How can formwork impact the final appearance of rammed earth?

Choosing the Right Formwork

For rammed earth construction, formwork is typically made from wood, steel, or a combination of both. The type and design of the formwork can greatly influence the final appearance of the wall. For example, using wooden forms with a smooth surface can produce a uniform, smooth texture, while using steel forms with a grid pattern can create a more rustic, textured appearance. A common formwork design for rammed earth walls involves using 2x4 lumber, spaced 12 inches on center, and covered with a smooth wood or plastic surface.

Formwork Patterns and Designs

The design of the formwork can also create various patterns and designs in the final wall, such as herringbone or grid patterns. To achieve these patterns, the formwork can be modified to include additional supports or dividers. For instance, to create a herringbone pattern, the formwork can be designed with alternating strips of wood, spaced 4 inches apart, to create a diagonal pattern in the finished wall. This technique can add visual interest and create a unique appearance for the rammed earth wall.

Thermal Mass and Durability

In addition to the aesthetic appeal, the formwork design can also impact the thermal mass and durability of the rammed earth wall. For example, using a formwork design with a high surface area, such as a grid pattern, can increase the thermal mass of the wall by allowing for more soil mix to be in contact with the interior surface of the formwork. This can help to regulate indoor temperatures and improve the overall performance of the rammed earth wall.