Fire Brick Repair – Quick Tips to Fix Cracks in Bricks and Mortar

When you see your fireplace hissing noise, your domestic or oven chimney is exhausting dense clouds of smoke, or you find droplets of creosote dripping in the fire area, this is literally a red alert for you.

Fire Brick Repair

The Red alert for due maintenance of your fireplace! Remember, your fireplaces have to bear extreme environmental conditions. So, cracking mortar and bricks is normal, especially in moist environments.

Since firebricks are one of the most pivotal components of fireplaces, you only have to assume whether cracks coming in your fireplace structure are concerning? Is there really a need for fireplace brick replacement? In any case, the cracks in fireplace brick or mortar need a fix; how to fix the fireplace without disturbing the structure?

This is the menu for today, let’s join us;

Fireplace Brick Repair – The Right Methodology for Repairing the Cracked Bricks:

Pinpoint it! Your fireplace is your baby. It needs ultimate care, from building it from scratch to maintaining a servicing fireplace. People make mistakes. That’s why they face mortar or brick cracks.

For example, when you start building a fireplace, more specifically the chimney, the bricks, before getting cemented with mortar, need to be treated with water. Likewise, when you finish building up your fireplace, it also needs water treatment as the cement mortar dries and shrinks.

Fireplace Brick Repair

The water keeps the balance of moisture level during the drying process. It helps the structure to get concrete strength without getting cracked.

Skipping the water phase results in cracks in fireplace bricks and mortar that deteriorate further, turning into a vulnerability. Similarly, there are also many steps to be taken care of to avoid cracks in fireplace bricks.

Now, I know, this may not be your point of interest so let’s jump onto the steps needed in fixing the fireplace;

How to Repair Cracked Brick:

First thing first, do assume what you are going to fix? A broken/cracked firebrick or cracked mortar? For a crack in fireplace bricks, this is how you do it;

How to Repair Cracked Brick

Let’s assume first from what type of cracks bricks have been hurt with. If it has significant cracks or is broken into pieces, you need to replace the fireplace brick as a whole. Otherwise, minor to moderate cracks need to be fixed, there is no need for replacement and this is how it should be fixed;

  1. The damaged brick first needs a cleanup from dust, grease, oil, and other build-ups due to smoke and other particles.
  2. Also, vacuum or soak all the residue between cracks.
  3. Now, if the cracks are major, you can push the mortar through a trawler and remove all the excess mortar.
  4. If the cracks are minor and the trowel can’t reach the depth of the crack, use a nozzle gun to push the cement mixture into the cracks.
  5. Let it dry for 3-4 days as per the weather conditions. If it’s humid, I would suggest you wait for at least 7 days. Otherwise, in sunny and hot weather, 2-3 days are fine
  6. Heat the fireplace gradually to resist the cracks and breakage of bricks again.

How to do Fireplace Mortar Repair?

Now, this was all about repairing cracked bricks; mortar is another thing that acts like a barrier against higher temperatures. In fact, mortar is a substance that makes the bricks gel with each other to save the outer walls from damage.

How to do Fireplace Mortar Repair

Yet, continuous extreme temperatures cause contraction and expansion that deteriorate the mortar. So, to repair the mortar cracks, follow this step line;

  1. Inspect the points deeply where the mortar has been cracked and joints have been loosened.
  2. Scrape out the damaged mortar with a putty knife. Dig out the affected mortar from 0.5 to 1 inch so the new mortar paste will perfectly gel with the existing one.
  3. Brush out the residue between vacant spaces or joints between the bricks; vacuuming through a nozzle is a better option.
  4. Now, spray or brush the scrapped spaces with water so the new mortar finds its abrasiveness. Water acts like a bonding agent between bricks and mortar.
  5. Now inject the mortar paste with a trawler into the vacant spaces. You can also use caulking agents instead of mortar. Yet, I prefer mortar more than caulk.
  6. Cleanse off the excessive mortar and let it dry for 2-3 days.

How to Fix Cracked Fireplace Panels:

If you are a guy who doesn’t love to make your hand and place dirty with DIY fireplaces project, refractory fireplace or panels are a cost-effective and ready-to-go solution for your house.

Yet, do you escape from the cracks in this regard? Don’t expect that!

Your fireplace panels can also face cracks, and for that purpose, the better move is to call your panel’s vendor and take action as per your vendor’s recommendation.

