A Simple Overview of Chimney Repairs

Masonry Chimneys

Most chimneys are masonry, but sometimes, they are prefab (more below)

Masonry chimneys are built differently, and sometimes are a bit more complex. At least there are a few more parts that need to be covered.

Ash Dump Area

If you have a wood-burning fireplace, you probably have an ash dump. 

And if you do, then it should be free of any combustible material within the ash dump area. Especially house framing. 

The next time you’re cleaning out the ash dump, check it out with a strong flashlight. 

If you see that any part of the house framing is visible, do not use your fireplace until it is corrected. 

If hot ashes are going into the ash dump, you run the risk of the hot ashes catching the framing of your house on fire. That puts your whole house at risk to catch fire. 

The ash dump should have a tight-fitting door installed where you scoop the ashes out and a tight-fitting cover installed in the firebox floor where you push the ashes down into the ash dump. 

Both the ash dump door and the ash dump cover should be made of noncombustible materials (i.e. they won’t catch on fire). 

If either the ash dump door or cover is missing, please do not use the fireplace again until those are replaced.

Chimney Cleanout

A chimney cleanout is different from your ash dump, but they are often confused for one another.

A chimney cleanout is an area where debris can fall from the chimney flue. It’s fairly easy for the debris to build up. If a lot of debris has accumulated, you should clean that out (either a DIY project or just give a chimney company a call).

Cleanouts are usually found in straight flues for freestanding wood stoves, furnaces, or boilers.

The cleanout should extend at least eight to twelve inches below the thimble.

And it should be sealed with a tight-fitting noncombustible door. You should replace the door if it is missing or broken.

Firebox Area

The firebox is where you build the fire. 

The firebox should be lined with refractory firebrick, which means that it is capable of withstanding the high heat of the fire. 

It’s not uncommon for us to see that the firebrick is cracked. Or the mortar around the bricks is weakened by hot fires or years and years of use. 

If you don’t have a cap, or you have some other issue causing chimney leaks, you could have rainwater coming down the chimney that will also weaken the mortar holding the firebrick together. 

When you use your fireplace, the firebox area takes the biggest hit. So you should watch this area very closely. 

If the firebricks are loose or if the bricks have cracked more than 1/4 inch wide, then the firebox should be replaced before being used again. 

Dampers

Every fireplace needs a damper. But not every fireplace has a damper. 

If you don’t have a damper, you should get one installed. The damper keeps heated air from escaping up the chimney when it’s not being used. 

An open fireplace without a damper will allow more heated air to escape than a window open all winter! 

The damper also helps keep some of the heat generated by the fire from escaping up the chimney but still allows the smoke to escape. 

Replacement parts for damper repairs are usually available for newer dampers. You can call a local chimney company to help locate these parts. 

If you can’t find the parts, you’ll need to just replace the damper.

Smoke Chamber

The most common repair to a smoke chamber is the parging of the smoke chamber walls. That means we apply a coat of mortar to the bricks to smooth the interior walls. 

During a chimney, fire parging is often cracked and damaged. 

A certified chimney sweep or experienced bricklayer should be able to parge or reparge your smoke chamber for you.

Mortar Crown

The mortar crown is the concrete or mortar piece at the top of your masonry chimney. Its purpose is to keep water from entering the chimney chase. 

A proper mortar crown will overhang the edges of the chimney by about an inch or two to keep water from running down the sides of the chimney. 

If your mortar crown is cracked or damaged, you’ll either need it rebuilt or just have the cracks filled in.

Flue

The most common repair that we do when it comes to flues, is relining. There are many reasons to consider relining your chimney

Repairing Damage

Chimney flues are often damaged by chimney fires, lightning strikes, and other harsh weather events. 

But your flue can be damaged by settling or even deterioration from age!

Proper Sizing

Chimneys need to be the proper size to work properly. When we’re installing a new flue, we use a formula to help gauge how large your flue should be to properly vent the gases out. 

Some people assume that just having a flue is enough. So they do a DIY solution instead of calling a chimney sweep. 

And they end up using a flue that is either too big or too small. 

If your flue is too big, you risk having excessive creosote & tar glaze built up. 

If your flue is too small, you risk not having enough room for all the gases to vent. Which causes the smoke to release into your home! 

Upgrading Old Chimneys

We’ve worked on homes and chimneys older than the Constitution. 

Many old homes were built without a chimney flue liner. If you have an old flue, you should get one installed for safety’s sake. 

Regardless of the condition of your chimney, safety and efficiency will be immediately improved when you install a chimney liner. 

Converting Fuels

You may want to convert your furnace or boiler from one fuel to another. When that happens, relining becomes an important consideration. 

If you’ve converted your heating system from oil to gas heat, your chimney could present unknown hazards unless you’ve had the chimney properly inspected and maintained. 

After oil to gas conversions, the sulfur deposits left from years of oil-burning oil mixes with water vapor produced by the new gas appliance. 

