Ultimate Chimney Repair Term Guide

chimney repair terms

While interviewing chimney repair companies, many homeowners found themselves lost in a sea of technical chimney terms.  The chimney repair technicians use words like flue liners, corbelling and creosote as if homeowners use those words every day.  That fact is that no one but chimney repair techs uses those words.  Homeowners in the Washington DC Area tend to be smart people.  However, even the highest levels of education do not teach about chimneys. When providing services like ours, we do our best to share information using terms that are easy for homeowners to understand.  We have created this article to provide homeowners with all of the terms that they will likely need to make sense of the what the chimney repair tech is telling them.  Just take the time to read and digest each of them, and you will find yourself talking like a pro…or at least understand what they are saying. 

Chimney Repair Terms


The chimney is the set of passageways to the exit points for flue gases. The chimney links the points of combustion to the exit point. So, flue gases from combustion get to the atmosphere through the chimney.

Ash pit

This is where ashes are stored. It is usually located at the base of the chimney. It is simply a pit where ashes are stored temporarily before being disposed of.


This is an object that is fixed in any appliance to change airflow direction. The baffle also changes the direction of flue gases and also slows down air-fuel mixtures.


Chase is the area that surrounds metal flue pipes. It is used to stimulate a chimney. There are several variants of chase. Some variants are made of steel while some are made of wood. The external covering of chase made of either stucco or lathe.

Chimney Cap

Chimneys are installed vertically or almost vertically so that the exit point will be facing the sky. So, it is possible for rain, dust particles or snow to enter the chimney to through its opening. It is even possible for animals to get into a home through the chimney when not in use. This is why it is important for chimneys to have a protective cover to prevent the entry of animals, rain, snow and dust particles. The protective covering is the chimney cap.  You may want to read this article to learn more about replacing chimney caps.

Chimney Cleaning and Chimney Sweep

This term is easy to understand. It is exactly what you are thinking. Chimney cleaning is the process of cleaning the chimney. It is as simple as that. Soot, debris, and creosote usually gather in the chimney, and they can block the airflow when they become too much. In fact, the moment they start gathering there, the flow of air will no longer be seamless. So, the chimney has to be cleaned regularly for efficient performance.

Besides, it should be cleaned for safety reasons too. When soot and creosote encounter real heat, they can ignite resulting in house fires. The worker whose responsibility is to clean the chimney regularly is the Chimney Sweep. Learn more about our chimney sweep services here.

Chimney Connector

This is any of the pipes that connect the chimney to any fuel-burning device or appliance. They are usually more than one.

Chimney Liner

The flue system allows smoke and gas to travel from your fireplace up your chimney and away from your home.  The flue liner is the material that is used within the system.  Flue liners are commonly comprised of Terracotta made from clay. 


Corbelling is what happens when bricks are stacked on top of each other and are projecting outwards. This is often seen in the smoke chamber resulting in increased creosote build up that can result in chimney fires.


These are highly flammable dark, tar-like deposits that form when products of combustion (smoke, gas, etc) fail to escape from the flue.  Instead of exiting the flue, they cool and form creosote. Creosote build up within the smoke chamber or flue is a common cause of house fires. 


This is also known as a saddle. This is a long ridge that links the back of the chimney to the slope of the roof. The cricket is required when the chimney is 30″ or wider. Its purpose is to ward water off the main connection between the chimney and the roof.

Chimney Crown

A concrete surface that sits on the top surface of the chimney that sheds water away from the flue liner. There are several types f chimney crowns. 

Below are links to our 3 part series about chimney crowns

Part 1     Part 2    Part 3


This abbreviation stands for Chimney Safety Institute of America. The organization is a non-profit making and tax-exempt organization established to regulate chimney and vent related activities in the United States. It is dedicated to venting and chimney system safety.


This is a valve that comes mostly in the form of a retractable plate. It is simply meant for controlling the flow of smoke or air or both. Most times it is located at the top of the chimney. It opens the top of the flue when the chimney is in use and it closes it when idle. This prevents cold air from coming in and it also prevents warm air that is keeping the house warm from flowing out through the flue.it is the cable attached to the side of the flue that opens and closes the flue.

Direct Vent

Direct vent” refers to a sealed-combustion system in which air for combustion is piped from the outdoors, and the event products are vented to the outdoors. (Got this from an online definition)


The draft is the pressure difference created by a rising gas. The pressure difference draws combustion air into the appliance and discharges exhaust gases to the atmosphere via the chimney

Chimney Flashing

Are metal strips at the base of the chimney as it penetrates the roof. There are two parts.

