The Owner-built Adobe House

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The standard size adobe brick used in post adobe construction and in 16-inch-wide (40.6 cm.), double-brick, solid-wall construction is 4 inches by 7-1/2 inches by 16 inches (10 cm. X 19 cm. X 41 cm.). The standard size brick in New Mexico and similar areas where the bricks are covered seems to be 4 inches by 10 inches by 14 inches (10 cm. X 25 cm. X 36 cm.).

Make the brick dimension the inside dimension of your molds. The molds, however, should be made 4-1/4 to 4-1/2 inches (11-12 cm.) high, since the bricks generally slump when removed from the mold. My bricks actually ranged from 3-1/2 to 5 inches (9-13 cm.) in height . . . a variation that produced an interesting pattern in the finished walls.

Make all wooden molds from hardwood, Douglas fir, or southern pine . . . these woods will withstand the wear and tear of brickmaking. The molds should be painted or shellacked inside to provide a slick surface. Rough surfaces make the bricks difficult to remove from the molds.

To build a five-brick mold, cut two pieces 4-1/2 inches wide by 1 inch thick by 45 inches long (12 cm. X 2.5 cm. X 114 cm.). Cut ten pieces 4-1/2 inches by 1 inch by 16 inches (12 cm. X 2.5 cm. X 41 cm.). Put the outer frame together with wood screws. Add two divider strips between each two brick openings and make the bottom opening (for each brick) 1/4 inch (0.6 cm.) wider than the top. This allows the brick to slip out easily. Add regular drawer handles at either end of your mold or make them out of scraps of wood. Also protect the four edges of your mold with sheet-metal reinforcing (Fig. 3).

Some adobe builders also make eight- to sixteen-brick molds out of 2 X 4's. Any mold, however, that makes more than eight bricks at a time requires two persons to lift it off.

A clever innovation for making adobes is an 8 foot by 8 foot (2.4 m. X 2.4 m.) outer shell made of 2 X 4's. Pour the mud into the form and level it with a 2 X 4. After the mud sets for about two hours, remove the outside 2 X 4's. Cut the adobes to size with a piano wire stretched across a 2 X 4 bow. This method is much faster than most others.

In addition to molds, you can buy machine presses for casting bricks by hand. The CINVA Ram is a light, portable adobe press developed by the Inter American Housing and Planning Center (CINVA) Bogotá, Colombia. A similar style of press is the Ellson Blockmaster . . . manufactured by Ellson Equipment Ltd.

The bricks made from these presses are more uniform in size than hand-poured bricks. Since they are made under pressure, they are also almost twice as strong as cast bricks. Generally, however, making bricks with a press is slower than casting with a form.

STARTING PRODUCTION

As soon as you have pretested your soil for clay content, established the amount of emulsified asphalt needed, and constructed your molds, you are ready to start producing bricks.

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