you have CO in the house as well.

Do get someone in to examine that chase and the integrity of the chimney vent.

Good luck!

Anthony says:

My brick home is only 6 years old in a suburb outside of Chicago. As you know, we’ve had a very bad snowy and freezing winter for the past 2 months.
I have a wood burning fireplace in the northwest corner of my home on the first floor. My foundation bumps out to the west in that corner to accommodate the face brick on the exterior of the chimney. There is a cinder block wall that starts on the basement floor and goes all the way up the exterior of my home above grade to support the east side of the brick chimney above the roof.
After the heavy rain last weekend after 2 days of thawing, I discovered water just inside that block wall in my basement. The water was dripping off of the tyvek house wrap that runs all the way up the frame of my house that the block wall is up against. That tyvek wraps under the toe plate that sits on the top of my foundation walls above grade. And the drops were coming off that wrap right in the middle of that 2 foot wide cinder block wall at the ceiling of my soon to be finished basement. I’ve never noticed any water there before..and no seepage anywhere along my foundation walls.
There is no sign of any water anywhere else in that corner: the inside of the firebox is dry. The wall and ceiling in the corner on the second floor show no water spots. And the attic is too dark in that corner to notice any water (difficult to get to since it is the lowest part of the attic ceiling.
I assumed immediately it was a flashing problem and water is simply running all the way down my house wrap in between the wrap and the block wall (a long way to travel, but still…). However, after reading the comments here about chimney condensation and brick/mortar sealants, I am second guessing. Any comments? – sorry I was a little long-winded.

High's Chimney says:


Since you never had a problem until a heavy rain, my best guess is that it’s rain-related. And once something is soaked, it can slowly feed water to other places (drip of other masonry, run along a rafter, find it’s way down the tyvek etc.)

The details might be interesting, but they are academic for sure. You might want to just say “OK, how can water get in anywhere?” and it’s the usual suspects 99% of the time. Flashing, caulking, otherwise sealing and waterproofing (and always a chimney cap- don’t forget the obvious!) is likely to deal with your leak. As I like to say, give it the works.

See if that doesn’t help. You can look for exotic causes later on if doesn’t, but the combination of sealing the crown, flashing, caulking, capping and waterproofing the masonry almost always nails it.

Good luck!

Carl Patenaude says:

How does water end up at the base of the chimney leaving a one foot wide path to the bottom edge of the roof? Keep in mind this chimney and roof shingles have been inspected and flashing is sealed.After 2 chimney contractors did minor repairs we are still getting water leak in the bedroom approx. 1 ft. away from the chimney the ceiling is laticed/sheetrocked .There is no snow on the roof and all water is dried.Can’t figure out for the life of me where the water is coming from.Its been so cold here in Massachusettes that the sream of water on the roof freezes at nightfall. thank you.

High's Chimney says:


Since you have a water problem when the roof is dry, my first guess is condensation from the flue gasses. If it’s not that then one would have to guess something very unusual. Water line passing through the attic or something. Condensation doesn’t usually display itself in this fashion- a stream of water.

Sorry to be useless here; this really is interesting and I’d love to hear what it is when you find out. If it’s chimney related I’ll be happy to learn something new.

Hope you get it, good luck.

Barbara says:

I have a strange orangish sort of waxy or oily stuff dripping around the outside of my furnace chimney into my basement. Do you have any idea what it could be?
My house is from the 1920’s, and a new roof was put on about 7 years ago. I’ve lived there since 1987 and have never seen this. The furnace is gas. I live in north-central Ohio and this has been the coldest winter I can remember. When I first discovered the leaking into my basement I went to the attic and found that it seems to be coming from the roof, and the substance is running all the way down to the basement, and on all four sides of the chimney.
I looked online (which is how I found your site) but I’m not finding where such a thing is addressed anywhere. I don’t know who to call about it since I don’t know what it is. Would it be related to the relatively new roof – so should I call them because the roof is under warrantee? Is the substance dangerous?
Please help if you can!
Thank you!