1- Base or step flashing, butts up against the chimney and is tucked underneath the shingles.

2- Counter flashing- over laps the base flashing and is tucked into the mortar bed joints of the chimney.


This is the link between the chimney and the exit point for gases. The gases from combustion pass from the chimney via the flue to the outside atmosphere. A multi-flue chimney is a single chimney that contains more than one flue.

Flue Liner

This is the inner wall of the flue. It is designed to hold products of combustion. It is done in adherence to the safety rules guiding the installation of chimneys.

Masonry Chimney

This is a chimney made of cement, concrete, stones, bricks or a combination of some of them.


This is a coat of mortar applied to a surface to smooth it out. Parging is often done in the smoke chamber to correct the corbelling bricks.  Some technicians use spray on substances to apply a thin coat to parge the smoke chamber.  This spray on technique does not last long.  The better chimney repair companies parge the chamber by applying thick coats by hand. 


Relining a chimney is the process of repairing/replacing damaged or faulty flue liners. It is the replacement of the flue liner.

Stainless Steel Liner

It is the stainless steel pipe used to replace a damaged liner in a chimney.


This can be described as carbon particle residue that is formed from oxygen-poor combustion. It resides inside the chimney until it is swept out. This is a regular occurrence. This is why chimneys should be cleaned regularly.

Stack Effect

This is the tendency of warmer air to rise within a chimney leaving cooler air at the base known as the stack effect. This is because air is lighter when warm or hot and heavier when cold.

Thermal Expansion

Thermal expansion is the expansion of the metal surfaces of the chimney caused an by an increase in temperature. This does not only happen in the chimney. It also happens everywhere else. Heat makes metals expand.


This could be fixed/permanent or removable. It is the ring situated in the hole where the chimney is connected to the wall. The chimney connector passes through the thimble.


valuable is passage that links the flue collar to the draft hood.

Video Scan

This is not such a technical term. It is video camera and monitor that is installed to inspect the innermost part of the flues that are difficult to access.

Counter Flashing

This is the piece of metal that is placed in the masonry wall to ward off water from the wall and from the roof surface. Counter Flashing is important, as the continuous entry of water can cause issues. There are three basic types of counter flashing – surface mounted counter flashing, reglet counter flashing and through-wall counter flashing (SEE chimney flashing)

Tips for maintaining your chimney

Here are a few important tips for the maintenance of a chimney

It is advisable to use seasoned woods always. This is because using seasoned woods usually slows down the buildup of creosote. Properly seasoned wood should have a moisture content around 20%. The best way to ensure your fire wood is seasoned is by using a moisture meter.

Ensure compact stacking for your fire. It burns longer and more efficiently than loose stacking. You do not need starters like kerosene and gas to start a fire. Using any of them can lead to severe burns. Don’t overlook the importance of a chimney cap. Apart from protecting your chimney from debris, birds and some other small animals can enter through it when they are avoiding predators.



5 Tips For Hiring A Chimney Sweep In Washington DC

chimney sweep tips

There are a lot of cleaning that you can do around your home on your own. However, when it comes to cleaning your chimney and making sure that it is in the best condition possible, you want to rely on a professional chimney sweep in Washington DC. After seeing these signs that you need a cleaning, it is important to hire the right chimney company.  In Washington DC homeowners want companies like ours that will do the job right at a competitive price.  Here are some tips for hiring a chimney company in Washington DC.  

1. Look for a company that believes in preventing problems before they become costly.  

A good chimney sweep looks for future problems in addition to existing chimney.  Some chimney companies only look for blaring problems.  They ignore minor problems in the hopes that they can charge more when the minor issue becomes a major problem later.  The best chimney sweeps look for signs of future problems and make recommendations.  Doing so often results in lower repair costs.  It is always cheaper to address minor chimney issues before turns into major repair needs. 

2. Choose a chimney sweep that offers additional services

You want to choose a company that can help you in a variety of different areas.  Doing so allows for you to take full benefit of their expertise.  Otherwise, you will ultimately end up hiring more than one company – and there is simply no reason for this.

Some of the most common services offered include:

  • Cleaning of chimney
  • Masonry repairs
  • Flashing repair
  • Waterproofing of chimney
  • Crown and caps repair
  • Purging of smoke chamber


In addition to cleaning the chimney and fireplace, it is also beneficial to look at any other services that the company might offer, such as dryer vent cleaning. After all, once you find a company, it’s best to rely on them for various other services around your home as well.

