9 Common Causes of Chimney Leaks

We recently provided chimney repair services in Silver Spring, MD on a home with a chimney leak.  This time of year we encounter more chimney leaks than during the drier season.  It’s common to have your chimney develop some leaks.  The scariest part of it is that you can have a chimney leak without realizing it.  Unknown leaks can lead to potential hazards and costly repairs if left untreated, so it’s important to have a regular chimney sweep and inspection done by a certified chimney repair company. Some types of chimney leaks are not as dangerous, but they still cause damage to your home because moisture gets where it should not be. Here is a short list of the most common causes of chimney leaks:

 No cap or cover on the chimney

 repair missing chimney cap

 A chimney that is open to the sky lets rain and snow fall inside and cause that wet campfire smell to permeate the room. It also gives animals and birds opportunities to build nests. Things pile up, and your chimney could be blocked, leaking carbon monoxide into the ho

Damage to the chimney crown

chimney crown damage

That sloped layer of concrete, the chimney crown, is what keeps water from damaging the mortar in the bricks beneath it. It also seals the gap between the liner and the outside chimney. When it has little cracks, the freeze-thaw effect makes those cracks grow bigger. It’s like losing shingles on the roof.  If your crown is damaged, there will be leaks.  We witnessed this problem with a chimney repair project in Ellicott City, MD Be sure to read this article on repairing chimney crown cement

 Deteriorated or improperly build chimney shoulder

chimney repair

 The shoulder of the stack, the sloped area on the stack where it transitions from a broad base to narrow, is a common area where the masonry deteriorates and is the cause of leaks, or it is just not constructed well enough to hold off rain and snow.  Here is an example of a chimney in Columbia, MD that was poorly constructed resulting in leaks.  Often it is built without a proper pitch to allow the water to run off, and as a result, it soaks and leaks its way into the chimney.  

 Deteriorating mortar & masonry

damaged chimney

The Chimney Safety Institute of America says water and your masonry chimney is a dangerous mix. The result of prolonged water contact rusts metals in the stack structure, and the porous masonry holds water that allows mold in warm situations and the freeze-thaw effect when it’s cold breaks down the integrity of your building.  We frequently see this problem when doing chimney repairs in Washington DC. 

 Inadequate flashing

chimney flashing repair
The flashing is supposed to be the flexible connection between your chimney and roof that lets each side expand or contract without making a gap between them. If the flashing needs to be repaired or replaced, you will see leaks around the chimney.  This is a common problem in Washington DC.

 Rusted chase cover

chimney leak silver spring, md

 Often when the builders install prefabricated fireplaces, they will install a galvanized chase cover which sits flat on top of the chase. When snow sits on top of it, it weighs it down and allows water to puddle up causing the galvanize chase cover to rust out and allow water to leak into the house. A certified chimney repair company can install a new stainless steel chase cover which won’t rust and is pitched to allow the water to run off.

 The wrong chimney liner


 Your chimney liner must be sized based on the appliance it’s serving, if the flue is too big for the device(s), the flue gasses will condensate. For wood burning appliances, this means excessive creosote build up which can lead to chimney fires and for gas appliances this means moisture build up in the flue system which can cause the masonry to deteriorate and cause the moisture to leak out into the house. A certified chimney repair company can reline your chimney with the right size liner.

 You need a chimney cricket
chimney cricket installation

“Cricket” is the term for a water deflector that is installed where the roof rises from the chimney. It is an excellent idea for a steep roof or chimneys more than 30 inches wide. As the rain runs down the roof toward the chimney, the cricket moves the water to the sides and on down to the gutter.

 There’s a clog in your chimney


 Leaky chimneys can cause moisture damage to the point that bricks fall into the chimney and clog it up (commonly seen in older homes that are not lined) or an animal builds a nest in the chimney clogging it up. Whatever the case maybe, if the chimney is clogged there is a problem with the airflow, which could result in no heat and hot water or a more severe type of leak — carbon monoxide.

