How to Repair Mortar in a Brick Wall
Repointing is a simple job, but it has to be done with care, using the right tools and the right materials
Even the most beautiful brickwork is just so much rubble without a bed of mortar to seal and hold it together. So when mortar starts cracking, receding, and falling out of the joints, it's time to chisel out the old stuff and trowel in the new, a process called repointing. This is a simple job, but it has to be done with care, using the right tools and the right materials to avoid damaging the brick and permanently compromising the integrity and appearance of the wall. For me, that means using hand tools and lime mortars similar to the ones masons employed 100 years ago.
Brick Repointing Overview
If your brick is 50 years old or less, you can probably repoint it safely with modern, portland cement–based mortar (although the guy doing the next repointing, who'll have to grind it out, may curse your decision). But if your house was built before World War II, the mortar is likely a mix of lime putty and sand, and you should try to match it. Otherwise, over time, as the soft old brick swells and shrinks against the rock-hard mortar, the bond between them will break, moisture will get trapped in the wall, and the brick faces will start popping off. Traditional lime mortar acts like a cushion, flexing with the brick's movement while allowing moisture to migrate easily out of the wall.
A restoration mason can analyze old mortar and make a compatible mix, or you can send mortar samples to companies such as Virginia Limeworks or U.S. Heritage and get a custom blend with the same color and characteristics. You can choose between hydraulic lime (shown), which comes in bags and hardens when it reacts with water, much like portland cement, and lime putty mortar, which comes in buckets and slowly hardens by reacting with carbon dioxide in the air.