This Old Chimney Part 1

Common Issues Found In the Chimneys of Old Houses

Old Masonry Chimney

An Old Masonry Chimney

If you own an old house or at least an older house, you will have different considerations than those who own newer homes. Newer homes are more likely to be built following modern codes and with materials that conform to modern published standards.

This means newer homes are more likely to be safe. This doesn’t necessarily mean that your old home is unsafe, however. You just have to know what you’re looking for and bring certain conditions up to proper safety standards. This article will guide you through the considerations specific to your chimney and educate you about your options.

Types of Fireplaces in Older Homes

By “old” we mean houses more than 60 years old. The fireplaces and chimneys in older homes are almost certainly masonry based. The metal, factory built hearth systems are found mostly in houses built after the 1950s. Most masonry chimneys are made with bricks, though there are also block chimneys.

Why You need To Improve Your Old Chimney Before Using It

Lack of lining is one of the most common issues that we see in older chimneys. As a flat statement, any chimney that is not lined should not be used for any purpose. You may say, “Well, it’s been there for 80 years, so why change it now?” and that’s a reasonable question. In some cases the answer is that nothing has changed – the situation has always gotten worse! The reason why your chimney’s condition has gotten worse is because most things wear out over time and a chimney is certainly no exception to that rule.

Additionally, the fact that furnaces and stoves of 2011 require a more capable chimney to support them makes unimproved, older chimneys more or less obsolete.

Why Chimney Linings Are So Important

Installing Chimney Lining

Installing Flexible Chimney Lining

Here are a few reasons why chimney linings are so important:

  • Unlined chimneys have bad draft characteristics. These bad draft characteristics cause the appliances they serve to work less than optimally.
  • Unlined Chimneys may leak noxious gases into the living space.
  • If used for gas, modern appliances have such low-temperature flue gasses that they produce huge amounts of condensation. With an unlined chimney, the condensation is allowed to adhere to the actual masonry. This ruins wall paper in the house, and the freeze-thaw cycles in the winter slowly demolish the masonry chimney.
  • If the chimney is used for wood burning, the condensation can also help form tar and creosote, which is flammable. In this case, they pose an unnecessary fire danger.
  • When you make a change to the construction of a structure, the system must come up to building code standards. So if you have a new furnace or boiler, a woodstove or insert, the chimney must be lined at that time.
  • You may find yourself without insurance if you make changes without improving the chimney. Check with your insurance company if you intend to disregard the advice here or consult a certified chimney sweep.

Basically, have your chimney lined as soon as possible.

Block Chimneys in Old Houses

Block chimneys do work, but as a general statement they are less than desirable. Block chimneys are really meant to be surrounded with bricks. They are more subject to cracking, leaning and leaking; most any problem you can imagine. As a general statement, if you have a block chimney built right against the house it’s probably not legal and if you have a wood-frame house you probably ought to just tear it down. However, if you can build brick around all four sides, unlikely in most situations, you can get the clearance to combustibles called for in the codes, the chimney can be serviceable.

Old Brick and Mortar Chimneys

Old brick chimneys have their own set of problems. Fortunately, older bricks are often actually better than newer bricks. It’s the way they were fired that makes the biggest difference. That’s why you see some houses from the 1800s or even 1700s where the bricks are still in great condition. Yet you’ve also probably seen modern houses with the faces of the bricks popping off. So if you have an old house, you probably have pretty good bricks!

Shifting Ground and your Old Chimney

The ground is always moving a little bit. Fortunately houses are actually a bit elastic, or at least allow enough give that they don’t split in half when the ground heaves an inch. But over time, those stresses can break bricks. If you have that problem in your chimney or walls of the house, it’s probably visible. Broken bricks are just a fact of life sometimes. You might need to replace them eventually.

Old Masonry Chimney Degradation Due to Weather

Sun, wind and rain are hard on any masonry work, especially the mortar. There are so many different types of mortar and concoctions of mortar cement that there’s no guessing how long your mortar is supposed to last, but suffice to say 60 years on a chimney is a long time.

When the mortar wears out it’s either time to rebuild or re-point. Re-pointing is the process of grinding out about an inch of the old and broken up mortar and putting in new mortar without removing the bricks. Unless your chimney is quite large, it may be just as easy to dismantle it and rebuild using the same bricks.

Waterproofing Your Old Chimney

One thing about those great old bricks is that they soak up water from the rain. On the sunny or windy side of the house that’s probably not a problem because they dry quickly. However, in shady areas the bricks can hold water and in the winter that water can freeze. This type of problem is usually visible. There are good water-proofing materials such as ChimneySaver by Saver Systems which do not block the pores of the masonry. Whatever you do, don’t use silicone, such as Thompson’s, because silicone blocks the pores and it has a shorter life due to UV light breaking down the silicone.

