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Mortar Math: Calculating how much mortar will you need for your masonry project?

The amount of mortar needed for pointing or laying in masonry relies on 4 factors.

 

  1. Project type
  2. Brick, block, or stone size.
  3. Joint size
  4. Neatness

 

For ease  of information I will offer quantities needed per 80lb bag of premix mortar. Not using premix? The weight ratio of your custom mix will be in line with the following information. Bad at Math? I can't help there, shoulda paid attention in school...

Below is a basic chart offering guide lines for amount of mortar needed for various projects. For those of you who like things a bit more verbose, read on! (Brick refers to standard brick at 8 x 2-1/4 x 3-5/8" and Block refers to standard block at 8 x 8 x 16" (Both laid on a common staggered bond)

 Project Type 80lbs premixed Mortar per
Pointing Brick (3/8-5/8") joints @ approx. 3/4" deep 35-40 sq. ft.
Pointing Brick (5/8-7/8") joints @ approx. 3/4" deep
20-25 sq. ft.
Pointing Block (3/8-5/8") joints @ approx. 3/4" deep
200-250 sq. ft.
Pointing Block (5/8-7/8") joints @ approx. 3/4" deep
100-150 sq. ft.
Laying Brick 3/8 - 1/2" joints
35 brick
Laying Brick 5/8 - 3/4" joints
25 brick
Laying Block 3/8 - 1/2" joints
13 block
Laying Block 5/8 - 3/4" joints 8 block

 

Considerations for calculating mortar needed For tuckpointing: 

    • An 80lb bag of premix mortar will yield approximately 0.7 Cubic feet of wet mortar.
    • The most common mortar joint sizes are between 3/8" and 3/4"
    • The most common brick sizes (Length x Depth x Height) are
      • Standard  (8" x 3-5/8" x 2-1/4")     or
      • Modular    (7-5/8" x 3-5/8" x 2-1/4")
      • (Either brick takes up about 18 sq. inches or 8 brick to sq ft without mortar)
    • There are about 6.8-7 brick per square ft with 3/8-5/8" mortar joints, leaving around 20+ sq. inches of mortar for surface area.
    • If the mortar joints are taken out to about 3/4" depth, that puts us at about 0.01 cubic feet of mortar needed to tuckpoint 1 square ft. of brick wall
    • The math would lead you to believe that an 80 lb  bag of mortar will allow you yo tuckpoint 70+ sq. feet of a brick wall.

In a perfect world, on a perfect job, yeah, 70 sq. ft per bag. But Let me save you some agony by saying, this just isn't so. Waste and inconsistency has to be factored. Waste comes in many forms but mostly results from mortar that drops to the ground while pointing and mortar that cures too quickly and needs tossed. 

If you're unsure or still have questions don't hesitate to comment below!


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