3. Read Up on the Chimney Sweep Companies Reputation

You should always look into the reputation of the company.  Your research should include sources such as online reviews, testimonials and their membership with professional organizations like the Chimney Safety Institute of America (CSIA).  Past customers reviews are a powerful resource.  If a large number of homeowners in your area have good things to say about the company, you are likely to have a similar experience.  Positive reviews will help you makes sure the company that understands how to sweep a chimney in a professional manner.  Taking a little bit of time to investigate the company before you hire them will ensure that you get the best services at the best possible price.

4. Find Out About Chimney Sweep Licensing

Washington DC requires that companies who provide chimney services to be licensed.  You want to make sure that the business that you choose is licensed and insured. Being licensed shows that they are professional and have taken the proper steps to be compliant with the regulations.  If you allow a company to come in and they are not licensed or carry adequate insurance, any damage could potentially be your responsibility.

5.  Ask for a Quote

You also need to ask for a quote for the services that you require.  Pricing should be relatively straightforward. When you get into repairs and installations, the company might need to come out and provide an inspection before they can provide a quote.   Most companies charge for inspections and cleanings.  However, they should not charge a fee to provide a price quote.  Unfortunately, there are some cases where a quote cannot be given without performing a full inspection. 

5 Ways to prevent costly chimney repairs

chimney repair maintenance 

When you own a home with a chimney, it’s important that you practice maintenance throughout the year. This will make it easier to prevent costly chimney repairs. Otherwise, you could end up spending a significant amount of money to repair your chimney.A recent job that we did in Ellicott City, MD is an excellent example of how acting quickly can reduce chimney repair costs.  Many of the most common repairs can be avoided when you know what needs to be done.

1. Use the Right Fire Wood

There are many types of wood that you can burn in a chimney. Any seasoned hardwood can be used. If it hasn’t been properly dried, the moisture can lead to problems, including creating more soot and ash that will lead to a clogged chimney. It will also increase the risk of fire inside the chimney, which is a danger.  Here is a good article on how to tell if your firewood is seasoned. 

“Green” wood should be avoided. If you buy firewood, look to see that it is seasoned so you can avoid issues.

2. Clean Out Ash from your Fireplace

Ash should be removed on a regular basis. Every time ash reaches the bottom of the grate in your fireplace is an indication that you need to clean it all out. It will make it easier for you to keep the air flow moving correctly. It only takes a few minutes after the fireplace has cooled, and can make a big difference in the long run. Cleaning supplies are sold everywhere, too, making it a simple task.

3.Get an Annual Chimney Sweep

Hire a professional chimney sweep once a year. They will be able to come in, provide a thorough cleaning of the chimney, as well as look for any potential issues. The sweep will know what to look for and can catch issues before they become problematic. This will also keep you “in the know” regarding the health of your fireplace.  We recommend considering our services

4.  Call for Chimney Repair When You See a Problem

The moment you see a problem, call for a repair. Some of the most costly repairs are because homeowners ignore the problem. Further, don’t focus on cost alone when choosing a chimney repair service. The “cheapest” repairs are often cheap for a reason – and you don’t want to pay twice to get the job done right.  Be sure to ask the chimney sweep company these questions

5.  Don’t Try To Fix Your Chimney Yourself

A DIY approach can be dangerous, especially if you don’t know what you’re doing. It’s best to hire a chimney sweep contractor who has a good reputation in your area. Also, one who uses floating cast chimney crowns is desirable because of having quality techniques to get the job done right.

In the end, you’re in control of the maintenance performed on your home. Having a fireplace and chimney can be a great feature in the colder weather, however, you need to know what can be done so you can avoid costly repairs throughout the life of your chimney and your home.

Complete chimney rebuilding project in Ellicott City

before chimney repair

Before rebuilding the chimney 

after chimney rebuild
After rebuilding the chimney

We were called to do an estimate for chimney repairs in Ellicott City, the home of Mrs. Whelan . Before we got there, she had already received 2 or 3 other estimates from other companies. The estimates she received had differing opinions on what was needed to be done. Needless to say, I’m sure she was expecting to get more confused with what we were going to find and was probably a little skeptical about the whole process.  

