How to Repoint a Chimney in 9 Steps

In the worst cases, you may already see crumbling mortar and bricks even from afar. But if you suspect it’s time to repoint your chimney but aren’t sure of the true condition of the mortar, you’ll need a ladder and a pointing chisel or screwdriver to test the condition of the mortar.

Put pressure on the mortar and see if it crumbles easily under the pressure of the tool. You can also do a visual inspection to see if there’s any erosion of mortar from the surface of the bricks greater than 6 millimeters.

Alternatively, you can hire a chimney inspector near you to assess the condition of your mortar and identify any other potential chimney problems.

Dust, debris, and falling pieces of broken brick can all damage your roof material. Make sure to set up a way to contain the mess to avoid paying for repointing and roof repairs. Lay a plastic sheet or moving blanket around the chimney to help catch debris and soften impacts.

Using a drilling (or club) hammer and a pointing (or plugging) chisel, start working along the lines of mortar to cut out the eroded parts. Tap the hammer against the end of the chisel to scrape out the old mortar. Only go about 25 millimeters, around 1 inch, deep to avoid cutting back too much mortar and causing the bricks to destabilize.

Use a dust extractor vacuum to sweep up the dust and debris before you begin applying new mortar. This ensures the mortar has the best grip between bricks.

You may want to remove a few cracked bricks here and there for a totally refreshed chimney look. However, if several bricks are in disrepair, it’s time to have a pro come in to complete the chimney repairs. Removing multiple broken bricks could make the chimney vulnerable to collapsing.

If just one or two bricks need a refresh, you can use a hammer drill, then a hammer and chisel, to carefully break up each brick. Then, remove the remaining pieces of brick by hand and chisel away the excess mortar to prepare for a new brick install. Again, if you aren’t sure how to remove the brick or have trouble, call in a pro at this point.

You need to wet the bricks and remaining mortar on the chimney. Otherwise, these materials can absorb the water from the freshly mixed mortar and cause it to dry too quickly, leaving it cracked and vulnerable to more erosion. Use a spray bottle to apply water on the bricks and mortar.

Now, it’s time to mix up the new mortar that you’ll apply all over the chimney. Use a lime-based mix for homes built before 1920. For modern homes, opt for a Type N premixed mortar or a mortar with three parts sand to one part cement.

Follow the mixing instructions on the mortar’s label. You can hand-mix it using a trowel or mix the mortar with a power drill and a paddle attachment.

If you removed broken bricks, now you can move on with replacing them. Apply mortar in the brick opening, making sure to apply it on the base and sides of the opening but not the top. Then, use a trowel to apply mortar across the base of the brick and slide it into the opening with the mortared side down. Use a trowel to straighten the brick.

Removing and replacing broken bricks can be a tricky part of repointing, so be sure to hire a pro if you’re having trouble with this step.

Finally, it’s time to apply the freshly mixed mortar to the chimney. You can apply mortar to a masonry hawk to hold mortar while you work. Then, starting from the top of the chimney, use a trowel to apply mortar to the joints. Work from the top, moving right to left or left to right before moving downward.

Use a tuck pointer, a great tool for getting clean lines when repointing or tuckpointing a chimney, to smooth out the lines of mortar. Be sure to scrape any excess mortar off the brick surfaces before it dries.