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Why You Need to Repair Brick Mortar

Cracks and breaks in brick mortar may start small, but you should deal with them as soon as possible. Minor damage can grow larger and even small cracks or damaged areas can cause problems.

Bricks can loosen, decreasing the stability of the wall or structure.
Water can make its way into the surrounding mortar and brickwork, causing both to deteriorate.
Moisture can enter your home.
Cracks allow access to insects and other pests.
Gaps reduce energy efficiency and, in sub-freezing temperatures, can increase the risk of frozen pipes.

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Good to Know

The term pointing refers to the mortar joints between bricks. Tuckpointing or repointing is the process of replacing damaged mortar.

Causes of Brick Mortar Damage

Over time, the mortar that holds bricks in place and seals the brickwork can deteriorate and break down. Common causes for the damage include:

Natural Deterioration: Mortar isn’t as durable and long-lasting as brick. Depending on conditions, it can deteriorate over the course of 20 to 30 years.
Moisture: If moisture gets into the joints, it can damage the mortar. Cycles of freezing and thawing accelerate the damage.
Poor Maintenance: If you’re not promptly repairing mortar damage when you find it, the damage can spread.

If more than 1/4 inch of the mortar has deteriorated, if there are cracks in the mortar or if the mortar is breaking away from the brickwork, it’s time for repair.

When to Call a Pro for Mortar Repair

The steps below are tips for dealing with minor mortar damage. Some problems are more extensive or systemic and require a professional, including:

Poor Installation: Applying mortar with the wrong consistency or applying it incorrectly can keep it from curing correctly and making it vulnerable to damage. This may be a problem throughout the structure, requiring major repair.
A Settling Foundation: If a home foundation shifts or sinks it can damage both the brick and the mortar. Foundation cracks larger than 1/2 inch — especially if the foundation is bulging — need professional attention. Pay attention to the direction of foundation cracks. Cracks running left to right across the foundation need professional inspection. Those that run in multiple directions can suggest a significant structural problem. Don’t try to repair these yourself.

If you have any doubt about the cause or extent of the damage, contact a pro before beginning any work yourself.

Can You Put New Mortar Over Old Mortar?

If the existing mortar doesn’t predate the 1940s, you can apply new mortar into existing joints. First remove any damaged mortar as outlined below. Applying new mortar without dealing with the damage won’t create a lasting fix. It’ll be vulnerable to moisture and may require more extensive repairs in the future. If your home predates the 1940s you may need a special mortar made of sand and limestone putty.

Steps for Repairing Brick Mortar

Repairing minor damage to mortar or patching brick joints is relatively simple, though it takes some time and patience. Here are some mortar repair tips to consider before you begin the work:

You need temperatures to remain above 40 and below 90 degrees Fahrenheit until the mortar is fully hardened, so plan accordingly.
To make cleanup easier, place a drop cloth under the work area.
Cover plants in the work area as needed.
Close nearby windows and doors to keep dust out of your house.

General steps are below, but follow the instructions for the materials and tools you use and, if you discover the damage is extensive, stop and contact a pro.

Caution

Removing existing mortar will generate dust and debris. Preparing mortar mix will also generate dust. Wear safety glasses, work gloves and a respirator when working with the material.

Step-by-Step Mortar Repair

Thoroughly clear away the damaged material to a depth about 2 to 2-1/2 times the width of the joint. Remove damaged mortar from the horizontal bed joints and the vertical head joints. You want to have a stable base of good mortar the new mortar can adhere to.

For joints wider than 1/2 inch, chip out damaged mortar with a masonry utility chisel and hammer or engineering hammer.
On thinner joints, you may be able to use a grout saw with a carbide-coated blade.

Scrub away remaining loose material with a dry, stiff brush or wire brush.

Tip

Be careful to avoid damaging the bricks when you’re removing the mortar. The outer surface of a brick protects the inner core. Breaking this outer surface allows water into the core and can lead to more damage.

Remove your drop cloth, and using a garden hose and nozzle, lightly spray the work area. If you don’t properly moisten the bricks, they’ll draw moisture from the mortar you’re about to apply. The mortar won’t cure correctly and won’t last as long as it should.

