Date: Sun, 22 Nov 1998 20:45:09 EST

I have to do a report on the bricklayers formula N = 7LH. Can you give me any information on this.

Thanks, Rachel
Middel student

Hi Rachel,
I have never seen this formula before so I tried to discover what it means. I found a brick and made a rough measurement of its face and got a length of 8 inches and a height of 2.5 inches. Assuming that L and H in your formula stand for length and height, for one brick I calculated 7LH = 7x8x2.5 = 140 square inches. This is almost 144 square inches which is one square foot. Thus if a wall measures L feet by H feet then 7LH will give you approximately the number of bricks in the wall.
   I made a very rough measurement of the brick to get this result and didn't consider the mortar. I suggest that you also measure a brick and the mortar between them to get a more accurate result. Does the estimate 7LH give too many bricks or too few? Which would the bricklayer want, an estimate that gives a few too many bricks or a few to few?


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