This Old Chimney Part 2

Problems With Older Chimneys Continued

In this two part series, we’re discussing typical problems that owners of old homes have with their chimneys. This Old Chimney Part 1 begins the conversation that we’re continuing this week.

Chimney Smoking Issues

Fix a Fireplace Smoking Problem

Smoke Stains on a Fireplace

If you see smoke on the face of the fireplace above the lintel (The thick metal bar that holds the bricks across top of the opening,) it is a sign that the chimney is smoking. This is fairly common issue with old chimneys. There are a few reasons why chimney airflow problems occur.

Older houses are usually not very air tight; in fact they’re more likely to be drafty. But maybe the house has new windows and doors, the walls are tight etc. so maybe the house can’t breathe. This can cause a change in air pressure that hurts the drafting process that causes smoke and gasses to rise up the chimney. It’s unlikely that an old house can be sealed up so effectively, but it is a possibility.

More likely is that the flue is either blocked or was never properly sized. Proper sizing means that there is a relationship between the size of the flue and the opening of the fireplace. Think of this in a ridiculous extreme: if you had a flue the size of a soda straw you would not expect a fireplace to draft properly. There are ratios that work or don’t work. That ratio can be changed with a smoke guard. These are commonly available from hearth shops and chimney sweeps. Glass doors usually will help a chimney smoking problem as well.

Gaps in the Chimney Bricks: Fixing Fireplace Air Leaks

Fireplace Air Leaks

Gaps in the Bricks Causing Air Leaks

There’s often a space between the bricks on the front of the fireplace (the wall, or the “face bricks”) and the structure of the fireplace itself. Sometimes that gap is on the floor by the hearth (in front of the wood burning fireplace too.) Not good. These gaps are probably caused by the old house settling over time.

You should inspect the fireplace carefully with a bright light to see if any wood is visible. If so, stop all action and call in a professional CSIA Certified Chimney Sweep. Wood in this area can cause fires quite easily and is a real safety hazard. If you don’t see anything, then get a chimney sweep to pack the gap with ceramic wool and refractory cement. Packing the hole yourself with typical cement won’t work because of the extreme temperatures in the fireplace.

Common Hearth Issues

Did you ever wonder how the hearth “stays up” that is to say: what supports all that weight? What’s under those bricks and that heavy firebox? The answer could surprise you- sometimes very little! Or sometimes, commonly found in old houses, there’s wood. Not good.

Go to the basement and look up to see what’s supporting the hearth. If you have metal I beams then great (I’d be surprised if you do.) Perhaps it’s supported on a masonry foundation, and that’s good. Or if you see cement that’s probably fine too, while it’s not clear what’s holding the cement in the air (though something obviously is) at least it’s not combustible.

But if your hearth is supported by sitting on a piece of plywood, you need to change that. More than one house has burned down because of that sort of thing.

Improving the Smoke Chamber of your Old Fireplace

Fireplace Smoke Chamber Parging

Parging the Smoke Chamber of The Fireplace

Above the damper area is the smoke chamber. This is the area where the wide fireplace funnels up to the smaller flue. The bricks are stepped in, or corbelled. That’s a rough surface, and it makes for a) less draft, b) more heat transfer though the wall c) a dirtier chimney. And modern codes say they should be parged. Parging is the practice of spreading some sort of cement over the corbelling to smooth out those square steps. This is not something you can do yourself. Somebody has to open the back of the smoke chamber (take bricks out) and reach through the hole to parge. Alternatively there are materials that can be sprayed (sort of like Gunnite, only it’s a different material.)

Call a chimney sweep and ask him if he’s able to spray or parge the inside of the smoke chamber. You may need to make a few calls to find somebody, because the work isn’t easy and it’s not fun. But it’s worth doing- the smoke chamber is usually the weakest part of the system next to the chimney itself.

If you’re lucky, that area is already parged and the parging is holding up well.

Common Old Chimney Problems

Well, that wraps up our conversation on old chimney problems. Have questions? Old home stories? Let us know in the comments section!

8 thoughts on "This Old Chimney Part 2"

nancy says:

This is very helpful but we have a 100+ year old chimney that goes through the house and is exposed in the attic which was recently insulated and renovated to use as part of the house. The chimney has been lined to use with a pellet stove and is swept every year. However, the bricks of the chimney in the attic which are exposed are leaking creosote onto the floor of the attic and there is leakage all the way down the chimney to the ground floor (there is creosote staining appearing on the ceilings at each level). How do we fix this?
Thank you.

[…] of flammable debris. This lining should be stainless steel or specially formulated lining tile. 4. Smoke Chamber – The purpose of the smoke chamber is to gently compress the byproducts of combustion into a […]

Dean says:

Hi Dale, do you mind if I put this article on my website it is great information, I am a WETT inspector and so many clients have these questions. I will reference the author. Thanks in Advance.

Dale Howard says:


We’d welcome that. Thank you. Btw, what’s your website?

Richard L says:

Hi, I have a safety question regarding an 85 year old fireplace made from granite stone. The chimney appears to have been “built to last” many years ago but after this long, obviously the mortar has deteriorated. I’m looking for tips/advice regarding how to know when an old fireplace is in danger of falling/collapsing? The fireplace does have a little bit of a lean to it, ie, not perfectly vertical, but it is not extremely pronounced…. but a lean is detectable visually. Also, I notice it has already lost one granite stone off the tip top. I know old fireplaces can have a stone pop out occasionally but I wonder what steps I should take to insure this thing doesn’t collapse and, say, crash through the house (causing major damage) and/or worse, injure somebody inside the house. I don’t see any terrible immediate danger. I’m just operating under the principle “an ounce of prevention is worth a pound of cure.” I know some of probably have much more knowledge/experience in this area than I do. Thank you for any info/ideas/comments you may provide.

Richard L says:

Additional info: The above-mentioned fireplace goes through the center of the house. It isn’t on the outside of the house except for, of course, the part stickin’ out of the roof. And the roof is fairly steep, perhaps a 45 degree angle even. If the fireplace needed removing, how do you remove it under those conditions? I was imaging a crane like they use in tree removal… with a person and bucket suspended so they don’t have to stand on the roof. Thanks again.

Our home is nearing 90 years old. It’s 2016 now and it was built in 1928 here in S.W. Pennsylvania. We don’t know much about it. There is a chimney going from the basement to through the attic and roof that is in pretty good shape. We don’t exactly know how this was operated other than at one time there was a coal furnace used as evident by an exterior loading door and ‘coal room’ for storage of coal. The wall where the furnace was used has been cemented over. I am dying to know if this home can be made to burn wood in it and use the chimney again? Any help with this would be gratefully appreciated more than you know. Thanks in advance.

High's Chimney Service Inc. says:

The short answer is yes, you can probably burn wood. In fact, I’d be surprised if you can’t but, as always, “it depends.” And I only mean that in the very general way; nothing in particular suggests that you shouldn’t be able to.

The thing to do is bring in a guy who’s been doing chimneys for a long time and ask him what the possibilities are. It’s hard to imagine you can’t at least have a wood stove, and it may be possible (if you want to spend the money) to alter things to the point that you could have a fireplace. Bear in mind as you ask questions that a contractor’s masonry experience or lack thereof could well reflect in his answers and proposals. You might then want to talk to someone who could offer the masonry work if it’s an option at all.

Good luck!

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