Your Old Chimney Crown (Or Lack Thereof?)

There’s another aspect of the chimney that’s almost always lacking on older homes, and that’s the chimney crown. The crown is the cement part on top of the chimney that keeps the rain from going into the structure below. The crown catches more sun, wind and rain than all the rest of the chimney, and it is usually not as thick as a brick. Crowns are almost always cracked. I can’t think of one crown I ever seen that wasn’t cracked. If the crown is bad enough, it needs to be taken off and re-laid. If it is cracked but still structurally sound there are good materials to coat the crown, which will save money.

Regardless, you should have the crown coated with CrownCoat by Saver Systems or some similar product. If you put up a brand new crown, coat it so it doesn’t break up again.

How to Deal with Lack of Clearance to Combustibles

Clearances to combustibles is something they didn’t worry about in the old days. It is quite common to see wood beams or 2x4s right against the masonry of a chimney. When there are fires in old homes, it’s also common to find that some of this wood ignited. Oddly enough, the process of pyrolization takes place over many, many years. The unscientific definition of that is that the ignition temperature of wood gets lower over time. In other words, it takes less heat to catch it on fire 50 or 100 years later than when it was new.

Chimney Insulation

The way to deal with that is to make sure you have a liner installed to zero-clearance (insulated). The only alternative is to tear out the walls and cut away the wood. Practically speaking, nobody is going to do that, and even if you do, there’s no guarantee you’d get it far enough away. Take a look in the attic and remove wood you find against the chimney up there. That’s not so hard to do.

Removing Debris and Blockages From Your Chimney

At the base of an old heater flue, usually in the basement, there can be all kinds of debris. Sticks and leaves, dead birds, or maybe a lot of soot. Old oil furnaces may have released sulfuric acid in the chimney for years and worn the chimney out from the inside. Aside from that though, the bases are often just blocked by debris. Just be sure to have a chimney sweep come out to make sure it’s open. If you have a flue that was converted from oil to gas, you would be venting carbon monoxide into the house. Be sure to have this checked, and especially if you or your family have a lot of colds or headaches because this could very well be carbon monoxide poisoning.

With regards to that debris in the chimney, many older homes are “finer homes” that are surround by trees or perhaps in a semi-rural setting with lots of animals and leaves. That being said, a chimney chase cover is smart to prevent debris from building up as well as protection from harsh weather conditions.

Read Part 2 for more on old chimney problems!

16 thoughts on "This Old Chimney Part 1"

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michael l dahke says:

I have a question. I have an older fireplace. I would date it back to the 60s. early sixties.
The brick is smooth and has a dull sheen. I know it’s not a soft break , if that makes sense.
My problem, there are a couple of sections that are about 4 courses of brick where it appears to be shifting out at the corner or edges of the fireplace. ( OUTSIDE NEAR THE TOP AND ALSO ABOUT FOUR FEET DOWN ) Not a lot, but a few inches ….noticeable.
I’ll be sell the home and wondering what the cost of such a problem might be. I can definitely see tuck pointing is in order.

Dale Howard says:

Many chimney sweeps do handle this sort of problem, though you will want to ask over the phone to make sure they handle masonry repair. This falls under the category of “small masonry repair” (versus something large like tearing down the whole fireplace and chimney) so there’s a good chance you will find a sweep that does the work. High’s does if you are in our area.

It’s really not possible to guess costs from where I am, as you might imagine. My suggestion is to get at least two quotes, three if you feel you still need it after the second. You are interested in price of course, but pay close attention that you have real confidence in the contractor. You could be so sorry if you wind up with the guy who charged $100 less but made a mess of the job. A decent job is more important than the last dollar, and generally does cost more than the hack job. Just be careful in hiring.

