Summer is the perfect time to take a look at your chimney and look for any damages. Since the chimney won’t be fired up in the summer, you can get away with some types of repairs during this time. However, if there are leaks, which cracks cause, you should consider chimney repair sooner. Below are the different types of cracks you can see in a chimney.

Horizontal Cracks

Horizontal cracks, as the name suggests, are the cracks that run from the left to the right of the entire chimney structure. They can occur because of a plethora of reasons, the main ones being pressurized chimneys because of obstructions and movement in the chimney.

These cracks can also lead to spalling of the bricks and that’s very dangerous if it’s not dealt with soon. Horizontal cracks need to be fixed because the stability of the chimney is at risk and you don’t want it to fall apart at any moment.

The best way to go about this is to reinforce the cracks in the chimney with metal joints. These joints are applied vertically to hold the chimney in place. Sometimes, even filling the cracks is a good idea, but you need to stabilize the structure before doing anything else, otherwise the chimney might be at risk of collapsing.

Vertical Cracks

Vertical cracks occur along the length of the chimney. You can see the cracks in the chimney from the top to the bottom of the structure. The main reason for vertical cracks in the chimney is because of weather damage and movement of the chimney, which is also something that needs to be addressed.

Since the main cause of these cracks is water damage, the immediate remedial action is to waterproof the chimney entirely. This is done by applying a waterproof sealant all over the chimney after filling in the cracks.

As bricks are not waterproof and have pores in them that can let water in, it’s crucial to seal the structure so that water can bead on top of the sealed surface or flow down from the surface. If the cracks are very deep, then you need to have the bricks replaced and that can take a bit of time as well.

Stair Step Cracks

These cracks have a very unique shape and they can be seen in between the chimney bricks. Stair step cracks are cracks in the form of literal stairs. They are found in between the bricks and mortar joints. Stair step cracks are diagonally spread throughout the chimney structure and they can be caused by any sort of structural or foundation damage.

These cracks, once formed, can spread quickly and you need to fix them before they damage the entire chimney. To fix these cracks, helical bars are inserted in the mortar joints of the structure to add stability and strength to the chimney.

If that’s not working, then you’re left with the only viable option and that’s to repair the chimney structure altogether. You will need to build the chimney from the roof to the top to ensure that the structure is sturdy and that there aren’t any other major issues.

Crown Cracks

The chimney crown is the topmost part of the chimney where the cover is usually present. This part can also get cracked and cracks present on the crown are known as crown cracks. The main cause of these cracks is the absence of a chimney cap that protects it from weather damage, animals crawling inside, etc.

The crown of the chimney is a really important part of the entire assembly, because if the crown is damaged, then it can let the external agents in and cause even more problems like cracked flue liner. So, if you notice cracks, schedule a professional chimney inspection Upper Marlboro.

The best way to fix chimney crown cracks is to fill them up and apply a crown sealant, which is like a regular chimney sealant, but more heavy-duty and meant for rough weather conditions. This sealant waterproofs the crown of the chimney so that water or moisture can’t damage anything on top.

Common Causes Of Chimney Cracks

Now that you know what the different types of cracks in a chimney are, here are some of the most common causes of why they occur.

Weather Damage

First things first, weather is the main culprit in damaging the chimney and cracking it. Rain, thunder, wind, and extreme sunlight exposure can over time damage the chimney, and small cracks can form on the surface of the chimney. These cracks can later get bigger and deeper and they can damage the chimney to an irreversible extent.

Structural Damage

Chimneys aren’t meant to last forever. There may come a time when a chimney, even though you’ve repaired it time and time again, just can’t take any more damage and it will collapse and crack. The settling of the chimney on the roof can get disturbed and it can cause the chimney to crack from almost all sides.

This is a very common chimney problem and it occurs mostly in older constructions even though you’ve properly maintained them every single time. This is something that calls for rebuilding the chimney.

Impact Damage

When the weather is bad, things can move about outside with no sense of direction. Especially during turbulent winds and thunderstorms, there are times when small rocks, and even trees, can crash down onto the roof. In this scenario, your chimney can also be under a lot of threat.

Cracks and fissures are the preliminary damage and ultimately it can lead to the entire chimney falling or breaking apart completely. This is dangerous and you need to get to the bottom of this before things get out of hand and irreversible damage is done.

Poor Construction

A new chimney can also give you a hard time, especially if not built professionally. If your chimney was built by amateurs, then mentally prepare yourself for the consequences that follow. Improper chimney building can also lead to premature cracks and fissures and it’s really hard to deal with, especially if you’ve just had the chimney built.

It’s frustrating, but the best thing you can do to fix this is to get the chimney torn apart and make a new one, and this time you need to be careful because you need professionals for this job. So, always be vigilant when you’re hiring someone.

Water Damage

Water is also another culprit that can lead to cracks in the chimney. Whether it’s rain or just moisture in the air, it can penetrate the chimney and cause even more issues than before. Water eats up the bricks and damages the mortar, which is the core thing that keeps everything glued together in a chimney.

Once these things are damaged, the chimney can start to crack and if they go unnoticed, the cracks can get bigger and there will come a point of no return for the poor chimney.


Different cracks can lead to different intensities of damage and that’s something you need to be aware of. If you want your chimney to work perfectly in winter, consult chimney contractors Columbia MD for repair whenever you notice cracks or leaks.