How to Join a Brick Wall to a Block Wall

Dig out a foundation from the edge of the block wall with a flat-tipped shovel. Make it about 10 inches wide and 5 inches deeper than the bricks. Set a bubble level on top of the trench and dig out any high spots until the foundation is level.

Spread 4 inches of angular gravel over the foundation with a hoe, and compact the gravel by hitting it with the flat side of a tamping tool.

Stack the bricks within easy reach of the foundation so you can set them quickly before the mortar begins hardening.

Use a tape measure and utility knife to cut a length of foam backer rod to fit vertically from the bottom to the top of the block wall.

Stir a sack of ready-mix mortar in a wheelbarrow with a small amount of water, and blend it with the end of the hoe. Scoop small piles of mortar over the gravel, and spread it 1 inch thick with a notched trowel.

Hold the bottom of the foam backer rod vertically against the middle of the adjoining end of the block wall, and have someone hold the rod straight up. Spread 1/4 inch of mortar over the ends of two bricks, and set them side-by-side in the mortar against the foam backer rod. Spread mortar over the ends of the next set of bricks, and place them parallel to each other and against the ends of the first set. Continue laying the first course two bricks at a time, and hit them lightly with a hammer to make them level.

Start the second course with two half bricks to offset the joints. Spread 1/4 inch of mortar over the first course and ends of the bricks you are setting. Place the half bricks tight against the expansion joint, and continue to set the second course by laying two bricks at a time until it is complete.

Back-fill the remaining gap in the foundation with angular gravel and compact it.

Build up the brick wall one course at a time until it is level with the block wall.

Load a tube of expansion joint sealant in your caulk gun, and fill in the space between the face of the wall and the foam backer rod. Begin at the front of the wall, and apply the sealant in thin layers from the bottom up so it doesn’t drip. While the first layer sets, caulk the back of the expansion joint from the other side of the wall. Repeat this process until the spaces behind and in front of the expansion joint are filled with caulk, and remove excess from the surface with a putty knife.