Fireplace and Chimney Parts: Diagram and Anatomy

Anatomy of a Chimney

There’s far more to chimneys than meets the eye. While the average home owner is only vaguely familiar with the contents that extend beyond the hearth and the chimney, your fireplace and chimney could consist of up to 22 parts. Knowing about these parts and their functions can be useful in general maintenance, troubleshooting, or even talking with a fireplace and chimney expert about your service. Use the following guide to understand the various parts of your chimney, and be prepared for your annual chimney inspection!

chimney flue liner chimney crown/wash definition chimney flue definition chimney smoke chamber definition chimney mantle definition chimney throat damper definition chimney throat definition chimney lintel definition chimney hearth definition chimney smoke shelf definition chimney hearth extension definition chimney firebox definition chimney ash dump definition chimney ash pit definition chimney foundation definition chimney cleanout door definition chimney footing definition Image Map

1. Chimney Crown – Your chimney crown protects your chimney from water damage entering through small cracks. Without a proper chimney crown- or if you have a cracked one, rain water seeps into the bricks and mortar of your chimney structure. Even minute amounts of water can result in brick flaking, mortar deterioration, and unsightly salt deposits on your chimney. Without a good crown that has been sealed your chimney does not have any protection. Eventually, the bricks and mortar break up enough that the chimney is no longer structurally sound. You can read more about chimney crowns here.

2. Flue – A flue is simply a passage for conveying exhaust gases from an appliance to the outdoors. A flue may be a duct, pipe, vent, or chimney. An unlined chimney is technically a flue, even though an unlined chimney is a fire hazard.

3. Flue Lining – For a safe flue, a lining must be used to ensure minimal accumulation of flammable debris. This lining should be stainless steel or specially formulated lining tile. In our all about chimneys article we talk further about the importance of the flue lining and problems you may be facing with your flue lining.

4. Smoke Chamber – The purpose of the smoke chamber is to gently compress the byproducts of combustion into a smaller space (the chimney) without causing back draft. The use of sloping walls, in conjunction with good fireplace design and maintenance, helps facilitate this.

5. Chimney Damper – Chimney Dampers are lever or pulley activated doors within your chimney. They can be closed to prevent energy loss when your fireplace isn’t being used. They also help prevent rain water or animals from entering your home if your chimney cap doesn’t restrict this. Wondering how this relates to a chimney cap? This article explains.

6. Smoke Shelf – This shelf is just behind the chimney damper. Flat, it catches falling debris and rain water, and helps with the transition of large volumes of smoke into the small chimney.

Chimney Chase – This generally refers to a factory made case used around factory made chimneys. This function is taken by masonry chimneys in homes that have them.

Anatomy of a Fireplace

7. Mantle – Also known as mantel piece or mantel shelf, this piece of hardware is more than a surface to display family photos and hang stockings. It’s primary use was to help catch smoke and prevent it from entering the home, but as fireplaces have evolved its use isn’t as important as it once was.

8. Lintel – This piece is place just above the fireplace opening. Lintels are used in archway, door and window openings to help bear the load created by opening such spaces.

9. Throat – This is the space just below the damper and just above the firebox, where the fire first passes through.

10. Firebox – The firebox is the section of the chimney system in which a person builds a fire. A proper firebox is lined with firebrick, a substance of refractory ceramic, which can become cracked or weakened after years of use. This area of the chimney is often in need of repair. It is recommended to have a thorough inspection of the firebox every five years or so depending on fireplace usage.

11. Hearth Extension – This is the space that occupies the floor just outside of the firebox. It’s made of heat resistant material such as tile or brick to reduce the chance of fires.

12. Hearth – This is the space on which the fire actually burns. As with the firebrick, it must be able to handle both the potential corrosiveness of the burned material and the high heats it can be subjected to.

13. Ash Dump – Lies directly below the ash door dump, this is the space ash falls through once the ash dump door is opened.

14. Ash Pit – Below the ash dump, this serves as a collection space for dumped ash. It should be emptied frequently to prevent excess accumulation of flammable byproducts.

15. Clean Out Door – This door is used to clean out the ash dump. It frequently is located outside or in the basement to make ash removal easy.

16. Footing – This is the horizontal surface under the ash pit. Generally made of concrete, the chimney should be securely placed in relationship to the footing to prevent problems later on.

17. Foundation – The lowest part of the chimney walls, this is made of heavy duty brick or cinder block. It’s used as structural support for the rest of the chimney, and is exposed to potentially hot ash. As such, it should be sturdy.

Fireplace Face – This is the area between the mantel and the fireplace itself. Traditionally brick, it must be sturdy enough to handle the heat of the fireplace below it.

Ash Dump Door – This door allows you to easily remove ash from your firebox. Placed in the middle of your firebox, it can opened to dump the ash into the ash dump.

