How to Repair Masonry Work

Repairing masonry work need not be something that puts the fear of a Mayan god into you. Get yourself a trowel, a mallet, a chisel and determination and, well, I guess you should get a rag with which to wipe away the sweat. Once you’ve got all those things, repairing masonry is a gas.

Let’s say you want to fill in a big crack in cement blocks. The first thing to do is to use a large wire brush that lets you comb away the debris. You may be tempted to chisel out the crack, but this would be a mistake because the mortar that will need to be applied will stick to a clean crack whereas the chisel is just going to damage the face shell of the block. Pack the cracks with a flexible backer rod and then moisten the length of the crack itself and brush the surface with a bonding grout made of equal parts cement and sad. Mix this with water so that you get a consistency roughly equal to that of thick paint. Fill the crack with the mortar and press it into the crack using a sharply pointed trowel. Or, you know, well, you could just use a commercial patching paste, but where’s the fun in that?

Every once in a while a concrete block actually breaks down and needs to be replace. This is the case when that mallet and chisel come in handy. Chisel away the weaker sections of the concrete block shell. Moisten the area and apply mortar. Here come the tricky part. You have to cut a face shell from the new block. Apply mortar and press the block into its rightful location.

Replacing a broken brick wall is similarly done. You use your chisel to carefully cut away the damaged brick and its surrounding mortar. Clean out the hole left in the wall and moisten it before spreading mortar on the bottom of the surface. Dampen your new brick and mortar the top and the sides. Carefully slide into place using your trowel or hawk. (If you have to ask what in the world a hawk is in the world of masonry, you really should not even be attempting this.) Add some more mortar as needed when placing the new brick into the slot.

Stucco masonry repair differs from working with bricks or concrete blocks. You still need that chisel so that you can loosen up the stucco and clear it away. Use a strong brush to clean away the area of remaining stucco pieces. Moisten the area and then use a trowel to make the area as level with the surrounding surface as possible. Use your darby (see note about hawk) smooth on new stucco. Add as much stucco as you need. You’ll need to keep the stucco moisten for about five days until it has cured. (See note about hawk.) Mix the finish coat of stucco and apply with a float or a large paintbrush if you don’t have a float. Texture can be created by artistic application of freehand strokes or just spattering with the paintbrush.