Chimney Crack Sealant: Uses, Types & How To Apply

Here, we’ll be discussing all chimney crack sealants.

Chimneys are venting structures that are generally built to last. However, even the best construction isn’t immune to deterioration.

Over time, chimneys begin to steadily deteriorate due to exposure to harsh weather conditions.

As a matter of fact, no man-made structure is built to last forever.

There are basically four types of chimney damage. They include regular wear & tear, moisture damage, latent defect, as well as a sudden event.

We’re more interested in the first which is regular wear and tear.

This is where chimney cracks belong to.

What Leads to Cracks in Chimney

Before we get into our discussion on chimney crack sealants, it’s important to mention the causes of these cracks.

What causes your chimney to crack? Several things do.

Such causes include moisture, improper construction, and wind tension.

  • Moisture

Moisture is the primary cause of chimney cracks.

This is even more problematic for an unprotected or capped chimney. When moisture gets absorbed into or gets between masonry, freeze-thaw cycles may occur which weaken the structure.

Here, moisture absorbed into mortar gets frozen in winter which leads to expansion. The reverse occurs when it thaws. This continuous cycle weakens your chimney structure with cracks developing.

A proper moisture sealant needs to be applied to prevent all of that from happening.

  • Improper Construction

Improper construction by inexperienced technicians creates a disaster waiting to happen. All construction defects eventually contribute to the weakening and cracking of the structure.

Corrective repairs may be extensive and require tearing down the entire chimney structure.

  • Wind Tension

Windy conditions can be quite strong.

This is especially true for areas with a lot of wind. The tension exerted on the chimney by strong winds is likely to result in cracks.

The Need for Chimney Sealants

Ordinarily, basic chimney wear and tear can be fixed with water repellent products.

Here, cracks are minute and not so visible. However, the use of chimney crack sealants becomes necessary when these cracks become larger.

As suggested by the name, chimney crack sealants help seal up or repair cracks of varying degrees. Basically, these sealants have elastomeric properties and are brushable on mortar joints.

Consider chimney crack sealants as paintable caulks.

When applied to cracks, sealants help keep out moisture from further penetration. These sealants are designed in such a way that moisture isn’t trapped when applied.

Moisture within chimney masonry can escape, thus eliminating future problems arising from freeze & thaw cycles.

Types of Chimney Crack Sealants

When it comes to chimney crack sealants, there are lots of brands available to choose from.

While this is true, not all are considered as being among the top brands. Now, being among the top brand doesn’t automatically translate to being the best.

It only means that such products are quite popular with use among technicians.

An argument could be made for that as being reliable enough, hence making these products preferable by chimney technicians.

Some of the top brands include ChimneyRX Masonry Fireplace Crack & Joint Sealant, and ChimneySaver Crack & Joint Sealant.

Let’s discuss these two brands of sealants to enable you better appreciate their functions.

  • ChimneyRX Masonry Fireplace Crack & Joint Sealant

This brushable elastomeric sealant product is used for all types of crack sealing jobs on chimneys. It’s used on the external surfaces of stone masonry units, concrete masonry, brick walls, and so on.

Because larger cracks are likely to appear on chimneys, this sealant is designed to fit both large and small cracks.

How large of a crack can be fixed with this sealant product? According to the manufacturer, cracks measuring around 1/8 inches wide can be repaired with this product.

Not only are these cracks fixed, but waterproof protection is also provided by this product.

As with most reliable sealant products, ChimneyRX Masonry Crack Sealant allows for the escape of moisture while preventing further absorption or infiltration of moisture.

Masonry joints are also held in place without the need for tuckpointing.

  • ChimneySaver Crack & Joint Sealant

This is another reliable chimney crack sealant product that helps fix cracks at different stages of development.

Now, it’s a fact that water repellents only do so much to prevent water infiltration. Where these become inadequate, ChimneySaver’s Crack and Joint Sealant get the job done.

It’s also a brushable product that will allow the escape of moisture while preventing the absorption of more. When applied to cracks, it leaves no significant changes to the looks of masonry bricks.

The only difference is a slightly glossy look behind.

One of the best features of this product is its 10 years warranty. This gives users added confidence with its use.

However, the manufacturer recommends storing the product under ideal temperature conditions to avoid solidifying. So, what’s the unsafe temperature limit?

Temperatures below 40 degrees F are likely to cause this crack sealant to solidify.

So, you should adhere to the use instructions after purchase.

Does it mean No Cracks Will Appear after Treatment?

Most people will assume that the warranty given by the manufacturer will hold for as long as it lasts.

However, the reality is quite different. This isn’t to say that the warranties given are wrong.

Rather, certain conditions (ideal) have to be met for the product to last that long.

Having applied your chimney crack sealant, you might discover that other areas get cracked. These areas may not have been previously treated.

There’s no way the warranty is voided when such surfaces had not previously been treated.

Your best bet is to have the entire chimney surface treated as a preventive measure against future cracks. However, this should only be performed at the advice of a chimney technician.

Applying Chimney Crack Sealants

These products come with use instructions from the manufacturer. Plus, there’s a need to have a trained technician perform all such responsibilities.

Trained and experienced technicians know how best to carry out a crack sealing job on your chimney.

Having these technicians get the job done helps a great deal in keeping your chimney in great condition. The crack is properly sealed with no chance of moisture penetration.

Chimney crack sealants are the perfect response to cracks on chimneys. You’ll need to have pros perform this procedure to find out if there are other issues beyond cracks.

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