So how do you keep these causes of chimney leakage from causing trouble? By making sure, you have a regular chimney inspection by a reputable chimney repair company. That way, the source of the leak is identified by the people who know what the problem is and can fix it. No matter what kind of leak you have in your chimney, letting it continue to be there guarantees your problem will get worse.


Chimney Repair: Chimney Crown Series Part 3

Welcome to part 3 of our chimney repair series dealing with chimney crowns.  In parts 1 of the chimney crown series we discussed crown sealing.  Part 2 of the chimney crown series concerned replacing concrete crowns.  In this final part of the chimney repair series about chimney crowns, we will review building a floating cast concrete crown.  Floating cast concrete crowns are very common in Silver Spring, MD and other parts of Montgomery County.   However, we are starting to see them across the region. 

The chimney crown is the layer of concrete sitting on top of the last row of brick, and its purpose is to shed water away from the chimney. It’s normally 3″-4″ inches thick and starts high around the flue liner then slopes down to the edge of the bricks. The chimney crown is the first line of defense for the masonry, once the crown fails the chimneys become prone to leaking, and the masonry below will soon fail after.    

Floating Cast Concrete Chimney Crown

Floating cast concrete crowns are a great option when rebuilding a chimney crown with a leaky history. This type of crown does not make contact with the bricks below it. We install a stainless steel sheet over the bricks then pour the concrete on top. This ensures that the crown will not leak.  If the water penetrates the crown, it will shed off of the stainless steel sheet underneath. The casting for the crown gives it a 1 1/2” overhang past the bricks below to give it a drip edge so water does not run down from the crown.  Be sure to read this article about a floating cast concrete crown that we installed in EllithEllicott City, MD.

How to install a floating cast concrete chimney crown

  1.       The original crown on top of the chimney is removed, the surface is cleaned, and we check the top course of bricks to make sure that they are not loose.
  2.       We build the form for the crown using 2×6’s and 2×4’s to give it a 1 1/2″ overhang past the bricks below it.
  3.       We set the stainless steel sheet over the bricks and wrap the flue liner(s) with foam for an expansion joint.
  4.       We set the rebar on top slightly elevated to reinforce the concrete.
  5.       We mix the concrete and add PWR waterproofing powder to the concrete mix.  Mixing in this way ensures that the new crown is waterproof as soon as it’s dry.
  6.       We pour the concrete tap on the form to make sure the concrete settles in.
  7.       Once it’s dry, we come back to remove the form and seal the expansion joint

 Before Floating Cast Chimney Crown Repair

This chimney in Takoma Park, Maryland had a severe leak issue. The right side of the chimney is pretty much hollow below the soldier course and every time it rained water would leak into the ceiling next to the fireplace. The homeowners had the crown rebuilt and repaired by different companies, but it still leaked. The last thing done to it was a crown sealant the cracked, peeled and failed. They even had the chimney tuckpointed and waterproofed in hopes that it would stop the leak, but it didn’t. When I came out for the site visit, I determined that the problem was the crown and my recommendation to them was to do a floating crown.

During Floating Cast Chimney Repair

Here we have the forms for the crown built with 2×4’s and 2×6’s. The stainless steel sheet is in place. The pink foam around the flue liner is for the expansion joint, and the rebar is set but not raised yet in the picture to the right.

After Floating Cast Chimney Repair

Here you can see that the crown has the overhang around the chimney and is about 4″ thick at the edge.

Here you can see the stainless steel sheet underneath the chimney crown. We did seal the space between the brick and the stainless steel, but we purposely do not seal between the crown and the stainless steel allowing the water can run off if it penetrates the crown. Adding PWR waterproofing powder to the concrete mix has waterproofed the crown. 

** The tuckpointing repairs on this chimney were performed by another company before All Pro Chimney Service repaired the crown.

