| Building Green on Your Own, Part 2 |
 |
 |
|
Adobe Adobe consists of bricks fashioned from local subsoils and contains a mixture of clay, sand, and chopped straw or raw horse manure for strength. It is wetted, mixed, and poured into wooden forms and left to bake in the sun. After some drying the forms are removed and blocks are left to dry completely. Forms are reused. For the walls, adobe bricks are laid in a running bond (overlapping pattern), just like modern bricks or stones, directly on a foundation. A mortar made of the same subsoil is used to hold the bricks in place. Earthen plasters are better suited for adobe than cement because they expand and contract at the same rate as the adobe bricks. This decreases cracking and repairs, and allows wall moisture to escape. Adobe provides good thermal mass. Add insulation inside or outside for additional comfort. Rammed Earth This is a mixture of clay and sand compacted into forms. Sometimes cement is added to the mix. Wooden or steel forms are erected on the foundation. A 70 percent/30 percent mixture of moistened sand and clay is shoveled into the forms about half a foot at a time, and then tamped by a pneumatic compressor. When filled, the forms are removed. The block is usually 12 to 18 inches thick and 6 to 8 feet long. A new form is placed next to it. The walls, then the roof, windows, and door frames are built in order. The advantages of rammed-earth construction are fireproof walls with good thermal mass. The disadvantages include the numerous forms and heavy equipment required to make and move the blocks. Rammed-earth tires are a variation of basic rammed-earth construction. These dwellings are typically built into south-facing slopes. Tires are laid out on compacted soil, in a U-shape for one room. Cardboard is placed under the tire to prevent the dirt filling from leaking out. One worker fills the tire while the other tamps it. After the first row is completed, a second row is placed on the previous row in an overlapping (running) pattern, and the process continues until the wall is finished. A roof is attached. The walls are mud-plastered or finished with cement stucco. The disadvantage of these rammed-earth tire "earthships" (as they're sometimes called) is that they can be damp. Protect the walls and foundation from ground moisture. Waterproof the walls, and install a French drain (a ditch filled with gravel and rock that redirects surface- and groundwater away from the structure). |
Discuss this item on the forums. (0 posts)