26 thoughts on "Fireplace and Chimney Parts: Diagram and Anatomy"

James says:

Hello. I am looking for some advice. I have what appears to be a combustion air flow opening on the outside of my chimney at about firebox level. I also have two sets of vertical open slits on chimney inside the house, below the mantle. When a fire is going, these interior slits push hot air into the house and help warm the room. But, when I don’t have a fire, which is most of the time, I can feel very cold air being pushed into the room. It seems very inefficient. What can I do to stop these slits from pushing cold air into my house when I don’t have a fire. I assume they are needed for when I do have a fire, so I can’t close them up with fire rated mortar?

Dale Howard says:

You are right, it’s very inefficient. That fireplace design sounds better in theory than it works out to be in practice, as you have learned.

You can approach this a couple ways. One is to plug the slots completely and leave them that way. This obviously makes it so you never get the heat. The other is to put in a plug and take it out when you want heat.

Personally I favor just plugging the slots and being done with it, but that’s a personal choice you’ll make. I have this for you though: use ceramic wool. It isn’t real easy to come by, it’s a little expensive (compared to fiberglass insulation for example- but don’t use that stuff!) and will not catch on fire. You can probably get the little bit you need from a chimney sweep.

My other suggestion is to paint it black so you don’t have to look at “white stuff” tucked in the holes. Black is a better appearance. Just use spray paint once it’s in place.

If it’s any consolation, when the masonry gets heated up it will keep giving heat for a long time after the fire is out. You won’t get as much heat, and you won’t feel it the same way, but a lot of it will still be there. Hope this helps.

James says:

Thanks. I wound up closing them up with fire rated mortar. I am planning on replacing the old drafty steel firebox with an energy efficient wood burning fireplace insert. Any suggestions?

Dave says:

An efficient Insert is by far the best way to go.Regency has a bunch of good ones. Call me if you want a free estimate 410-255-3525.
Dave Liddle Sales Manager Highs Chimney Service.

Kris says:

I have a problem becausejust a little smoke gets in living room.Chimney is clean.Any suggestions?

Dale Howard says:

There’s a few things that can cause smokey chimneys. Typically, its caused by draft issues; here’s an article on that:

Dennis DeGrafft says:

I am looking for the massonary walls that are in three pieces in my fire place , I take out three screws on each side and the wall on the right side and left side come out, these right and left side hold in the rear side, my rear side is broken, do you sell these replacement parts? I would have to measure the three wall s in the fireplace but they look like 18 inches high 24 inches long and 1/2 inch thick. Sincerely: Dennis DeGrafft

Dale Howard says:

Hi Dennis,

I have panels which are 22×39 x c.1″ thick (7/8″ or so), and would cost $170 plus shipping which will be by common carrier. If you are in Maryland, you can come pick it up. Hope that helps.

David Wood says:

Im having the same issues with my firebox walls cracking and crumbling. How do I contact you to purchase the walls you have for sale? Can I purchase each wall separately or do they come in a set?

Dale Howard says:

You can call High’s Chimney at 301-519-3500 and ask for Dale; they will direct you from there. You may buy one or more, as you like. If you are in our service area we would of course love to replace them for you, but we do understand many people have the skills and desire to do this sort or work themselves.

Carl Belken says:

I have an old Blaze King Fireplace Insert that was purchased back in the mid 1980’s. That I am having a problem with.

This model has/had a catalytic converter at the top. It has two fans at the bottom that draw air in and push it up around the converter and out into the room. It’s thermostat is on the right hand side. Above the thermostat is a lever you push in to open the draft door/damper.

My problem is that draft door. It started with it being difficult to open. Now, it won’t open at all. The catalytic converter broke and was removed in pieces. I had replaced it myself only a few years ago. I was surprised to find that the converter just sits up there and is not bolted in. It’s held up by a bar of metal in the firebox. From the firebox I could see no problems so I pulled the insert out from the fireplace a little ways.

Once out you can see the draft door from above. I took a shop vac and vacuumed it out. the hose was too big to fit in the slot so I rigged a 1/2 inch plastic hose onto one of the Vac’s hose attachments. I then ran that hose around through the inner core of the insert. I did pick up some ash and pieces of creosote. I did not do a good job because the pipe was too flexible and I could not see what i was doing. Once I had the insert out I found that I could open the draft door easily by reaching through the firebox and pushing it open.

I saw no broken parts. In fact I saw no reason why the door should not open normally. I shot a small amount of WD-40 on the joints and hoped for the best but the door still would not open by it’s push lever AND it will not stay open once it’s pushed in. It always wants to fall back in the closed position. To keep it open you have to run a poker through the firebox and hold it open.

I did go to Blaze King’s website and downloaded the manual for my stove. It was not much help. It showed a cutaway of the insert but I did not learn anything that I did not know already. I almost forgot to tell this part. There was a small amount of creosote pellets on the floor of the old fireplace. The fireplace was built in the early 70’s and has a clay liner that’s maybe two feet in diameter. There is no connection between the liner and the insert. I’m probably wrong on the size.