Chimney Repair: Chimney Crown Series Part 2

This is part 2 in our chimney repair series about chimney crowns.  In part 1 we discussed chimney crown sealant.  We also discussed that chimney crowns are the concrete layer that sits above the brick that is used to shed water away from the chimney.  The Chimney crown runs around the flue liner and extends to the bricks.  Failing chimney crowns is one of the common causes of chimney leaks.  Without professional chimney repairs, leaking chimney crowns can cause the masonry to crumble and fail.  

In this blog, we will go over what takes place when replacing the concrete crown.  Concrete crowns must be replaced when the original crown has failed and cannot be sealed.  

How All Pro Chimney Replaces Concrete Crowns

  1.       Remove the original crown, clean the surface and prep it for the new concrete.  This is done to allow the brick and new crown to adhere correctly.  
  2.       Apply a bonding agent with a brush to the entire surface area. 
  3.       Waterproof the new crown by mixing PWR waterproofing into the concrete mix along with a bonding agent.  This step ensures that the crown sticks to the bricks properly.  
  4.       Reinforce the crown by applying a concrete base and setting a wire mesh. 
  5.       Use additional concrete as a finishing touch as needed and pitch of the brick edges.  

Before Cement Crown Chimney Repair

before concrete crown chimney repair
The original crown was cracked and caused leaking into the fireplace. Another company came out to seal it which was the appropriate fix for the problem, but the product they used did not hold up. The sealant cracked and peeled and as a result, the leak came back, and the original crown got worse and needed to be rebuilt. Fortunatley, the case in the picture was not as bad as a previous job that required rebuilding the chimney. .

During Concrete Crown Chimney Repair

cement crown chimney repair half way
We removed the existing crown and cleaned off the surface thoroughly.

concrete chimney after bonding
Then we apply the base layer of concrete after brushing on the bonding agent to the surface area and then we set wire mesh on top to reinforce the crown.

After Concrete Crown Chimney Repair

After Concrete Crown Chimney Repair
Here is the new concrete crown. We also reset one brick on the corner and tuck pointed the 3rd course below the crown with a pitch to allow water to run off instead of sitting on the bricks. The roof was cleaned and washed afterwards. 

Stay tuned for part 3 in our chimney crown repair series: Floating Cast Chimney Crowns.  If you are in need of chimney repairs, please consider our company. 

Related crown repair articles

9 Common causes of chimney leaks

Chimney Repair- Chimney crown series part 3

Chimney repair – chimney crown series part 1

Chimney Repair: Chimney Crown Series -part 1

Crowns are a common source of chimney problems that result in chimney repairs.  From Silver Spring, MD to Annapolis and everywhere in between, chimney crowns are a cause for concern.  The is part 1 of a 3 part series concerning common chimney crown repairs.  

What is a chimney crown?

The chimney crown is the layer of concrete sitting on top of the last row of brick and its purpose is to shed water away from the chimney. It’s normally 3″-4″ inches thick and starts high around the flue liner then slopes down to the edge of the bricks. The chimney crown is the first line of defense for the masonry chimney, once the crown fails the chimneys become prone to leaking, and the masonry below will soon fail after. If caught early on the crown can be sealed to preserve it and prevent further damages. 

Chimney Crown Sealant

There are many different crown repair/sealant products available to us, and we’ve tried them all. Over the years, we’ve found that Crown Guard is a superior product for preserving and sealing the crown. 

Failed Crown Sealant

These two chimney crowns were sealed with another type of crown sealant, and both of them failed!

1) The first one was applied to a crown that needed to be rebuilt. The existing crown was so severely damaged that some areas were not even covering the bricks. The sealant started cracking (not suppose to happen) and peeling off. We rebuilt the concrete crown.

2) The second one was applied to a crown that was in fairly good shape. They sealed the crown in an attempt to stop a leak. As you can see the crown sealant is peeling off and the leak came back. We ended up rebuilding the concrete crown.  

