Monday, December 19, 2016


Concrete block has always been the neglected stepchild of architecture. Even today, the humble material most us call “cinder block” still conjures up dreary images of warehouses, barracks and roadside motels.
Frank Lloyd Wright's Ennis House in Los Angeles
used his vaguely Mayan-looking "textile block" system.
(Courtesy Catherine M.  Austin, ASID)

A few architects have made noble attempts to change block’s image. In the 1920s, for example, Frank Lloyd Wright introduced a system he called “textile block”, in which custom-made blocks cast with various geometric designs were combined into a sort of tapestry in concrete, vaguely Mayan in appearance. A number of his better-known homes used the system, including the affordable-housing prototype “Usonian House”. Yet even Wright’s creative efforts failed to ignite the public’s interest in block.

Some years later, a lesser-known architect of the Prairie School, Alden Dow, devised a truly ingenious twist on the ubiquitous rectangular block: He designed it in the form of a parallelogram with equal sides—not just to be different, but so that he could build walls with perfect 45° angles as well as right angles. Dow built many intriguing homes using this method, but alas, the system passed away with him.

Back to the Sixties: An interesting use of screen block.
All right then, let’s face it: Outside of the Everglades, you won’t find many big fans of concrete block houses. Still, for do-yourself applications such as low garden walls, privacy screens, or foundations for outbuildings, block is unbeatable. It’s much less stressful to work with than poured concrete, since you can stop anytime you like—try that when you’ve got a dump trailer full of concrete starting to harden on you. And it’s actually lots of fun mixing and matching the umpteen patterns and colors of block that are available. Like Wright, you can weave a custom pattern of your own making. Here are a few concrete-block specifics:  

A split-face block, which is made by
extruding a single square block and literally
splitting it in half to produce a broken face.
•  Concrete block is technically referred to as CMU, for "concrete masonry unit". It isn’t cast, but is actually extruded through a die using a very dry concrete mix. The result is a masonry unit that’s relatively light, extremely strong and—let’s not forget—pretty darn cheap.

 Bond beam blocks used to strengthen a foundation.
• A standard concrete block is nominally 8” high by 8” wide by 16” long, so that when it’s laid up in a wall, the joints fall on the familiar 8” module.  However, 4” and 6” widths are also available, along with goodies such as end blocks, wall caps, and bond beams (special trough-shaped blocks that form a horizontal beam when filled with concrete, often used to strengthen walls or span openings).

Creativity makes a difference: This interesting combination
of block textures, colors, and sizes goes a long way
toward overcoming the usual concrete-block doldrums.
•  There are literally scores of different block types and colors available, so you needn’t load up on the usual dull gray variety. In addition to the familiar flat-faced block—available in a surprising range of colors—there are dozens of special types as well: Patterned block embossed with diamonds, triangles, or starbursts; screen block, which has variously shaped openings that form a pattern when laid up; and split-faced block, which imitates rustic quarried stone. Also available is slump block, a cousin of concrete block, whose bulges and irregularity are meant to imitate adobe.

•  Lastly, one caveat: Laying concrete block is a skill that’s not as easy as it looks, but can usually be picked up with a little perseverance. Before you go out and build that cinder-block Taj Mahal in your back yard, however, don’t forget that block walls must be reinforced with steel and then filled with a special thin mixture of concrete called grout. Leave out the rebar and grout, and you’re liable to end up with a lightweight pile of rubble.

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