Do you have any idea what’s wrong? I am a old guy who is disabled. What I just mentioned above would have taken a young person 20 to 30 minutes. For me it was quite a days work. Yes I should hire somebody but I am a stubborn old fart who refuses to give up on life.

Dale H Howard says:

Glad you haven’t given up on life! I’m not old yet but I’m not young anymore either and pretty sure I don’t have the energy you do. That’s one seriously thorough job you did here.

Bottom line is I don’t know either. These things do have a useful life and do start to break down toward the end of it. 25+ years of service is pretty good and you’re already into borrowed life with a woodstove.

Maybe you can find the answer and keep this stove chugging along for some more years. Still, if you plan to live a bunch more years- and if you’re that stubborn I’ll bet you do !- it might pay to treat yourself to a new stove so you can enjoy the next 25-30 years. Sorry I can’t help more.

Alec Patton says:

Hi, I’m hoping you can help me when other experts have failed!

I live in a mid-50’s Cape Cod with the chimney at one gable end [pretty typical setup]. There is a fireplace in the living room on the first floor, and another fireplace in the finished basement immediately below. The living room fireplace has a small cast-iron hatch [ash dump door?] in the floor of the firebox that leads to a cleanout accessed from the outside by a cast-iron door. The hatch is rusted shut, but is loose in the masonry and can be lifted out.

In the 1990’s a renovation was done where a new mantel/face was installed, also a [matching] stone piece was placed in a cutout in the wooden floor in front of the fireplace for the outer hearth. The fireplace has screen doors and glass doors.

Whenever I use the fireplace in the living room, the basement immediately starts to get smokey, and after about 15 minutes it is like several guys were smoking cigars in there while playing poker.
The weird part is that I can’t figure out where the smoke is coming from. It is not coming from the basement fireplace, which has glass doors that I also sealed with packing tape. It might be seeping out the can lights set in the ceiling.

So 5 years ago I dutifully hired a well-regarded company to do an inspection. They shoved a camera up the chimney and concluded that there had been a chimney fire, as the clay liner had large vertical cracks in it (1/4″ max). After a couple years (and saving some money) I solicited bids from four different firms to fix the chimney, and I told all of them the same story and all of them said that relining the chimney would solve the problem. So I hired one; they demolished the old liner, put in a new steel one, redid the chimney crown and concrete shoulder (all the brick otherwise looked fine), and caulked the cap of the unused basement flue shut, but the problem REMAINS UNCHANGED. I also used some refractory mortar to fill some gaps I thought I saw in the cleanout pit (from the outside). This also did nothing. I am at my wit’s end. I surmise that the smoke is coming out somewhere through a gap that is inbetween the basement ceiling and the first floor, which perhaps was created by the previous homeowner when the mantel/fireplace face and outer hearth were redone.

My main problem is that the basement ceiling is plaster, in a nice swirled pattern that would be impossible to patch or duplicate if I ripped out the ceiling in that area to get a look inside. Do you know what is causing this smoke problem? And if it can’t easily be repaired, is the smoke getting into the basement a fire hazard? As it is, I just bite my tongue and crack open a basement window and turn on the fan in the basement bathroom to vent out the smoke, and make sure to change the furnace filter even more quickly, as soot does show up in the filter after a couple days subsequent to any fire. Thanks in advance.

Dale Howard says:

Hi Alec,
I can’t diagnose it for sure from here, but I have some pretty good ideas you will want to investigate.

Let’s start with this: every smoking problem is a pressure problem (see If there is a negative pressure (vacuum) relative to the outside of the house, the air/smoke will move to equalize the pressure, simple physics. It’s also true inside “the envelope” of the house. If the upstairs has a vacuum relative to downstairs, there’s air movement to equalize that pressure as well.

And remember this: when you burn wood or run the furnace, you use air for combustion which you send up the chimney after you’ve used it. If you send air up the chimney you have to replace it. In the past this was not an issue because houses were leaky enough that replacement air entered the house through lots of cracks etc. Nowadays houses are tight and replacement air is prevented from entering. Not to mention we use kitchen fans, bathroom fans and radon fans to further depressurize our homes!

There’s also what’s known as stack effect and it can be powerful in Cape Cod and old steep pitch roof farm houses. The upstairs or attic can be so much warmer than the rest of the house it makes a better chimney than the chimney itself. I do not think this is the problem though because the fireplace on the first floor would probably smoke if it were. Still, don’t rule it out until you know for sure this isn’t it. If the problem is worse on very sunny days in the winter this could have something to do with it.

A test for that would be to crack a window on the first floor on the windward side of the house (usually the north/west side; but wherever the wind blows- open it on that side) and see if this helps. Obviously you can’t keep the window open all the time but if it works you know you have a replacement air problem.

