How to Fix Brick Mortar: A Detailed 6-Step Guide

Although pointing is an easy job, it requires care and the use of the right tools. Without mortar to hold it together, even the most exquisite brickwork can be just as much rubble.

What is Mortar Repointing?

Repointing is when mortar cracks, recedes or falls out of joints. Although this is an easy job, it requires care. You must use the right tools and materials to prevent brick damage and permanent wall defects. This means we use hand tools and lime mortars that are similar to those used by masons 100 years ago.

Mortar over Old Mortar?

You can repoint bricks older than 50 years with modern portland cement-based mortar. However, the guy who will be repointing your next house may not approve of your choice. If your house was built prior to World War II, it is likely that the mortar contains a mixture of lime putty, and sand, so you will need to match it.

If the mortar is not matched, the bond between the brick and rock-hard mortar will eventually break. The bricks will begin to pop off as moisture gets trapped in the walls. Lime mortar is a traditional cushion that flexes with the brick’s movement and allows moisture to move freely out of the wall.

An experienced restoration mason will analyze your mortar to create a compatible mixture. Or, you can send samples of mortar to the U.S. You can also request a blend that is identical to Heritage. Hydraulic lime comes in bags, hardens with water, and is similar to portland cement. Lime putty mortar comes in buckets, hardens slowly with carbon dioxide in the air, and comes in bags.

6 Steps to Mortar Bricks

Step 1

Remove the Bed Joints

To remove horizontal joints, scrape them to a depth of at minimum 3/4 inches. Joints that are more than 1/2 inch wide must be dug to a depth of at least 3/4 inch. These 1/4-inch “butter joints” can be cut with a carbide-tipped grout saw. For larger joints, a cold chisel or an engineer’s tool can be used. Avoid electric angle grinders. They can easily cut through bricks if you aren’t skilled in using them.

Step 2

Clear out the Head Joints

Dig out the vertical joints after removing three to four courses of mortar for the bed-joint mortar. Pay attention not to strike the brick edges below or above. This is where the mortar is removed by tapping a 5-in-1 hammer on a painter’s knife.

Step 3

Wash Down The Wall

With a stiff-bristled toothbrush, remove all crumbly material. Next, check that your tuckpointing trowel blade fits into the joint. You can grind the blade down with an abrasive tool if it is too long. Mist the brick with water until it is completely damp. This is important because dry materials can suck moisture from the mortar, preventing it from curing properly. Do not fill the joints until the next day.

Step 4

Mix the Mortar

Again, mist the brick. Follow the instructions on the bag to stir the water into the dry mixture until it becomes a peanut butter-like consistency and sticks to a trowel. Allow the mixture to rest for 15 minutes until it forms a thin layer of water. Mix the water back into the mixture. Now the mortar is ready for use. It will remain usable for eight hours. You can “retemper,” it if it becomes too dry during that time by adding water occasionally.

Step 5

Fill the Joints

A dollop of mortar should be poured onto a brick trowel, hawk, or another flat surface. The mortar should be held up with a bed joint and pushed against the back with the tuckpointing trowel. After removing any voids, make a few passes along the trowel’s edge to fill them in. Then add more mortar until you have filled the joint. After you have completed three to four courses of bed joints, fill the head joints. Final step: Smoothen and compact all mortar using the trowel’s flat surface. Finally, remove any mortar from the brick.

Step 6

Brush the Wall

Brush diagonally across the mortar to remove any mortar crumbs. The fresh mortar can be pulled out by brushing in line with joints. Next, carefully remove any mortar residue from the brick faces. Use a tarp to cover the mortar joints against the sun, wind, or rain for the next three days. Give the wall a misting every day to keep it moist.

Frequently Asked Questions

1. What is Mortar Repointing?
   • Mortar repointing involves repairing and renewing the mortar joints between bricks. This maintenance process is essential for preserving the structural integrity and aesthetic of brick constructions, especially as mortar ages and deteriorates.
2. Can I Use Modern Mortar on Older Brick Structures?
   • For brick structures older than 50 years, especially those built before World War II, it’s recommended to use a lime putty and sand mixture similar to the original mortar rather than modern portland cement-based mortar. This ensures compatibility and prevents damage to the bricks.
3. Why Should I Avoid Using Electric Angle Grinders for Repointing?
   • Electric angle grinders can be too aggressive for repointing, potentially damaging the bricks if not handled with precision. Hand tools are preferred for their control and gentleness on the historic masonry.
4. How Deep Should I Remove the Old Mortar?
   • Generally, old mortar should be removed to a depth of at least 3/4 inch for bed joints, or deeper if the joint width requires. This ensures a sufficient depth for the new mortar to bond effectively and provide structural stability.
5. What Should I Do if the Tuckpointing Trowel Doesn’t Fit the Joints?
   • If the tuckpointing trowel is too large to fit into the joints, you can grind down the blade with an abrasive tool to reduce its width. This customization allows the trowel to fit properly and aids in effective mortar application.
6. How Do I Ensure the New Mortar Cures Properly?
   • After repointing, it’s crucial to keep the new mortar moist for several days. Cover the repointed area with a tarp to protect it from sun and wind, and mist the wall daily to maintain adequate moisture levels. This helps the mortar cure slowly and gain strength.