Maybe we can blame it on the Big Bad Wolf, but we often think of brick buildings as ultra durable, long-lasting structures designed to withstand anything. And while that may be true to a point, they’ll really only last if they’re taken care of. This means repointing the brick when the mortar starts to deteriorate.
While the material itself may seem simple (hint: mortar mix isn’t always the answer), there are actually a few things to know about how to repoint brick. You need to know when to repoint, how much old mortar to remove, which new mortar to use, and the overall process. Here’s a helpful guide to break it all down.
When to Repoint
Mortar joints are designed to last for decades—20 to 30 years is a minimum, with most mortar joints lasting much longer. However, if the joints crack, trap moisture, and freeze, they’ll start to deteriorate, compounding the issue. Common tipoffs that a brick surface needs repointing include crumbling loose mortar (missing more than ¼-inch of the original mortar), excessive cracking, dampness on walls inside the building, and spalling or crumbling bricks. When you notice any of these signs, it’s time to repoint.
A good rule of thumb is if the mortar has eroded deeper than twice the width of the joint, you should repoint.
Pro Tip: This Old House mason Mark McCullough explains why deteriorated mortar lets water in: “In my experience, this happens when you don’t properly wet the surrounding brick before applying the mortar. If you skip that step, the moisture gets sucked out of the mortar as it dries and you’re left with what we call dusty mortar.”
You Need the Right Mortar
Choosing the right type of mortar for the brick is just as important as the technique used. Homes that were built before the 1930s typically use a softer brick and require a lime-based mortar. These mortar joints are durable and long-lasting. They’re flexible and even self-healing to a certain extent. Using a modern mortar mix on a soft brick will often result in brick damage, such as cracking, crumbling, and other issues. If your home was built before the 1930s, use a lime-based mortar to be safe.
However, if your home was built after the 1930s, opt for a cement-based mixture, which is much harder and less forgiving.
Pro Tip: This Old House mason Mark McCullough explains the difference between the two most common mortar types: “Type S—think strength. So elevator shafts, stair shafts, retaining wall, foundation. Type N is what we strictly use for brick work. It gives a little bit of movability to the brick because everything’s a natural material, don’t forget.”
Choose the Right Conditions for Repointing
Like most masonry work, you’ll need optimal conditions for repointing brick. Ideally, wait for a week of mild temperatures for this project—no warmer than 90 degrees during the day and no cooler than 40 degrees at night. High temperatures will prevent the mortar from curing properly before it dries, while cold temperatures will yield a brittle mortar.
Regardless of the conditions, you’ll need to keep the mortar damp for at least three days to prevent drying before it cures. A light mist from a garden hose will do the trick but avoid a direct stream that might wash away uncured mortar from the joint.
How to Repoint Brick
You will need:
Protective glasses
Dust mask
Cold chisel
Masonry hammer
Grinder with a diamond wheel (optional)
Stiff bristled brush
Spray bottle filled with water
Bucket or mason’s tub
Mortar mix (appropriate to age of the brick)
Bricklayer’s trowel
Tuckpointing trowel
Pointing trowel or jointing trowel
1. Inspect the mortar joints around the home to pinpoint which areas need replacing. You may not need to repoint the entire home if the existing mortar is in good shape.
2. Match the mortar type to the age of the building and the color of the existing mortar. If the home was built before 1930 but the mortar isn’t white, it is probably still lime-based but has a coloring agent added to it.
3. Put on protective glasses and a dust mask as a safety precaution. Then, use the cold chisel and masonry hammer to remove the old mortar. Chip enough mortar away until the joint is ¾” to 1” deep. Be careful not to chip the bricks’ surfaces or edges.
Note: You can use a grinder with a diamond wheel for the horizontal joints. However, this may make it easy to damage the brick, so a chisel may be the best way to go.
4. Clean the joints out by brushing them with a stiff-bristled brush.
5. Dampen the surface of the brick with a spray bottle filled with water. This will prevent the brick from pulling the moisture from the mortar too quickly.
6. In a bucket or mason’s tub, mix the chosen mortar mix until it’s the consistency of oatmeal.
7. Scoop some mortar onto the bricklayer’s trowel, hold the trowel against the brick below the joint, and use the tuckpointing trowel to pack it in between the bricks. Fill the bed joints first (the horizontal joints) before moving to the head joints (the vertical joints).
The goal is not to pack the entire joint at once but to apply 3 or 4 layers and compact them tightly each time. This will prevent air pockets from forming, ensuring the mortar is as stable and sound as possible.
8. Once the mortar starts to firm up, tool it to match the existing mortar joint profile. This may require a pointing towel, a jointing tool, or several other masonry trowels and techniques, depending on the existing joints. Lightly brush the surface with a stiff-bristle brush to blend the texture and remove excess mortar.
9. Keep the area around the repair moist for at least three days by misting it with a garden hose or sprayer.
Pro Tip: Why go so deep? As TThis Old House masonry experts explain, mortar does not stick to mortar—it sticks to brick. That’s why you need to expose at least three quarters of an inch of brick surface on each side of the joint. The more brick that’s exposed, the stronger the bond will be when you pack in the new mortar.
Should You DIY Brick Repointing?
Once you know what goes into brick repointing and choosing the right mortar, you can handle most small repointing projects on your own. If it’s a small area and easily accessible, repointing isn’t too difficult a job if you’re comfortable with hand tools and have basic DIY skills.
However, there are points (no pun intended) when hiring a professional is the best move. Performing masonry work on a high wall or a chimney is strenuous, which can then become dangerous. Also, if you’re seeing structural cracks such as stair-step cracks or vertical cracking around windows, calling a pro is the best move.
Pro Tip: This Old House mason Mark cautions against rushing the chiseling step: “One of the most important things is we want you to stay off the edge of that brick with your chisel. Just like this—you sneak it in, hammer.” Taking care to angle the chisel into the joint, rather than against the brick face, prevents costly chips and spalling.
Brick Repointing Costs
The cost to repoint brick is typically between $3 and $20 per square foot, depending on several factors. If the brick is very old and the mortar can’t be removed with a grinder for fear of damage, it will cost more. Plus, if there is significant damage to the brick already, the cost will be higher. If scaffolding is necessary, expect to pay more as well.
Done Right, Your New Mortar Will Last Decades
If you’ve successfully repointed your brick, expect to get at least another 20 to 30 years from those joints. Take your time to find the right mortar, don’t rush the project, and use the proper techniques to ensure a job well done, without paying a ton of money to masonry contractors.
