How Much Mortar Do I Need for Cinder Blocks?

Pattern and Size

• The size of the blocks you are using directly affects the amount of mortar required for your project. Larger blocks require less mortar because there are fewer joints, while the opposite is true of smaller blocks. In addition, while you might opt to use a recommended joint width of 1/2 inch on the finished block, you could also choose to go with a 3/4-inch joint, which will require more mortar.

Structural or Visual

• While structural block projects will require that a minimum of mortar is used between the blocks, a purely visual block project can use more or less mortar, depending on your personal preferences. For example, building a foundation wall may require a minimum of 1/2-inch joints, while a garden wall that is only for decoration can have however much mortar you prefer between the blocks.

Recommendations

• There are two ways to estimate for mortar in the average circumstance. You can opt for the per-square-foot estimate or the per-100-blocks estimate. The average for 100 square feet of 4-inch blocks is 13-1/2 cubic feet of mortar, with 8-1/2 cubic feet required for 8-inch blocks. For 100 blocks of 4-inch material, the recommended mortar estimate is 6 cubic feet, or 7-1/2 cubic feet for 8-inch blocks. These are recommendations only, and you can order more or less.

Extra Material

• In any construction project, you should always order extra. The normal recommendation for extra material is 15 to 20 percent extra material. This allows you to cover any potential mistakes, as well as any unplanned necessities that might arise due to conditions in the field being slightly different from what is on paper with the blueprints.