How to Fix Cracked Fireplace Panels

However, when is the real need to call your vendor for the repair service? When is the absolute need for fireplace crack repair or replacement?

Don’t make guesses, Chimney Safety Institute of America (CSIA) gives unambiguous guidelines about the levels of cracks. Most people take hairline cracks in brick panels as worrisome. Yet, according to CSIA guidelines, if the cracks aren’t expanding after every firing session and have a width under 1/16 inches, you can take a breath of relief.

Nonetheless, expansion and contraction happen when fireplaces come under extreme temperatures. If that situation widens the cracks of the bricks, you need to call the emergency. As refractory fireplace panels are pre-built, CSIA also recommends you don’t treat these without any professional assistance.

Therefore, first, assume the behavior of any hairline or usual crack, map the width, then take further action.

Why Time-Time Inspection of Your Fireplace is Necessary: Steps to Avoid Cracks

Unfortunately, facing the cracks in fireplace bricks is an obvious circumstance. Whether you face it after months or after years or decades, you surely need to prepare yourself for that and have strict eyes on your fireplaces.

But by saying that, no one wants a cracked firebox in the shortest time after installing a fresh fireplace or fixing the fireplace. Indeed, you can extend the life of your fire areas. So, here are some steps to vastly prevent the need for any kind of fireplace brick repair and replacement. You can check the list of best outdoor brick pizza ovens I have reviewed.

Timely Maintenance Is the Key: 

Apart from cracks and Spalling, creosote is the most dangerous thing that leads to a potential fire hazard.

Timely Maintenance Is the Key

Bear in mind, firebricks are built to last even 100 years. Yet, moisture can kill its life and can break it into months. When creosote develops, a combination of greasy substance, smoke particles, and wood ashes creates moisture within the fireplace lining.

When you heat the fireplace, there is an intense thermal shock that potentially leads to the cracking and breaking of bricks. So to avoid these circumstances, don’t let creosote develop into 3rd stage. Clean your fireplace from time to time.   

Save Your Fireplace from Water Infiltration at Any Cost: 

Water is the real enemy of your fireplace. For that purpose, you have to block all possible loopholes from where water can do the damage. For example, your chimney is the biggest hole from where water can drip down to your fireplace.

Save Your Fireplace from Water Infiltration at Any Cost

So, the design of your chimney is a very important factor in the life of your fireplace. Cover your chimney with a perfectly designed cap to protect the masonry or refractory fireplaces from water.

Also, repair the deteriorated mortar cracks and, as it can also be a passage for water to enter the firebox. In fact, water leakage is much more dangerous as it converts into moisture, and you know all the later story. So, blocking water infiltration is the key to saving your fireplaces from cracks.

Don’t Use Water As a Cleaning Agent:

Cleaning and Maintaining your fireplace is good, but don’t ruin your efforts, resources, and time by using water and other liquid solutions as cleaning agents for bricks. This can add moisture, and again, the remaining story is the same.

Don’t Use Water As a Cleaning Agent

Instead, always use specialized scraper tools to peel off the residue, dry cloth to clean, and caulk to fill any deteriorating spot. This will save you considerable time from fireplace mortar and brick cracks.  


How Long Should Fire Bricks Last?

Fire bricks last for several years. But this is not just enough to say and expect the firebricks to run from year to year. Immense care and timely maintenance keep these bricks to go finely for over a decade. Yet, if you don’t adopt the proper maintenance procedures, they may get damaged in months.

Do you need to replace cracked fire bricks?

According to CSIA, if cracks are more expansive than 1/16 inch, then you need to fix or replace the brick. However, if you are concerned about the cracks, which are as thin as a hair thread, they are better to ignore. But for wider cracks, it’s always advised to replace the fire bricks.

Do fire bricks wear out?

Yes, fire bricks wear out. Especially when there is a thermal shock, or they haven’t been maintained for ages. These are hard building materials but sensitive to moisture and carelessness.

The Bottom Line:

So, how to repair fireplace bricks? There are two Scenarios; repair or replacement. You have to critically observe what types of cracks are there in your fireplace. Thin cracks should mostly get ignored; however, CSIA considers cracks wider than 1/16th inch should be taken seriously. So, whether you repair cracked bricks or perform an entire fireplace brick replacement, this article tells you the appropriate ways of doing that.

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