Crumbling Brick Repair Guide

wall of crumbling old brick
  • 4-8 hours
  • Intermediate
  • 30-200
What You'll Need
Safety goggles
Pressure washer
Premixed brick mortar
Wire brush
Mortar strike

Brick repair is a simple, straightforward procedure that does not require the skills of a professional brickmason, despite what you might have thought. Brick masonry has an average life span of about 100 years, but the mortar joints will last only about half as long, which is why older brick walls will sometimes require a repair process known as repointing.

Loose or crumbling mortar and cracked or splitting mortar joints are caused by natural weathering or settling in the foundation. Noticing this type of damage and repairing it quickly is important, as this type of damage indicates deterioration in the brick wall and susceptibility to water penetration.

Repointing involves removing all unstable mortar within the vertical and horizontal joints and then applying a layer of new mortar to the cleaned joint.

Step 1 - Prepare the Surface

Thoroughly clean the brick wall surface with a pressure washer before you repoint any joints. This will also help remove some of the loose mortar.

Step 2 - Remove All Loose and Crumbling Mortar From the Joints

Wear safety goggles during this step. Begin by chiseling out the weakened mortar down to a depth of 1/2 inch. Alternatively, you could use a heavy wire brush or grinding tool. Take care not to damage or scar the face of the brick; focus only on mortar joints that have become eroded or brittle need to be repaired. When the repointing is done, you can paint a commercial bonding agent onto the cleaned joints to ensure a solid bond.

Step 3 - Apply the New Mortar

Use pre-mixed mortar designed specifically for brick work. Before mixing a full batch, mix a small amount of mortar and let it dry to determine its final color. If it doesn’t match the existing mortar, coloring agents are also available.

Apply the new mortar to the cleaned-out joints, first the vertical and then the horizontal joints, filling each as you go. Use a sharp trowel to pack each joint with mortar, leaving no spaces or air-pockets.

Step 4 - The Finishing Process

The joints should be finished to match the shape of the existing mortar joints. The tip of the trowel can be used to give a V-shaped joint; a mortar strike, a nail head or even a finger can produce a rounded, concave joint. Keep the newly applied mortar wet or damp for a few days to prevent it from drying too quickly. When the masonry repair is completed, any excess mortar can be cleaned from the wall by using muriatic acid and/or a stiff brush.

Occasionally, whole bricks will become loose or be missing and will have to be replaced. Select replacement bricks to match the size and color of the existing brick as closely as possible, making the repair work undetectable.