What you’ll get is an acid that attacks the bricks and mortar in the chimney. 

The brick and mortar deterioration can lead to blockages in the venting system that may allow carbon monoxide to spill into the home. 

This deterioration occurs rapidly and should not be ignored.

Relining Materials

If you elect to have your chimney relined, you should be aware that there are four different kinds of relining materials

• Clay Flue Liners
• Stainless Steel
• Aluminum
• Cast-in-Place

Clay Flue Liners

These are still the primary choice for brand new construction. But they can be used for relining. 

Relining with clay flue liners is a tough job, though. It may require cutting open one wall of the chimney to remove the old liners and install a new one. 

Since the clay liners come in two-foot sections, they must be properly seated and mortared at each joint. 

Lowering the clay liners down the top may not produce satisfactory results and is only possible in straight chimneys. 

Stainless Steel

Stainless steel is what we recommend most of the time. 

They’re available in round, rectangle, or oval shapes. Can be made of flexible or rigid construction. 

Stainless steel liners are also insulated to help maintain flue gas temperature within the liner. It also prevents heat transfer to nearby combustibles. 

Stainless steel liners can be insulated with either a ceramic fiber blanket or a mixture of cement and vermiculite. 

The best part about stainless steel liners is that stainless steel doesn’t rust. And most of the liners we see offer a lifetime warranty!

Cast-in-Place

These are interesting.

Cast-in-Place liners are exactly as they sound. Just a mixture of cement and insulation material around a mold to create a new flue liner. 

The liner is cast in place. 

There are two common methods to form the flue. 

First, we use a bladder that is installed in the chimney and sealed down at the bottom. The mix is pumped and poured around the bladder and allowed to cure. 

After curing the bladder is deflated and removed leaving a new flue. 

The other way is pouring the mix around a vibrating mold and drawing the mold up through the chimney as the mix is poured. 

Aluminum

Masonry chimneys may also be lined with aluminum liners. Aluminum liners shouldn’t be used to vent anything except certain gas-fired appliances.

Aluminum liners aren’t suitable to vent gas logs installed in woodburning fireplaces.

Factory Built Systems

It’s pretty safe because they go through some serious testing before they can be installed.

The bad part about factory-built systems is that you can’t substitute fireplace parts from one manufacturer to another.

If the manufacturer of your chimney system has gone out of business, then you don’t have a way to properly fix your chimney.

It’s very important to use only the recommended parts for a factory-built system. Something as insignificant as a set of glass doors can have a serious effect on the overall operation and safety of the system.

Before replacement parts can be ordered, you’ll need to find the manufacturer and model number of your system. You can usually find the nameplate somewhere on the unit.

But sometimes the nameplate is located in the firebox and is unreadable after just a few years.

If the nameplate is missing or unreadable, then hopefully you have the owner’s manual. It’ll have all the information you need.

Common repair items in factory-built fireplaces include the floor panels and refractory wall, the mesh screen or curtains, the chase cover (the metal pan that covers the top of the chimney structure), and the chimney cap.

How to Hire, What to Look For

1. Can the company provide references? 
2. Does the company carry a valid business liability insurance policy? 
3. Does the company ensure that a certified chimney technician will be on the job? 

If they guarantee all three of those, then you are in a good spot. The technicians don’t necessarily need to be certified by the CSIA, but I do recommend putting in a bit more due diligence before accepting a certification that’s not by the CSIA. 

This is because certifications are a tricky thing, especially in an unlicensed industry like ours. Any company can craft a list of job-related questions and sell them as an exam and certify those who pass. 

Certifications

I recommend you take a few extra minutes in your research before making your hiring decision to learn more about the certification the company has. Here are a few tips to make sure the certification is reputable:

• Is the word “certified” just part of the business name or is it an earned designation?
• Is the certifying body a for-profit business or non-profit?
• Does the certification need to be maintained and renewed through continuing education as the industry evolves, or is it well enough to be certified through a one-time exam?
• Is the certifying body well-established or are they relatively new to the scene? New doesn’t mean “bad” but you should make sure the requirements for certification are more or at least equally stringent as those of more established certifications
• Is the mission statement of the certifying body focused on educating and protecting homeowners or is it more focused on making it easier to earn a certification?
• Does holding the certification require following a code of ethics?

If you can answer all of these questions, then I think it will be safe to allow the company in your home to work on your chimney.

Please note that If you are hiring a chimney company to install a cap for you, most of the time, they will need to buy the cap themselves. This is primarily for liability and insurance purposes. 

Besides, it’s probably cheaper for them to buy a cap at the dealer discount than for you to buy one at retail cost.

It doesn’t matter if you are in Roanoke, Lynchburg, Blacksburg, or some other city anywhere in the USA — if you have any questions about the safety of hiring a chimney company, please don’t hesitate to email me at mitchell@patriotchimney.net or call me at 540-225-2626. I’m happy to help!