How to Build a Small Block Wall Along a Slanted Sidewalk

Mark off the area for the block wall with spray paint or rope. Dig out the footings for the small wall with a shovel, making the width twice as wide as the width of the blocks. Dig down at least one-third of the height of the wall. For instance, a 3-foot wall needs a 1-foot-deep footer.

Level the bottom and sides of the trench with a level so that the finished wall will stand straight. Remove the dirt from the area. Place a board along the bottom of the trench and rest the level on it to check for level. One side of the ditch will be deeper than the other if the ground slants.

Line the side of the trench with wood planks held in place with wood stakes. Place the stakes every 3 to 4 feet on the inside or outside of the planks to keep them straight then pound them in place with a hammer. Drop the stakes lower than the top of the planks.

Drop a drainage pipe onto the topside of the trench outside of the wood plank lining if the ground slopes toward the sidewalk. Position the pipe to angle at least 1 inch for every 20 feet. Cover the pipe with several inches of gravel.

Mix a batch of concrete in a concrete mixer, adding only enough water to make a thick, pudding-like mix. Alternatively, you might consider hiring a cement truck to deliver the concrete for the footing if the wall is long.

Pour concrete into the footing framework, using a 2-by-4 to level the surface with the top of the forms. Let the concrete cure for at least a week before removing the wood forms.

Place the first row of blocks on top of the concrete footer without any mortar to see how they fit and which blocks might need to be cut. Remove the blocks and cut any necessary with a masonry chisel and hammer.

Smear a 1-inch-thick layer of mortar over the footing as wide as the blocks with a trowel. Drag the trowel through the middle of the mortar to form a ridge. Set the first block in place and push on it gently. Scrape off any extra mortar and use the level to ensure the block is plumb and even.

Butter the sides of the next block with 1/2-inch of mortar and place it on top of a layer of mortar next to the first block. Press the block in place, remove the extra mortar and check if it sits level. Continue until you finish laying the blocks for the first course.

Start the second course by centering a block over a seam in the first row. Build the second and consecutive rows the same as the first, alternating seams and cutting blocks to fit the ends. Check often to make sure the blocks are level in every direction, tapping them slightly with a mallet if necessary.

Clean up the joints of the block wall by dragging a jointer along the surface of the damp mortar. This will create a slight indent.

Fill in the soil at the base of the wall to cover the footing. Rake it to level and even out the soil to the edge of the sidewalk.