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How to Repair a Crack in Brick Wall (DIY)

A collage of illustrations on how to repair a crack in a brick wall.

If you need to repair a minor crack in a wall to flip a house or because you want to repair an unsightly crack, there is no need to get an expensive contractor out or to break away parts of the wall to repair it. A very simple and effective method of filling and blending in the crack can be used.

Repair a crack in a brick wall by filling the crack with concrete and mortar filler and sealant. Cut the filler nozzle, pump filler into the crack, and smooth it with your finger. Next, wipe off the excess filler with a rag, clean the wall, and smooth the area with a wet finger.

A crack in a brick wall can be unsightly. Provided there is no structural damage to the wall, it is a repair that most DIY enthusiasts can do themselves. Follow the simple steps below to have your wall look as good as new in no time at all. Do remember, though, that you will need to wait for the filler to dry before you can paint over it or do any other repairs to the wall.

How to Repair a Crack in Brick Wall - Step 2: Pump the Filler Into the Crack

How to Repair a Crack in Brick Wall

Materials

Instructions

Before beginning any crack repair work, get a contractor or registered professional to inspect the crack and the wall to ensure it is not structurally damaged. Speak to your local authorities to check who the correct person or body is to sign off on this.

Structural damage will need a far more extensive repair than a patch. Also, if the crack is structural, it will return after a month or two if it is just patched.

Step 1: Prepare the Nozzle of the Concrete & Mortar Filler

How to Repair a Crack in Brick Wall - Step 1: Prepare the Nozzle of the Concrete & Mortar Filler

Begin by using the cutting tool to slice the end off the concrete and mortar filler nozzle. In some cases, you will need to unscrew the nozzle first, cut or peel open the opening on the tube to allow the filler to come out, and then replace the nozzle so it can flow down the nozzle in a controlled and directed way.

Be careful not to cut yourself when preparing the nozzle. Cut away from your body on a hard surface while gripping the tube firmly in your non-dominant hand. While the nozzle is plastic, it will give some resistance but may cut quickly after initial resistance.

Place the tube into the caulk gun by releasing the pressure clip at the back, pulling the pressure plate to the handle end, and inserting the tube. Give the handle a few gentle pumps until the mortar comes out at the end of the nozzle. Your concrete and mortar filler is ready to use.

Top Tip: Cut the nozzle of the concrete mix tube the same size as the crack in the wall. That way, the exact amount of concrete mix will fill the hole without overfilling or underfilling.

Step 2: Pump the Filler Into the Crack

How to Repair a Crack in Brick Wall - Step 2: Pump the Filler Into the Crack

Place the open end of the nozzle directly on the crack and pump the concrete and mortar filler into the crack. Place the tip of the nozzle over the crack so you will get the most filler into the crack at once. 

Using your dominant hand to hold the nozzle end of the caulk gun against the wall, guide the nozzle along the entire crack length.

Applying pressure where the nozzle's opening meets the crack will force filler deeper into the crack. There should be no gap between the nozzle and the wall at all.

Move slowly along the length of the crack, ensuring there is enough filler going into the crack before moving the nozzle along. Going over the crack with filler a second time can be messier than just doing it once, so you want to be slow and sure at this step.

Top Tip: If you stop pumping filler into the crack, release the pressure on the mortar tube before you put it down by pushing the release clip at the back of the caulk gun. The filler should stop coming out of the nozzle, and it will not leak while you are doing step 3.

Step 3: Smooth the Filler With Your Finger

How to Repair a Crack in Brick Wall - Step 3: Smooth the Filler With Your Finger

Using your index or ring finger, remove excess filler with your finger. Wipe downwards and sideways with the tip of your finger, being careful not to spread the filler onto the bricks but keep it in the space between the two bricks.

Push downwards and into the crack with your finger as you go so that the filler fills as deep into the crack as possible. The deeper the filler goes into the crack, the less likely the crack is to reappear with further settling.

Do this slowly and methodically for the entire length of the crack.

Top Tip: Use any extra filler you collect on your finger to fill areas where there is not enough. 

Note: It is recommended that you use gloves for this step, but some people prefer to do it with a bare finger as gloves decrease the ability to feel what you are doing.

Step 4: Wipe Off Excess Filler With a Rag

How to Repair a Crack in Brick Wall - Step 4: Wipe Off Excess Filler With a Rag

Take as much time as needed to complete this step, as it will make the difference between a professional finish and one that shows the filler.

Using a clean, wet rag, wipe the edges of the bricks and the areas surrounding the crack to smooth the filler to the same level as between all the other bricks.

Where necessary, wipe and clean bricks that have gotten filler on them. If the bricks are porous, ensure to wipe as much filler off as possible because when the filler dries, it may discolor the brick.

Top Tip: Turn and rotate the wet rag after every wipe, ensuring the area of the cloth is clean when you wipe so that it doesn't spread the filler onto the bricks. Rinse the rag regularly so that it is clean on every wipe.

Note: If the crack runs through a brick, use your discretion on whether it should be filled in with the rest of the crack. If the crack is not too wide, you can fill in the mortar areas around it and leave the brick crack open without it looking out of place.

Step 5: Wet and Smooth the Filler With Your Finger

The final step is to smooth the filled-in area with your finger so that the finish of the wet filler matches the dry areas surrounding it.

To do this, wet your finger, so it runs easily over the surface of the wet filler, smoothing the edges and the top of the wet filler. Go over the whole crack multiple times until it is perfect.

Leave the filler to dry for 24 hours or as recommended on the filler tube.

Check the filled-in crack the next day, depending on how wide the crack is. In some cases, the filler will have indented as it dried. If this has happened, spread a thin layer of filler over the filled-in area and smooth and clean it using steps 1-4 again. 

Leave the filled-in crack to dry. The filler should dry to the same color as the surrounding mortar, and you should not be able to tell there was a crack there, to begin with.

Top Tip: Use warm water on your finger and rag.

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Resource:

Crack in Brick Mortar Repair *Quick and Easy DIY*!

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