High's Chimney says:

This is an interesting one.

Offhand I’d say it *could* be the roof, but the roof isn’t new and this is the first year with the problem. What is different is how-cold-how-long it’s been this year.

When you refer to your furnace chimney, I assume it’s a masonry chimney (you mention all four sides) If your fuel were oil this would make more sense because the dye in fuel oil often runs on the outside of chimneys in the condensate that forms at the chimney cover. If this is strictly gas I don’t know why orange stuff should run, unless it’s rust from a non-stainless steel chimney cover. Which wouldn’t be oily…

If in fact you have B Vent, here’s a possible scenario. Maybe the gas exhaust is condensing in the flue (very possible indeed) and you have water running down inside. That moisture has hydrochloric acid in it so may have eaten the aluminum in side the B vent (not uncommon.) At which point it can start eating the galvanized outer layer too. And then you could see orange stuff (rust) running down the outside of the pipe. That doesn’t explain why it should be oily either.

Since there is no fast and obvious answer here, my best advice is to bring in a certified professional who’s been in business for a lot of years (experienced only!) to look it over. And if you find out what it is, I hope you’ll come back to the blog and tell us. This really is interesting.

Good luck!

Ann Lints says:

I don’t see water to confirm that my chimney is leaking but during the winter, even when I remove all the ashes, our home smells like wet ashes. I close the damper but still have the strong smell. I do see some streaks of white on the outside of the chimney. Does that mean moisture is getting thru the bricks? My home is a fairly well built 20 year old house. Do you think that sealing the exterior would be the best first step? Any advice would be helpful.
Thanks very much!

Bill Luster says:

I have water coming in my chimney directly inside my clay chimney flue.
The chimney has never been used and I have completely sealed the top of the flue with a metal cover. I keep a bucket below the flue to catch all the water which is coming from inside the clay flue. It has been this way for years. Can’t seem to figure it out.
Help please

High's Chimney Service Inc. says:

The info here makes me think that this is NOT rain related; you don’t reference rain at all. If it is rain related though, do the obvious; put on a cap and make sure the crown and flashing are good. Also, some bricks can store a lot of water so waterproof when you know the structure is dry.

Assuming it’s not a rain problem, and you say this is an unused flue… that’s pretty interesting. Since “it doesn’t make sense” you will be looking for things that you’d assume are OK but surprise! something won’t be OK. It can be crazy stuff. Don’t rule out things like a pipe leaking in the attic.

Given that you will be hunting for odd stuff, I’d start with making sure that the unused chimney is actually unused. Seriously; it would not be the first time a gas flue was supposed to be running somewhere else but it was going up a blocked off flue instead. Venting gas into a blocked flue will create a small river of water.

Good luck with it; let us know what you find out please.

Bill Luster says:

Sorry I should of specified that it only leaks when it rains. I have put a cap on (completely sealed the top). does not leak during very light rain. It also seems to leak more if the wind is coming from the east and the chimney is on the east side of the house. The water is definitely from the inside of the flue. It goes down the flue to the basement into a rough in space for a fireplace, which was never built. So rain must be getting thought the bricks but I don’t understand how it can get into the clay flue if it is sealed at the top.

High's Chimney Service Inc. says:

Since this is rain-related, and you have the top sealed off, then you make sure the other points of entry are covered.

Seal the crown. Or you can replace if it has large cracks. Make sure the crown is tight first of all. We have an article on crown repair: /articles/all-about-chimney-crowns/

Waterproof the chimney (Use a sealant like Chimney Saver or WaterTight. Don’t use a silicone-based sealer.) I suspect waterproofing will do the trick.
Repair (repoint or rebuild) if appropriate. More on that here: /articles/this-old-chimney-part-1/

Repair or replace the flashing as appropriate. This article talks about problems with flashing: /articles/how-can-you-tell-if-your-chimney-or-fireplace-needs-a-repair/

Less frequently a problem, but still check for it: rain enters through the roof somehow and makes it’s way into the chimney.