When we arrived I just simply went on to do my evaluation of the chimney and fireplace as I normally would. Throughout the process as I found issues and defects in her chimney and fireplace I would go over them with her, so she fully understood what the situation was and how we needed to correct them.  I quickly discovered that this was going the chimney was in need of more extensive work than an earlier job that we did in Ellicott City.

chimney smoke chamber

smoke chamber
The first issues we found were in the smoke chamber and the flue liners for the fireplace. The smoke chamber was corbelling and not parged smooth as required by the NFPA 211 and the IRC. The second issue was that the first flue liner was cracked. I explained to her that the smoke chamber needed to be parged smooth with Chamber Tech 2000 and that the flue needed to be relined to correct her issues.

smooth parged chimney smoke chamber

stainless steel chimney liner
Here is the new stainless steel liner installed and the smoke chamber after it has been parged smooth with Chamber Tech 2000. This will allow for better air flow in the chimney and minimize the amount of creosote buildup in the chimney.

before floating cast chimney crown repair
Before floating cast crown installation

after floating cast chimney crown repair
After Floating Cast Crown Installation

The top 21 courses of the chimney had bricks that were starting to spall. The hairline cracks were already visible, and it was only a matter of time before the faces of the bricks would start to pop out. A lot of the damage started from the crown and worked its way down the chimney. Once we rebuilt the chimney, we installed a new floating cast concrete crown with a 1.5″ overhang that sits on a stainless steel plate to allow water to run off the drip edge if it ever penetrated the 5″-6″ on concrete. With this crown, the water will never run down inside the chimney from the crown. All Pro Chimney Service understands that the crown can make or break the chimney that why now we only install floating cast concrete crowns on chimneys we rebuild to ensure that it will last for years to come to protect your investment.  You can learn more about floating chimney crown installations here. 

B-Vent Installation

before chimney b-vent installation

chimney b-vent installation

Mrs. Whelan, also wanted us to look at the B-Vent chimney for her gas boiler and water heater. She had several companies tell her that all she needed to do was replace the top section of B-Vent above the roof and replace the chimney surround (fake metal chimney). Upon my inspection of the situation, I found that the existing B-Vent was disconnected and did not meet the proper clearance requirements needed to combustibles.

chimney b-vent in Ellicott City, MD
chimney pipe in ellicott city., MD

The B-Vent at some point got disconnected and as a result had the vent leaning against the top plate framing. It should maintain a 1″ minimum clearance to combustibles per the manufacturer’s specifications. Also in the attic, the chase cavity did not have a fire-stop installed. I also determined that the B-Vent could just go straight up through the roof instead of having an off set in the attic which just meant more materials and more restrictions in the venting. I explained this to Mrs. Whelan and her family, and we determined that the best option was just to have the B-Vent terminate straight up. We patched up the hole for the old vent location and installed new flashing for the new B-Vent.

*The roof will be getting replaced next.

Chimney Chase Rebuild In Bowie, MD

chimney rebuild bowie, md

We were called out to rebuild the chimney chase in this home in Bowie Maryland because the chase blew over during a storm. Luckily we did not need to install a new fireplace.  Our work was focused on the chimney (venting).  This job is an example of where repairing the chimney required the chimney to be rebuilt. This particular chimney has been discontinued making it harder to get parts. Luckily one of our distributors had some left in stock. As a result, we were able to save the homeowner money. 

chimney repair in bowie, md

Here, we are prepping our work area and setting up the scaffolding to start the chimney rebuild.

nails fastening chimney chase

chimney chase repair 
This is the reason why the chimney chase blew over. The builders barely used any nails to fasten the chase to the house. This vertical 2×4 which secures the chase to the house only had three nails securing it to the house.

lower chimney chase portion
This is the original chimney that was left, we removed it and installed the new chimney because this one was damaged.

The lower portion of the chase was insulated, but the insulation was not sealed off. The insulation should be sealed off so that it won’t fall onto the fireplace or chimney. Sealing it off also prevents drafts from coming into the house through the chase. Homes that have issues with a drafty prefabricated fireplace most likely lack insulation, and the insulation is not sealed.

thermo poly insullation
We installed Thermo-Ply to close up the insulation in the chase and installed the new chimney sections. Afterward, we cleaned up the debris and loose insulation at the bottom of the chase before installing the fire-stop.

built up chase

As we built the chase up we used framing nails and Ledger Lock to secure the vertical 2×4’s of the chase to the framing members of the house.

chimney chase fire stop

Here we have the 2nd fire-stop which is at the 2nd-floor ceiling height.

framed sheathed chase
Here, we have the chase fully framed sheathed with 7/16 OSB.

chase wrapped with tyvek

After the sheathing was installed, we wrapped the chimney chase with Tyvek home wrap and taped the seams. This will also keep the chimney/fireplace from being drafty.

completed chimney chase with reworked siding

Here is the chimney chase after the new aluminum siding was installed.

stainless steel chase cover
Here is the chimney chase above the roof with a new stainless steel chase cover and chimney cap.