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ChimneyNovice 12-25-2012 05:36 PM

Chimney mortar smell makes you feel sick
Hi - I'm trying to solve an odd problem with a brick chimney. I've lived in this house for more than 25 years. But only recently I've noticed that some of the lines of mortar between 5-6 rows of bricks on 2 sides of the chimney, about 4 feet below the ceiling, look and feel damp. The damp areas vary from 6-12 inches long. The chimney goes through the attic, so these damp areas are about 8-9 feet below the level of the roof, and about 13-14 feet below the top of the chimney.

The problem is that these damp areas have begun to give off a strong odor of perfume! You can smell it from 10 feet away. Both my wife and I smell the same sweet smell, like a cheap perfume in a detergent. The smell is so bad it makes me feel sick and cough.

The mortar that looks and feels slightly damp is darker than the surrounding mortar (which doesn't smell). We assume, but don't know, that the smell is due to mold. There isn't any fuzzy mold growth on the surface of the mortar, and brushing pure bleach on these areas doesn't stop the smell, nor does using X-14 mold and mildew killer.

So I have 2 questions: How to get rid of this sickening smell, and what to do to stop the mortar from getting wet.

We live in the NW, so get a lot of rain. The chimney has a metal chimney cap (the kind that rotates in the wind), but heavy wind will blow rain into the chimney opening. The liner is made of ceramic (at least that's what it looks like). The chimney goes down through the center of the house.

Thanks for any help!

gregzoll 12-25-2012 06:22 PM

Doubt that it is the mortar that is giving off that smell. If the mortar is wet, you have a leak that needs to be fixed, whether it is between the flu lining and the outer block shell, or coming in along the flashing above, where the chimney meets the roof.

joed 12-25-2012 07:05 PM

It could also be an animal like a raccoon living in the chimney. I which case a dampness is not from water but from urine.
No matter what the liquid, cracks in a chimney are not good. You need a chimney inspection by a WETT certified expert

concretemasonry 12-25-2012 08:13 PM

Creosote from wet wood or poor burning practices?

You location/climate might provide a clue.


ChimneyNovice 12-25-2012 11:43 PM

No raccoons
No raccoons, that's for sure. The chimney cap has strong mesh to keep birds out (inspected a few days ago); also burned wood yesterday, no obstruction in the chimney.

I agree about solving what looks like a leak, but does anyone think that it could appear in the mortar between the bricks that far down from the roof and nowhere else?

But the main problem is the sickening sweet smell and how to stop it. You can smell the mortar 4 inches away from the darker areas and it doesn't smell at all. X-14 is strong stuff, and it doesn't phase the smell, neither did bleach.

stuart45 12-26-2012 05:54 AM

Chimney breasts can get infected with Hygroscopic salts, which come from burning fossil fuels. Water vapour is also produced and this can condense higher up the flue. This takes the salts through the flue into the brickwork and plaster.
These salts attract at a relatively low R/H.

stadry 12-26-2012 06:01 AM

my 1st guess, too, dick - the smell of creosote buildup - btw, Merry Christmas & HNY, too,,, spare room's still rdy when/if you get to atl :yes:

might be a crk in the chimney liner or mortar loss between flue liners allowing creosote to collect & gets wet when it rains,,, what's the condition of the liner up where it stands above the conc chimney cap ? is it rotting away ? chimney rain cap's another possibility

try dropping a trouble lite down the chimney & looking - might have to call in a guy w/camera for a better look,,, is there access in the attic to inspect the structure's exterior ?

joed 12-26-2012 08:16 AM

I say almost 100% you have a crack in the liner and the products of combustion are seeping through.
You need a chimney inspection by a WETT certified expert.

ChimneyNovice 12-27-2012 06:36 PM

mortar with sickly odor
Thanks for the replies! When it stops raining and I get over the holiday bug that's got me down, I'll get on the roof, take off the SS chimney rain cap/cover, clean the chimney and inspect the liner as Itsreallyconc suggested.

There is access to the attic, but difficult with the need to move a lot of computer equipment and heavy desk. If all else fails, I may try a Gorilla-type ladder to see if I can climb over everything to get to the attic access panel.

I checked to see what a guy with a camera would cost: $175 to take a look. I can probably buy a used camera for that! Prices here for chimney guys are outside my budget IF I can fix it myself.

Latest attempt in my war against the "perfumed" mortar was to spray it with pet odor killing enzyme solution. When it dries, I'll know, but I don't think it's going to work. So I've tried bleach, X-14, and now this. Doesn't smell at all like creosote, but like some cheap and strong-smelling laundry detergent that is so sickly sweet it makes you nauseous.

Guywithskills 01-04-2013 09:32 PM

They make a cement crack filler by Sika, high tech stuff that comes in a caulking tube. I would insure the chimney cracks are not taking water on when it rains. the outer masonry/stone usually do not get that hot, so it would be fine to use.

concretemasonry 01-04-2013 09:38 PM

Guy -

It takes a little bit of investigation to under stand what is going on in a chimney. Even with 2 to 6 burnings a year with mesquite there may be many reasons for the problem. You have to avoid just going to a big box and buying what your think may be a real cause/solution with an easy to use tube.



ChimneyNovice 01-07-2013 06:55 PM


Thanks for suggesting the crack filler by Sika. Is this a product that Home Depot, for example, would carry? I've been sick lately (and it's been rainy cats and dogs), so haven't gotten a chance to work on the chimney yet. It would be good to have a crack filler on hand when I can. Thanks again.

vintagehouse 05-20-2013 01:55 AM

Vintage House
Hi there,

we`ve recently moved into an old 1860`'s house. (Mid terrace UK).
We also have an extremely sweet smell in our kitchen in 2 places (not chimney). It comes and go`s but it is a sickly smell as you were talking about. No food in these areas, it`s definitely the walls?
did you find an answer or remedy?

tony.g 05-20-2013 07:29 AM


Originally Posted by vintagehouse (Post 1182983)
extremely sweet smell in our kitchen in 2 places (not chimney). It comes and go`s but it is a sickly smell

Dead rat or mouse etc can cause that type of smell.

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