How to repoint brickwork
If the mortar's looking crumbly, it's time to take on this simple repair
Most people call the mortar between the brickwork on walls and chimneys “chinking,” but its real name is “pointing,” and if you have noticed this spring that yours is all crumbly and falling out of the joints — usually due to repeated water infiltration and the freeze-thaw cycle — then it’s time to set things right with a simple, if time-consuming, repair. Repointing, or tuck-pointing, is easy enough over relatively small areas, but if an entire chimney needs doing, or if the pointing is in such bad shape that a lot of bricks are actually coming loose, consider hiring a pro.
1. To get things rolling, you’ll need some masonry tools, including a large triangular trowel, a narrow rectangular tuck-pointer that fits the mortar joints (they’re sold in a variety of widths), a “plugging” chisel to remove the old mortar, a shaping tool called a jointer, and a 2-lb “mini-sledge” hammer. To fill the joints, buy a bag of Type “N” mortar mix, not Portland cement which is harder than the bricks themselves and will lead to their destruction. If colour-matching is a concern, building centres also sell pigments that you mix right in with the mortar.
2. Starting at the top of your repair area, use the plugging chisel to remove the old mortar to a depth of about 2.5 cm. Don’t get too hammer-happy; if you encounter joints that seem sound, leave them be. The idea is just to get rid of the crumbly stuff. Clean out any debris with compressed air, a Shop-Vac, or a deftly wielded bristle brush, then wet down the whole works, bricks and joints, so the existing masonry won’t suck all the water out of your new mortar. Working in small batches on a scrap board, use the trowel to mix up some fresh mortar with just enough water that it remains quite stiff (you don’t want soup here). Scoop a gobbet of mortar onto the back of the trowel, flatten the pile a bit with your tuck-pointer, then hold the trowel up to a joint. Slice off a strip of mortar and shove it into the joint, filling the gap to the face of the brick. This will be messy and awkward at first, but keep at it; with practice you might even reach that virtuosic level at which you can simply lift a slice of mortar onto the back of your tuck-pointer and flick it neatly into the joint. Good luck.
3. When all the vertical and horizontal joints are filled — that was a bit of work, wasn’t it? — wait about 20 minutes for the mortar to set up, then go over all the joints with the jointing tool, smoothing them completely or leaving ruffled edges, whatever matches the other joints. The shape of the joints was determined by the mason who did the original work, and they might be convex, concave, square, set flush with the face of the brick, or recessed. Sometimes, the back of a small spoon or some other improvised tool is needed to create a perfect match. You may even need a profiling tool; the more common styles are likely available wherever you bought the tuck-pointer.
4. If you encounter a loose brick, chisel away enough mortar so that it can be removed, then chip away old mortar from the brick and from the inside of the hole whence it came. Wet down the recess, spread a bed of mortar on the bottom of the hole, then butter both ends and the top of the brick as well. Holding the brick on the back of your trowel, level it with the hole then, squoosh, shove it right in, tapping it home with the butt of your trowel handle. Scrape away any excess mortar, flatten the joint with your tuck-pointer, then, after 20 minutes or so, tool the mortar with the jointer as above. (Nota bene: When mortar slops onto bricks where it shouldn’t be, scrape or flick it off with a trowel. Never wipe it off or the resulting smear will become a permanent part of your cottage. You can also wait a few hours until the errant blob hardens, then knock it off with a hammer and chisel.)
5. When your new mortar has fully cured, usually after four or five days, scrub the repair area with a stiff brush to create your final finish. Perfecto! Finito! Well, almost. You will now, of course, set about fixing the corrupted flashing, leaky eavestroughing, or failed downspout that caused your mortar damage in the first place. It’s either that, or repeat this tuck-pointing ballet in a few years’ time. Take your pick.
This article was originally published on June 12, 2007