Connie Jones says:

Well you are full of scare tactics and information that you are making up out of your head. It’s no wonder that you’re struggling financially. You can’t use made-up information or stuff “you heard” to build a business with. Instead lay off the bull and get out and do some hard work. It will pay off in the end and customers will start to trust you. Sure it may sound good and help you feel important to write put-downs like “check with your insurance company if you intend to disregard the advice here”, but the truth is that hardworking people like to keep thier money instead of giving it to you. My insurance company is none of your business but you bring it up to add some kind of authority to your message. “Uh, oh, he mentioned my insurance company… he knows something special, I’d beer listen and give him all kinds of money”. For example I have an unlined brick chimney built in the 1920s, sure there are some cracks in the mortar here and there and a few loose bricks. Why wouldn’t there be? It’s old! I have a oil furnace and a woodstove vented into it and both work fine. The chimney sweeps around here shrug thier shoulders and help me clean it every year. And for a nice fee. Everybody’s happy and everyone’s safe. And Warm, with cash in our pockets instead of in your pocket. None of this money-grubbing “I’ll have to tear that down” or acting all self-important about trying to act like they are in charge. Scare tactics might work on old ladies who you rob with your slick talking, but millions of homes in America have really old, unlined brick chimneys and that is the way to keep things. For instance I helped build a new one for a friend’s house and was told that there was absolutely no reason to line it, except to line the chimney contractor’s pockets like yours. We aren’t dumb someone you think because you have a business you have an education? Like “oh, if you said so, then OK, I’ll give you all the money you want, in fact I’ll just sign the house over to you”…

Dale H Howard says:

Wow, I hardly know where to begin. We have never even met so imagine my surprise at this. Apparently you had an encounter with a chimney guy that didn’t go well. Let me make a general response; there are a couple issues here I think should be addressed.

First, most “chimney customers” expect their sweep to know codes and standards and make observations and recommendations based on that knowledge. They’ve just forked over money to presumably make them safer and they want to know what the sweep has to say about their systems. Most folks understand that a chimney man makes his living fixing chimneys so are not surprised if he proposes some repair or improvement.

In my experience, the people we serve are are intelligent folks and not afraid to say NO. They listen to what the sweep has to say and evaluate it against a battery of things, such as trust, budget and money. Just as you did. The difference is most folks don’t conclude the man is a money-grubber if they want to say NO, they just say “no thank you.” Most folks see him as a man (or woman) doing his job.

Secondly, about whether or not a chimney should be lined. The NFPA and the IRC both say that chimneys must be lined (caveat: a chimney two bricks thick does not have to have a liner, but this is seldom the case.) The position that a chimney doesn’t need to be lined will fall apart on just a little research into the matter. This is not hidden knowledge.

Appliances are engineered to work best with specified venting systems. And modern appliances, either wood stoves or gas/oil furnaces/boilers, are all much more efficient than they were many years ago. These appliances all put vastly more stress on chimney than in the past. The “rules” that applied 75 years ago don’t apply today- chimney need properly sized liners now more than ever.

Whether for containing the products of combustion or for containing unfriendly fires, it is widely understood that chimney liners make homes safer. This is not “information that I am are making up out of your head” Those standards and codes were developed for a reason- to keep us safer, as well as the house that surround ours- not to inconvenience us.

Third, insurance companies and lawyers are just part of the air we breathe in America. What they think should matter to us, whether we like it or not. In our litigious society and it would be foolhardy for a professional sweep to sanction an unlined chimney. If for no other reason he should recommend it to cover himself (to say nothing of that it’s the right thing to do.)

Fourth, most folks are not surprised at all by a recommendation to fix loose bricks. It sounds like your chimney has been working for 90 years, and that’s great. They don’t last forever and they do require some maintenance. Cracks and loose bricks are expected after 90 years, yes. And it’s expected someone will fix them so they don’t get worse and worse and worse…

Last and most important of all- do I understand that you have two dissimilar fuels vented into the same flue? That is absolutely against most written codes or standard (including in our area), and for good reason. Short of writing an article here about the dangers of carbon monoxide poisoning I’d like to point out that CO is an even bigger danger than chimney fire and your venting situation has you at increased risk to both (relative to the average person.) Please reconsider your position and have two liners installed to separate the venting of those two appliances.

I do agree that “You can’t use made-up information or stuff “you heard” to build a business with.” Below are some relevant objective expert resources consistent with the advice we have provided in this article. – National Bureau of Standards study on Masonry Chimneys and Fireplaces – international residential code on chimneys

Connie Jones says:

Yes, OK, the information you have is sound and solid. I see that you are not just making it up. I’m sorry I over reacted because the tone of the original article, intended to be helpful and properly authoritative came across as forceful and condescending. I think that the internet is a wonderful resource but all too often the written word can contain more meaning for the reader. There are 9 ways to interpret ” I would like to help you with your chimney”. Emphasizing each word lays down a particular emphasis. In that phrase I think the word “help” should be emphasized, but this isn’t always the case. If the first word, “I” was emphasized by the reader and then the words “your chimney” were mistaken by the reader as being holier-than-thou, then it would come across very differently. The so-called flat statements you make about tearing down a chimney abutting a house are better worded as “in my experience, I advise clients to tear down a three-wall chimney that is installed against the house”. Or your general statement about never using unlined brick chimneys, ever, could be more digestible if re-worded as “unlined brick chimney’s are dangerous and I’ve seen many house fires (and/or near-death carbon monixide poisonings) from people using these, and while there are many fixes or solutions that are elegant and highest-end, there are also more budget-sensitive alternatives depending on your needs. Contact me and we can talk over some options”. You say the same information in both methods but the first method that you used makes it sound like you are the nations expert and everyone ought to listen to you.

