Most repairs to brick and block walls require only basic skills. Catching the damage and repairing it before it spreads wins half the battle for you.
Routinely check a brick or block wall's mortar joints. Soft, crumbling mortar joints let water in to cause serious damage to the wall. Faulty mortar joints call for tuck-pointing -- removing the mortar and replacing it. If the brick has lost its glaze, it's vulnerable to water migrating into its body. Seal the brick with a clear sealer. Chipped brick is also a tip-off that water has intruded and frozen. Treat a chipped brick as you would a damaged brick -- replace it. If you have ivy growing up the wall, its tendrils won't damage mortar that's in good repair, but the foliage can hide potential problems. Check the wall in the spring before leaves appear. To avoid collapsing a section of wall, replace only a few bricks at a time.
About 2 hours to replace a brick or a block.
Small sledgehammer, masonry chisel, drill with masonry bit, pointing trowel, pointing tool, garden hose, scrub brush, plugging chisel, cold chisels, brick set, mortar box, mason's trowel, burlap, 4-inch grinder, old paintbrush, straightedge, circular saw and masonry blade
Chiseling, mixing mortar, pointing mortar
Muriatic acid, mortar, brick, stone, concrete block, wooden wedges
Replace the mortar in the joint by sliding it off the face of a flat trowel and into the recess. Use a narrow trowel or a thin piece of scrap wood to put mortar into the joint and not on the brick. Press the mortar into the joint until it's solidly filled -- mortar will start oozing at the edge of the tool when the joint is full.
To remove a damaged brick, drill several 1/4-inch holes in its center. Next chip out the old mortar with a plugging chisel and small sledge. Using a brick set, break the brick into pieces and remove them. Brush away debris, blow out the dust, and dampen all surfaces of the cavity.
Butter the top and ends of the replacement brick with mortar and set the brick on a pointing trowel. Slide the new brick off the trowel and into the recess, holding the trowel on the mortar in the cavity to keep it as undisturbed as possible. Pry the brick as necessary to make the joints evenly thick. Set a straightedge on the brick and push it level with the wall.
When the mortar has stiffened slightly, scrape away any excess with a masonry trowel and brush the area with a stiff brush. Let the mortar set up until it's fairly stiff and you can just dent it with pressure from your thumb. Then tool the joints with a striker that matches the profile of the original joints. When the mortar dries to a crumbly surface, brush it again.
Use a masonry drill to drill holes into the cores of the block. Then chip out the mortar around the block with a plugging chisel and small sledge, being careful not to damage the surrounding blocks. Set a cold chisel in the holes and break out the front face of the cores.
Using a circular saw with a masonry blade, cut through the side webs at the thickness of the face and score the top and bottom of the center web. Then cut away the face from the center web with a cold chisel. Apply an inch of mortar to the perimeter of the new block face, as well as to the center and edges of the rear surface. Set the new face in place, slipping it in with a pointed trowel.