MODERN HOME FROM MUD

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A 4 in. slab of concrete is then poured over the building paper. Use a 3:2 1/4:1 mix. Maximum size of the coarse aggregate should be one inch. Do not use more than six gallons of water per sack of cement including the moisture contained in the sand and gravel. Cure the concrete by sprinkling at intervals with a fine spray of water.

At A, Fig. 3, is shown a type of footing suitable for a garage. The brick begins well above the floor level and thus above reach of water when hosing down the floor. To protect the outside wall, the first four courses are plastered with stucco, with the top notched into the wall, B. Foundations for wood floors over basements are shown at C and D. In all cases the bricks are trued up on the inside as in E if the interior is not to be plastered. Otherwise, true up the outside.

At outside doorways lay a beveled 2 X 4 in the concrete to which the saddle or threshold can be screwed, Fig. 4. This illustration also shows the notched brick to receive the door jamb batten, which will be described later.

MAKING THE BRICK. Molds for making the adobe brick are shown in Fig. 5. A 4 in. thickness is commonly used because it cures better than a thicker one. The standard size is 12 X 18 in. having a volume of 1/2 cu. ft. and a face area of 1/2 sq. ft., although in the house shown in the photos, bricks of 16 in. length were used. For the key bricks, adjoining door, and window openings, wooden blocks are nailed inside the molds, as shown, and for rounded corners, curved pieces are installed. A mold, making several smaller bricks for fillers, will come in handy and nave splitting the standard size brick.

Soil must contain sufficient clay to bind strongly when dried after mixing with water. Heavy soils are usually too rich in clay and require blending with sand to overcome excessive cracking during drying. To obtain the general suitability of any soil, mold a 2 in. mud ball from a sample taken below the grass roots. If the ball dries hard and is not easily crushed, it may prove suitable for stabilized bricks. The strength is due to the natural bond of the clay and not to the stabilizer. If the soil is difficult to mix with water and the ball cracks on drying, additional sand or straw is required. Soils which contain alkalies should not be used.

The important ingredient of adobe bricks is a liquid stabilizer which not only renders them waterproof but increases their hardness until they are practically as durable as concrete. Stabilizer is sold under the trade name of Bitudobe manufactured by the American Bitumuls Company, San Francisco, California, and Bitumuls sold by the Standard Oil Co. of California.

Two series of tests should be made to determine the suitability of the soil and the amount of stabilizer required. The first series uses water and soil, for the second series add the stabilizer. If the soil is heavy clay or adobe, mix straight soil for the first brick; for No. 2, use three parts soil and one of sand; for No. 3, two and one-half parts soil, one and one-half parts sand; No. 4, two parts soil and two parts sand; No. 5, one and onehalf parts soil, two and one-half parts sand; No. 6, one part soil, three parts of sand. Mold a jell size brick in each case. Too much clay produces cracking; too much sand decreases strength and resistance to erosion. Place the mold on level ground and force the mud into the corners with the hands. Remove excess mud with a straightedge across the top and lift off the form immediately. In about two days turn on edge. After drying in the sun two weeks or more, examine for cracking and strength, This test determines whether additional blending is advisable. Small center cracks are not harmful.

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