I realize you are just writing an article, but the article conveys a tone about the author, and given you are a helpful (and/or lifesaving) business first and an authority on physics, architecture and thermodynamics second, then putting yourself out there to be possibly misperceived as someone trying to profess the ultimate truth, might lose customers that you never had.

I’m sorry that I came off as hostile, you didn’t deserve that and again I apologize. The work you do is hard and I’m sure you are constantly battling previous homeowners knowledge, that they got from, for example, a roofer who thought the chimney “looked OK to him” and didn’t need repair, or an unethical appliance salesman who made a quick buck on the water heater but installed it into the clean-out of an unlined, single wythe chimney with a splayed top and disintegrated lime mortar just holding the bricks by virtue of luck and gravity.

Anyway, there are four walled chimney’s safely installed on the side of a house , there are also double wythe brick chimney’s that are serviceable, let’s say for a venting a propane hot water heater, but still an aluminum flexible flue liner with an attractive crown and topper might make the homeowner be safer and also be the envy of her neighbors. Inviting a second look by you and a free estimate based on your years of experience could get you in the door and have more service calls if people feel comfortable. And if I, a general internet surfer, can get a false impression that you are not humble and grateful for the work you do, then others might get the same impression.

To clarify, I called my sweep, he assured me I have it wrong. I don’t have one chimney for my house, I actually have one separate one for the oil furnace, lined and blocks (but is a “four wall” against the house), one for the hot water heater (single wythe and unlined), and one separate one for the woodstove triple wall stainless steel. The sweep has ordered the flue liner material and will be fixing the bricks and re-pointing, or re-building from roof-up as necessary. The vent for the water heater is still in the clean out for that main brick chimney so I guess I’m stuck there, but with a cap to keep the dead birds out, I guess it will have to do. The only other option is to continue the building more chimney below where it already rests in the basement floor. Or get rich and buy an instant flash hot water heater and do a direct vent out the side of the house. Any case, do you see an immediate issue with using the clean out as the point of entry for the water heater, given that the chimney will have a liner and cap? It’s not like there will be ash or creosote building up in there. The off-gasses from the propane water heater are exactly the same as the ones from the propane stove, and there is absolutely no chimney for the stove in the kitchen. The gasses just float around in there. I think it’s funny that everyone is so scared about the hot water propane burner but no one cares or advises about a special chimney for the stove in the kitchen.

So do you agree, a four walled chimney can be safe and might not need to be torn down just because it is against the house. That part of the article really stuck me. Generally if you reach conclusions without actually seeing it yourself, it might come across wrong.

Thanks for the site and the references.


Dale H Howard says:

The reasons for lining for a gas heater are generally different than lining for solid fuel. Gas exhaust in a large flue often (always?) condenses and leaves the inside of the flue wet, at the very least. There can be (probably are?) spillage issues as well, and that can be discovered by using a CO detector. Outside chimneys are particularly at risk because they are “cold chimneys” and there’s not only more condensation but also freezing and thawing of the masonry in the winter, assuming temperatures get cold enough for that in your area.

The reasons for lining on a solid fuel unit are sort of the same, though CO poisoning isn’t the same issue- not because CO isn’t there (for it is) but because you’ll smell smoke as well if it spills. Sort of a built-in warning system. But all that black tar left in the flue is flammable, so you get a fire hazard to boot. The chimney physics are the same though, so it’s always appropriate to have the flue properly sized to the appliance regardless of the fuel being used.

When you line a chimney, especially an outside one, be sure to have it insulated. While that’s less important for and inside chimney, there are no liner manufacturers of listed chimney liners that do not require insulation for liners venting wood. And it’s just a really smart idea for gas (and oil, but especially gas) flues because it’ll reduce condensation and/or spillage a great deal.

As for tearing things down and rebuilding, it depends. Is the brick structure sound? If it is, I think I’d just line it. If the mortar is shot it may be smart to rebuild instead of tuck-pointing, but that’s usually a degree-of-deterioration and budget decision.