Crown Guard

Crown Guard is applied when the crown is cracked but is still structurally intact.  The surface area of the current crown is first cleaned, then the Crown Guard is applied over the existing crown and covers all the surface areas of the crown.

Before Chimney Repair with Crown Guard

This chimney crown is cracked but is still structurally sound. Crown Guard is the appropriate fix for the situation.

After Chimney Repair with Crown Guard

Crown Guard is clear and can be applied with temperatures ranging from  -40 degrees to +140 degrees Fahrenheit. It won’t crack or peel like other crown repair/sealer products in the market, and it resists water immediately.

Leak Test After Crown Guard Application

crown guard leak test

As you can see here, the water is repelled and does not soak into the crown at all.

As a respected chimney repair company in Silver Spring, MD All Pro Chimney Service only uses the best products for sealing chimney crowns. 

Related crown repair articles

9 Common causes of chimney leaks

Chimney Repair- Chimney crown series part 3

Chimney repair – chimney crown series part 2




Questions for chimney repair companies about chimney inspections

chimney inspection

Every year homes across Washingon DC and its Maryland suburbs are bought and sold.  Regardless of whether the home is in Washington DC, Silver Spring, Annapolis, Columbia, MD or any other part of the Maryland suburbs, every home with a chimney must have a level 2 inspection prior to the sale being finalized. We previously discussed how 3 things to look for in a chimney repair company.  There are additional things to be asked when it comes to chimney inspections.  In this soot-free blog, we discuss some of the questions that you should ask any chimney repair company before hiring them for chimney inspections.

1. Are you licensed? 

Hiring a licensed chimney repair company to perform your chimney inspection is important.  Licensed chimney repair technicians are better equipped to access chimney problems.  There are many unlicensed chimney sweep companies in Maryland offering inspections.  Failure to hire a licensed chimney company could result in the home owner being liable for problems that are missed by the poorly trained inspector.  Such errors could result in fires that could result in property damage, injury and death.  Don’t take chances.  Only hire licensed chimney repair companies to provide your chimney inspection. 

2. Do you use video imaging during your inspections?

Taking video images of chimneys during inspections is the standard in the industry.  Unfortunately, some companies cut corners and fail to use video.  The best chimney Inspection companies take video recordings of their inspections and provide you with a detailed report.  The Chimney Safety Institute of America (CSIA) which is the standard bearer for the chimney industry recommends that video be used during level 2 inspections.  Level 2 inspections are a required part of selling any homes with chimneys.

3. How soon after the inspection will I get my inspection report?

The best companies send reports within 48 hours. However, some companies can take a week or longer to send the report to you. Long delays in receiving the report delays home sales and can cost home sellers the interest of a potential buyer. Quality reports in a timely manner helps you move on with your home sale. 

4. Is Your Company Insured? 

Insurance is important in case the company should damage your home, chimney, or property.  Picture this scenario: A home owner gets a level 2 chimney inspection and provides the report as part of the sale of the home.  A few months after the home is sold the house catches fire due to a preexisting problem with the chimney that the inspector missed.  At this point lawyers get involved.  Their goal is to sue whoever has the most money.  Typically, the costs would be handled by the chimney inspection company’s insurer.  What if the company does not have insurance?  Who do the lawyers go after?  The most likely person is the original home owner that failed to hire a reputable company to perform the inspection. 

5. Is your staff CSIA certified? 

The Chimney Safety Institute of America (CSIA) is a corner stone in home safety for chimney services, repair, and education. Not all companies hold a CSIA certification, nor do all workers. Some companies and employees learn on-the-job and hope for the best.  The value of CSIA certification is that you will have the confidence that your chimney inspector meets or exceeds the industry standards.  You can have the peace of mind of knowing that you have an accurate chimney inspection that will not expose you to liability. 

Anything that involves your chimney should be taken seriously.  Things missed during an inspection could result in fires.  Asking the right questions is an important part of selecting a chimney repair company to inspect your chimney. Of course, we recommend our company.