Tip

You can wet the brick with a brush and a bucket of water instead of a hose. This will take longer than using a hose, but may prevent creating a wet, muddy workspace.

A person pouring water into a bucket of mortar mix.

Prepare mortar with water according to the product directions. Mix only what you can use in about an hour. In general, you want the mortar to have the consistency of peanut butter. It should be workable, but should stay on a trowel if you hold it upside down.

When you get the right consistency, let the mix sit. After 10 to 15 minutes a layer of water will form over it. Mix the water in again and the mortar will be ready to apply.

Tip

Type N mortar is a common, multi-purpose mortar for above-grade brick walls on the exterior of a home. If you have any questions about the right type of mortar for your application, talk with a Lowe’s associate or a pro.

If you’re tinting your mortar, check the tint instructions. You may need to blend it with the dry mortar mix before you add the water.

A person pressing new mortar into the joints between bricks.

Replace the drop cloth if needed. Use a trowel to collect some of the mortar. Hold the loaded trowel against one of the horizontal bed joints and use a thin tuckpointing trowel to press the mortar fully and tightly into the joints. Cut through the mortar with the tool to get rid of any bubbles or gaps in the material. Make sure the joints are full.

You can apply the mortar to the joints with the brick trowel and use the tuckpointing trowel to pack it, but you’ll likely have more excess mortar to clean up.

Once you’ve filled the bed joints for two or three bricks, use the same process to fill the vertical head joints. Clean away as much excess material as possible with your trowel.

Tip

Check the mortar instructions for how long the mixture remains workable. Mix new material as needed. Mortar that's lost too much moisture will not be as strong as it should be.

A person using a jointer to smooth and finish new brick mortar on a wall.

Check the mortar after about 20-30 minutes. Once it’s firm enough to hold a fingerprint, you can use a wet sponge to clean the excess mortar from the surrounding bricks.

Finish or tool the joints to create a clean look. Match your existing joints. Pull a jointer through the mortar for a concave finish or run a raker over it if you have flat joints. Be sure to clean up the vertical and horizontal intersections. Don’t wait too long to tool the mortar. It will harden and become difficult to finish.

Brush off any excess mortar before it hardens.

Tip

Keep the mortar and surrounding brick moist for about three days. This helps keep the mortar from drying too quickly so it can attain full strength. Use sheeting to protect the mortar from the elements until it fully hardens.

Frequently Asked Questions About Brick Mortar Repair

Use these quick answers to common mortar repair questions to plan your work.

How Do You Fill In Broken Mortar?

Use a hammer and chisel to remove all broken mortar to a depth 2 to 2-1/2 times the width of the joint. Moisten the surrounding mortar and brick. Apply new mortar to the joint, pressing it fully into the space and eliminating any air gaps. When the mortar has firmed enough to hold a fingerprint, use a finishing tool to create a flat or concave surface to match your existing mortar.

Will Fresh Mortar Stick to Dried Mortar?

As long as you’re following the mixing instructions, have cleared loose material and are applying the new mortar correctly, it should bind with the existing, dried mortar. Refer to the mortar instructions for application details and to see how long the mortar is usable after mixing. Mix only enough to use during that time. If the mortar dries out too much, it won’t bind properly and won’t create a strong joint.

What Is Mortar Filler?

The term mortar filler often refers to flexible acrylic sealant, epoxy or polyurethane foam that you can use to seal some cracks in mortar, concrete or other masonry products. You typically apply this crack filler using a squeeze bottle, a spray or a tube and caulk gun. Products and uses vary. Some fillers may be designed for small cracks (for example, 1/8- to 1/4-inch cracks) or specific materials.

What Is The Difference Between Cement And Mortar?

Mortar holds masonry — bricks, concrete blocks and stones — together. Cement is an ingredient of mortar. After you add water to a mortar mix, the cement hardens as it dries, binding with sand in the mix to give mortar its strength and binding to the masonry. In concrete, cement binds sand and gravel together to create slabs, driveways and foundations.

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How to Repair Brick Mortar