Estimating Concrete Blocks for Dummy Masons

Laying concrete block

Lots of statements can be taken more than one way, depending on attitudes and context among other clues. Heck, that's the whole reason emoticons were invented... Questions, however, are generally more clear-cut; assuming you have the background necessary to answer the question. That's not always the case among Leaf Group (formerly Demand Media Studios or DMS¹) freelancers: without proper knowledge the dumber asses among them produced some pretty stupid output... like the Hunker.com article "How to Calculate the Number of Concrete Blocks in a Wall," which contributor Tom Kantain tackled.

We suspect that anyone with the tiniest bit of background in masonry would recognize that question for what it obviously is: estimation of the materials necessary to build a wall of concrete block; say, a foundation, a block-wall garage, a retaining wall, or something else. That, however, is not what a guy with a MA in Philosophy (and a "Bachelor of Laws") immediately thinks, No, Kantain addressed his topic... philosophically:

"It's natural for a certain kind of mind to wonder how many bricks or blocks are in a wall. The simplest and surest way to obtain that number, of course, is to count them all..."

Actually, the simplest way would be to count the number of blocks per row, count the number of rows, and multiply... but never mind... Tom eventually gets to the concept of estimation, of course, but he has a few problems. For instance, as eHowians are wont, Kantain would have you measure a single block and calculate its surface area, then divide the total surface area by the surface area of one block. Heck, his resource even prompted him to remember to allow for mortar – a first for eHow, we think. That's where he ends up with the rather bizarre statement, "...if your standard concrete block is 1 foot by 0.5 feet and is separated from its neighbours by a half-inch of mortar, then each block accounts for 1.0417 x 0.5417, or 0.5643 square feet..."

...which, unfortunately, is not the dimensions of a "standard concrete block" -- they're more likely to be [nominally] 8"x8"x8" or 8"x8"x16" -- and the typical mortar joint is 3/8", not a half inch. Too bad Tom didn't do his research, though maybe dimensions are different in the UK...

After all that explanation and wrangling of numbers, Kantain didn't mention some of the most important steps in estimation. First, you subtract the area of any windows and doors in the wall, and second, estimators always add 5 to 10% for breakage and mistakes. Our Dumbass of the Day clearly didn't know enough about the question to remember those non inconsequential points -- hence the award. Of course he could have sent them to an online estimator -- but then he wouldn't have collected his fifteen bucks...

¹ Around the Antisocial Network, we had a saying: "You can't spell 'dumbass' without 'DMS'!" Too bad the company's changed its name...

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