How to Mortar a Concrete Block

Concrete blocks are weather resistant.

Concrete blocks have the benefit of being fire and weather resistant and come in many interesting shapes and textures. Because they are heavy, a structure built with concrete blocks will usually require a base of poured concrete to support the weight of the blocks.

Things You'll Need

• Concrete blocks
• Mortar
• Level tool
• Rubber mallet

Instructions

1. 

   Spread mortar 1 inch thick using trowel.

   Use your trowel to spread mortar on one corner of the concrete base 1 inch thick and as wide as your first block. Spread the mortar the length of three blocks. Make a furrow (narrow groove) with your trowel down the center of the mortar to help bond the concrete blocks.

2. 

   Align the corner block.

   Place the corner block in position and use the level to check alignment. Use the trowel to apply mortar to the end of next block making a 3/8-inch mortar joint. Press the next block in position beside the corner block.

3. 

   Continue the pattern to install all blocks.

   Use your level tool every five or six blocks to check the tops and sides of the blocks for alignment. Every three rows measure length, height and corners. Use the rubber mallet if necessary to tap blocks into place if they are uneven. Continue the pattern of laying concrete blocks until job is complete.

Tips & Warnings

• Concrete blocks should be laid on a prepared base of poured concrete that will hold the weight of the blocks.

• Build up the corners of each row first, and tie string between the corners as a guide.

• Only mix the amount of mortar needed for one and a half to two hours.

References

• Millard Lumber, Inc.: Laying Concrete Blocks
• Realtor.com: Mixing and Handling Mortar

Resources

• Ask the Builder: Poured Concrete Walls vs. Concrete Block