This should get you fixed up- good luck!

Sondra K. Prine says:

I bought an older home in 2012 with two chimneys’. I noticed some old water damage but assumed the cause had been fixed. No info becaUSe this was a repo, bank owned home. Early this spring,. I noticed some of the same activity on one of the chimney’s. Paint was pealing on the second floor with nothing else visible until the basement…where, close to the ash removal door and about 3 1/2 ft up from the basement floor, water is shown to have suddenly leaked out of the bricks, run down and puddled on the floor. I might mention I had the chimney’s sealed last year. Just last week, I had an entire new roof put on. When it rained the next day, and leaked, I called the roofing company and they sent a man out to check and he resealed everything around the chimney. Today, another big storm and the chimney is still leaking. Monday, I am going to replace the rain cap on the leaking chimney. If this doesn’t work, I don’t know what to do next. Do you have any ideas? I’m 72 and cannot get on the roof myself to look and so must depend on what I’m told. I have been told that the rain caps are fine however, I’m thinking they must not be looking at it close enough. The offending chimney is near the peak of the roof and no where near a valley. I would appreciate hearing from you. I live in Waverly, Illinois.

Arthur McGrew says:

I have a hundred year old house that I bought 8 years ago that did have the furnace vented into the chimney. after a few months into the house I noticed that the wallpaper just above the mantle was bubbling and wet but there was no moisture on the ceiling. when I ask the previos owner if he had this problem before he said no but he did say he had just put a new roof on four moths before he sold it. I had the plaster wall repaired and had a roofer and chimney guy out who both said the flashing looks fine. I added a cap to the chimney and replaced the old spalled brick from the roof line up. I replaced the furnace and now am not venting into the chimney. However when it rains heavy, days later the wall area about 2 feet high ifrom the mantle up is dripping wet through the plaster. It also seems worse if I am not running the air conditioning. Do I need a new liner or should I just seal the brick? Can I seal it if it is painted?

Mary Bottoms says:

I have a house that is 40 years old. The chimney has bad Spalding. We have put in a gas vent free insert and no longer ust the chimney. It goes through the edge of the overhang. What do you think of the idea of taking the chimney down to the roof line and capping it off.

Becky says:

We fixed crown, repointed, and did Chimney saver flashing with new Chimney sweeps.

The Mason before this one applied “syloxane” as a waterproofer. Is this the bad stuff then?

Can we apply good waterproofer over bad? What can we do to fix?

(We get water “pushing down” the bricks. After watervproofing treatment above, it slowed down some, but didn’t stop.)

High's Chimney Service Inc. says:

No, siloxane is the good stuff. Unless there is some other point or
entry you haven’t figured out yet, it might be as simple as putting on a
second application. For most people one time is sufficient, but if the
surface is more porous or if not enough material is applied the first
time, a second application is in order. Give that a shot.

Whoever you get, tell them to be liberal with the material. Squirt down
that wall until it won’t soak up anymore!

Sounds like you’re getting it; good luck!

Emily says:

My two-story house was built in the 1930s and my boiler now vents out of the brick chimney. I renovated the main floor and put all new dry wall up. There are absolutely no signs of leakage on the main floor. However, on the second floor, nearing where the chimney vents out of the roof (I have a very high pitched roof) there are a tremendous amount of water marks on the walls and ceiling surrounding the chimney. I have had several people come out and try to remedy this problem for me. I’ve even had the old plaster torn down, and new drywall put up. Roofer says flashing looks fine and that there are no leaks he can see in the attic, new liner in the chimney has been installed. I’ve thought condensation was the problem, but how can one explain the fact that the chimney has no issues on the main floor, and only on the second floor… What are some other options that can explain this moisture in my walls around the chimney?

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