Back to the obvious: smoke is migrating from the either the fireplace system inside or coming back in from the chimney outside. You have the basement sealed off so I guess it’s not that, but the obvious tells us it’s coming from the fireplace/chimney system. I suggest going further in sealing up the system. Have the smoke chamber parged (or spray-sealed with Chamber Cure Pro or something similar.)

Smoke chambers are the most overlooked area of the system, and a lot of them have a lot of holes in them. Bad mortar, missing bricks, wrong kind of bricks used etc. There are lots of problems in smoke chambers so they need to be sealed up too. It’s not always easy to find someone to do this work because it either requires special equipment (spraying) or it’s work nobody likes to do – pretty much at any price!

My guess? You seal the smoke chamber so smoke can’t migrate just because that makes sense regardless. I wouldn’t worry so much about whether it’s getting in through the light fixtures or somewhere else; stop the smoke at the source. Then you arrange for replacement air, which can be done with an outside air kit (as opposed to keeping a window open all winter J ).

Todd Watson says:

Hey Carl,

Not sure if you figured out your problem with the damper but the dampers I am use to using stay in position by friction between two surfaces. Which surfaces depends on the damper. Yours sounds like the handle is needed to offer the friction to hold the door in position but the handle sounds as if it has detached from the damper. So you have a damper door that freely moves, as it should, but a detached handle that if stuck in position. Not sure of how to fix it without seeing the setup. Being a stubborn diehard myself…I hate to say it but… may need to call someone.

[…] Parts of a Chimney – Anatomy of a Fireplace – Chimney Guide […]

Alec Patton says:

Thanks for the thorough response, it’s appreciated. I have heard of parging basement walls beofre to stop water leakage, but not parging of a smoke chamber. Presumably that particular product has refractory properties. As you say, the question is now finding someone with a sprayer and the knowhow to do it!

ed says:

alec… i would never have two fireplaces on one chimney….as dale said it causes pressure/draft problems…they need two for each fireplace.

[…] Fireplace & Chimney Parts | Fireplace & Chimney Diagram & Anatomy […]

steve balas says:

I’d like to find the sliding fireplace doors my father bought from Sears in the ’80s. Any suggestions. Or if those can’t be found I would like to be able to close the doors without the air sucking out the chimney and making a constant sound. I guess the entire fireplace door would need to seal. Would this be an ‘air tight’ door? The sliding door did not make any sound when the doors were closed.

High's Chimney Service Inc. says:

I deal with chimneys so it’s not actually my area- I don’t know the brands and sources, but that kind of door is still out there: you’ll find it. Those kind of doors these days are higher-end doors and will likely be a little more expensive than average. They’re very nice. You should be able to get them from a good hearth dealer, one who handles better lines of doors.

Good luck, stay warm!

tom woosley says:

hi,great diagram of the fire place.i have built several solid masonry fireplaces,but never a chimney for a wood stove which i am about to do for my landlord.this must draw right.with out a smoke chamber and smoke shelf, how do they draw?also do i run flue tile down to the footer,or fill the chimney to the level where the stove pipe enters the chimney? thanks so much,,,,tom

tom woosley says:

t ask the above guestion and u replied to run the flu tile down to about 2 ft above the footer.i then came back and ask how to support the tile 2 ft above the footer. now i can’t find ur response to my first question or my 2nd question.can you help with that? thanks again,,tom

yussuf rasheed says:

pls i need details on the principles of chimney i.e how it operate

High's Chimney Service Inc. says:

The reason smoke goes up a chimney, or does not go up a chimney, is ALWAYS the same. The difference in pressure between the inside of the chimney and inside of the house.

Generally speaking, it’s hotter inside the chimney because of the fireplace, woodstove or furnace below (natural draft appliances). So the smoke is warmer than the air in the house. The molecules of warm air are further apart than less-warm air. This would be the definition of a relative vacuum. You could define the smoke as being pushed up the chimney by the higher-pressure, denser air (ie the lower-pressure less-warm air) or as the air in the house (that denser air) being pulled up by the vacuum in the chimney. A matter of semantics in the description, but you get the idea: the warm air in the chimney is a relative vacuum.

And when smoke doesn’t go up the chimney, it’s because the pressure in the chimney is greater than it is in the house. That could be for a lot of different reasons which come from inside the house or outside. Regardless, smoke does or doesn’t go up a chimney because there is or isn’t a vacuum relative to the inside of the house. This is ALWAYS, even if for a wide variety of reasons.

One other note: Fan assisted appliances (ie not natural draft) actually push air into the chimney. In this case it’s not the warm air creating a vacuum but the forced air, so the relative vacuum exists between the chimney (higher pressure) and the outdoors (lower pressure.)

Hope this helps!

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