Hope this helps.

eastcoastmason says:

Connie, what is your backround in masonry construction ???? what experience do you have????? wow your lengthy post is quite disturbing to say he least…honestly about halfway through i wanted to start poking my eyes out….good grief …i bet you live alone ” obviously “… and have about 8 cats and many prescription bottles….lmao !!

Paz500 says:

Ditto what eastcoastmason said! Wow… What nerve.

DJBrown says:

Mr. Howard,
Thank you for your invaluable article on This Old Chimney, Part 1. Like the reader above, I have a 1920’s home as well, in the mountains of N.C. and your article above answered many questions for me. My chimney does need to be replaced, it never had a chimney cap and has used coal heat, wood heat, gas heat and back to wood over 84 years. Over the years, birds nested regularly in it. When I had to purchanse a newer wood stove a few years ago, it had become code in NC to have a liner. What was a surprise was the debris the installers had to clean out of the chimney before they could install the liner and the newer stove. You are right about brick breaking down, weathered elements, mortar deteriorating, the need for a chimney cap and a liner. In fact, it is an insurance liability not to have attended to those things in NC. My chimney has been tuck pointed several times in places many times before the cap and liner were installed, but now the mortar has so deteriorated bricks are falling out in some places. I live in a rural area with rural chimney sweeps who after five estimates, found only one of them recommended tuck pointing again. One gave the option of applying mud, lathing, and two more coats of mud. Because the chimney has actually moved off of center by a few inches, and the deterioration of the top third (most exposed to weather, wind and western sun), we agreed (after me having had these discussions with four previous masons) together the chimney needed to be taken down to the roof and rebuilt. You are right about the bricks being better in older homes, as well. The bricks in my chimney were fired on the home site from red clay and the chimney mason is planning to reuse them. That was hopeful news because it saves around $500.00 for a pallet of bricks and because the mortar is so deteriorated, he says it will be fairly easy to clean and reuse them. You are also right about getting multiple estimates and asking lots of questions over and over of each man. Every workman has a different perspective on the problem and project. Some prices are very high and some are questionably low, too. One needs to find out from them what their own chimney is like inside, and the multiple estimates help. For example, one gentleman wasn’t as familiar with an old double brick home and their single brick chimneys therefore, recommending two pallets of brick. That was $1000.00! just for brick. He did not suggest using the old brick which meant more expense and difficulty matching brick. I didn’t know about any of this so it has been a trial and error process for me, but am more knowledgeable about another aspect of my old house. The reason I landed on your website today was because I needed to know if the old brick could be used. Thankfully, you had a wealth of information that provided confirmation of what my home needed.

Dale H Howard says:

The answer to your questions is “it depends” plus something that’s more opinion that fact.

Since using the old brick works in your favor when have to match brick and you have enough to do it, and since using new brick can work against you in the same way (maybe you can’t get a good match for old stuff) you might have a bit of Catch 22 going on. “It depends.”

Best I can say is what I’d do at my own house. Assuming the old brick is in pretty fair condition, I’d try to use it just to maintain a consistent look. You may or may not save much money because there could be considerable labor in cleaning it up enough to use. And if you’re caught in the middle with not having enough good ones to do that, the trick is to rob some bricks from a less visible place and replace those with your new bricks.

Good luck!

–Btw, I’m glad the article was useful. Thanks for “stopping in”!

Deneteus says:

This was an interesting read. Thanks for the info.

Leslie Butler says:

Hi! I have an old masonry chimney and a natural gas boiler, my chimney is crumbling on the weathered side and is probably 8′ high to clear the roof line….
I was wondering if I could take down the masonry chimney to the roof line and replace it with a steel liner and steel chimney?
My chimney runs on the exterior of my house(if that makes a difference).
Thanks for any info you can send my way!!

High's Chimney Service Inc. says:

The answer is yes, with one caveat. You need to make sure you have the proper size metal chimney there. For example, if it’s for a fireplace it will need a larger flue than a gas furnace. You might also consider lining the chimney down to the appliance (i.e. have a chimney liner running below the metal chimney you put up)

The piece is called different names by different manufacturers, but if you refer to it as a “masonry anchor plate” everyone will know what you are talking about.

Go for it, and Sweep’s Luck to you!

Jj says:

Hi! Thanks for the great article. I have a question though:

I just started taking down the brick & mortar chimney of my 206 year old house built in 1909. Do I need to worry about asbestos in the mortar or bricks? Having the mortar hit my skin, it’s itchier than anything.

Also, it looks like part of the brick is inside the wall in the house. It’s a 1 story but I’m wondering if the chimney doubled as a load bearing wall.

I’m going to rebuild the chimney with the same bricks at the back of the house,

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