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Repointing a brick wall
Mortar joints deteriorate wherever water can soak them - under windows and walls, around chimneys, behind downspouts, at ground level and at any exposed wall top.
Repairing eroding and cracked mortar joints is called pointing, repointing or tuck-pointing.
Hardware stores and builder's merchants carry the tools and materials needed for pointing brick.
You will need:
Hammer, flat utility chisel, safety glasses, dust mask and whisk broom, trowel, pointing trowel and waterproof gloves.
Here's how:
1. Break out old mortar using a hammer and cold chisel or a flat utility chisel that’s narrow enough to fit into the joints. Remove old mortar until you reach a solid base for bonding the new mortar. If the mortar is so soft that the bricks are loosening up, you’ll have to remove and properly reset them. If the cracked mortar is harder, make a relief cut down the centre of the mortar joint using the pointed edge of the chisel and then gently chip out the mortar that contacts the brick.
Position a flat utility chisel at the edge of the brick and drive it toward the relief cut to fracture and remove the mortar.
Once the old mortar is removed, dust out the joints. Prepare the joints to receive new mortar by misting them lightly with a garden hose sprayer.
2. Mix mortar until it’s the consistency of peanut butter and clings to an overturned trowel. It should be stiff but not crumbly.
Allow the mortar to “rest” for 10 minutes as it absorbs the water, then remix it using your brick trowel. Don’t try to revive mortar that’s drying out by adding more water to it. Mix a fresh batch instead.
3.
Pack mortar tightly with no voids for the strongest, most water-resistant joints.
Fill deeper joints (those greater than 20mm) in two stages. Allow the first layer to partially harden (until a thumbprint barely leaves an indentation) before adding the second layer.
DIY Tip:
In hot weather, work in shaded areas first (if possible) so the sun won’t dry the mortar too fast.
4. Use a pointing tool match the contour and depth of existing mortar joints. Repoint brick sills and other horizontal brick surfaces with flush joints to promote drainage - regardless of the type of mortar joint in your vertical walls. Allow the mortar to cure to “thumbprint” hardness before you finish the joint. Shape the vertical joints before working the long horizontal joints.
5. Use a soft-bristle brush to remove mortar chunks on the brick face before they harden. The brush keeps the mortar from smearing. If you do smear mortar onto the brick, you’ll have to go back later and use a chemical cleaner.
6. Mist the new mortar twice a day for two days using a hand pump sprayer or a light mist from a garden hose to help it harden.
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