How to Calculate How Much Grout for Block Wall

Concrete block walls require less mortar than brick walls.

Concrete block walls are used in the construction of buildings and structures of all kinds. Concrete blocks are larger than bricks and small stones, so a wall constructed of concrete blocks has fewer seams than one constructed of other, smaller materials. As a result, you need less mortar or grout to build a wall with concrete blocks than with many other common building materials.

Things You'll Need

• Tape measure
• Calculator

Instructions

1. Measure the size of the wall you intend to build. You need to know the square footage of the wall in question, so measurements of the height and width of the wall are required.

2. Multiply the height of the wall by the width of the wall. The result is the square footage of the wall. Square footage is based on a single layer of concrete blocks. If you intend to use more than one layer of blocks, double the square footage you measure.

3. Calculate the amount of grout or mortar you need based on the size of the concrete blocks you are using. If you are using 4-inch blocks, you need approximately 13 1/2 cubic feet of grout per 100 square feet of wall with a 3/8-inch joint thickness. If you are using 8-inch blocks, you require approximately 8 1/2 cubic feet of grout per 100 square feet with a 3/8-inch joint thickness.

4. Calculate the amount of grout or mortar you need based on the number of blocks you have if you are not able to measure the planned square footage or do not know the projected final size of the wall. For every 100 blocks sized 4 inches, you need about 6 cubic feet of grout for a 3/8-inch joint thickness. For every 100 8-inch-sized blocks, you need about 7 1/2 cubic feet of grout for a 3/8-inch joint thickness.

Tips & Warnings

• The amount of grout or mortar you may require to build a concrete block wall can vary based on the thickness of seams and the amount of filling you perform.

• Four-inch blocks include 4-by-4-by-16-inch, 6-by-4-by-16-inch, and 8-by-4-by-16-inch blocks.

• Eight-inch blocks include 4-by-8-by-16-inch, 6-by-8-by-16-inch, 8-by-8-by-16-inch and 12-by-8-by-16-inch blocks.

• Use caution when working with heavy materials such as cement block. Falling blocks can cause serious injury.

References

• Augusta Concrete Block Company: How to Figure Your Job
• ACE Hardware: Laying Concrete Blocks
• Wickes; Calculating Building Material Quantities; December 2009