How many blocks will it take?

Sometimes you can save a lot on a big job by handling some of the work yourself. Building a concrete block wall for a new addition is heavy work, but if you can handle that, it’s not that complicated. Here are some guidelines.

Figure out how many blocks you need.

1) Measure the length of the footing in feet. Multiply that by 3/4 to get the number of blocks per row.

2) Take your finished wall height in inches, and divide it by 8 to get the number of courses.

3) Multiply the two answers to get the number of blocks.

4) Blocks come in different styles. Corner blocks have smooth ends, rather than the ordinary indentation. Multiply the number of corners by the number of courses to get the number of corner blocks.

5) Subtract the corner blocks from the block total to get the number of plain (stretcher) blocks.

6) If the wall height doesn’t work out to an even number of courses, you can fiddle with the thickness of the mortar joint or use a course of ashlars, which are half-height blocks.

Here’s an example. Let’s say we have a 20′ X 16′ addition and we want a 6′-high wall of 10″ block (the 10″ refers to the block’s length.)

1) 20 + 20 + 16 = 56 X .75 = 42 blocks/course.

2) 6′ X 12″ = 72″. 72/8 = 9 courses.

3) 42 x 9 = 378.

4) Two outside corners X 9 courses = 18 corner blocks.

5) 378 – 18 = 360 stretcher blocks.

Next time, we’ll have some tips on mixing mortar.