Laying Brick over Concrete

Lead Image for Laying Brick over Concrete
  • 8-40 hours
  • Intermediate
  • 100-750

If you have a concrete foundation already in place, laying brick over it becomes a much easier, quicker process. Building a brick wall, outdoor oven or barbecue with mortar requires a stable foundation. It is not something that can simply be done over loose ground. A concrete foundation must be laid before a wall or some other structure can be built. If you skip this step, the masonry work is put in jeopardy of collapsing or sinking into the ground. In this article, you will learn about the basic method of laying brick over concrete including the initial layout and the actual mortaring and curing of the joints.

Laying Out Brickwork

With the concrete foundation in place, you have a flat, stable area on which to build your brick structure. The first thing to do once you have the bricks and all the other materials is to experiment with different patterns. Start by setting bricks in various arrangements to see which one suits your fancy. If you are building a 4-side garden box, decide how high and how thick you want it to be. Once you have decided, you need to mark the foundation to give yourself a guide. Snap chalk lines on the foundation on all 4 sides. These will represent the front edge of the wall. Mark the exact space between each brick with pieces of 3/8-inch dowel. With the bricks laid out, mark on the foundation with a pencil the placement of each brick. You can then begin to mortar the joints and on the underside of the row. The corners may present the biggest challenge. You will almost certainly have to cut bricks to make it work.

Laying Out the Second Row

With the first row of single bricks laid, you can finish out the first row by laying out the second column. Use the spacers and mark their position as before. When you are ready for the second row of bricks, lay the bricks crosswise in relation to the underlying row while at the same time staggering them so the middle of one brick is over the joint of the lower one. Continue in this pattern for the entire wall. At the corners, a common bond can be used which consists of 2 ¾-size bricks and 2 ¼-size bricks to join the sides.

Mortaring and Maintaining the Level

Use what is called a masonry story pole with exact markings on it. You hold it vertically up to your wall to ensure that the brick rows are level and the mortar joints are uniform. The mortar you mix for the job should be thick enough to hold its shape when you make a ridge in it with the trowel. When you apply mortar into a joint, scrape away the excess. Never slide a brick to equalize its position unless you just laid it (within the last 2 minutes). If you have to, strike the joint, reset the brick and reapply mortar. Have the story pole and a level always handy and constantly check your progress.

Brick walls over 3 feet high you must have a permit to build, and they must be reinforced below the surface of the ground. For building simple garden or landscape retaining walls, no permit is required nor is any reinforcement. However, make certain you have a clear idea of how the bricks will stack before you start. Laying bricks over concrete is the only way to make a mortared brick wall structurally sound. Once the entire structure is complete, keep the joints moist for 2 or 3 days afterward. It need not be soaked, but a thin layer of water helps the mortar cure properly. When completely cured, go over the entire structure with a stiff brush to clean up the mortar residue.