Rammed Earth Homebuilding

Article Tools

Image Gallery

Print

E-mail

Comments

RSS

Once erected, the formwork presents a big open box into which workers can compact as much as 8 1/2 cubic yards of prepared soil without stopping. Corners are more difficult to form than straight sections of wall. The forces from ramming are compounded at the far out side corner of the formwork, and it demands extra precaution to keep a corner straight and the formwork tight. In fact, corners present such significant headaches that frequently rammed earth buildings are designed without earth corners altogether. That is, either door openings or full-height windows are positioned to butt against straight wall sections at the building's corners or else side walls extend beyond the ends of the building and the cross walls butt. (Viewed in a plan, this configuration is in the shape of a T.)

Building the Walls

Constructing a complete wall system using the basic formwork is simply a matter of building one panel after another around the perimeter of the building, discontinued at door openings and partial height at window locations. The first step, regardless of which method is used (freestanding or panel-to-panel), is to construct the corners. This way, the correct alignment of the walls can be maintained. String lines can be used to check alignment as each new form is set. If concrete columns are specified in the design, each panel is spaced six inches from its neighbor. Where doors are to be installed, a panel is omitted, and where windows are to be installed, a partialheight panel is built. The simplest system calls for the door and window openings to extend to the height of the bond beam, thus eliminating the need for separate lintels. (More on doors and windows later.) In the panel-to-panel system, where no concrete columns are used, wall sections are rammed directly against one another, end to end.

When building this system, we first mark out on the foundation the exact position of each of the wall sections. Door and window rough openings are calculated and marked out directly on the foundation. The mark actually specifies the positioning of the endboard for each setup. With all the sections laid out, first build the corners to provide a point of alignment for the walls, then form and construct every other panel around the perimeter, leaving a full-panel gap between each section.

The reason for the gap is that freshly constructed sections of wall are fragile, and when forms are clamped onto green walls there is a risk of cracking and other damage. By first making a complete circuit around the perimeter, building every other section, the walls will have enough time to cure, so that, when the intermediate panels are built, the seam between the two will be clean and straight.

The Essential Soil

Soil is classified by the size of its individual particles, not by its parent rock. Generally speaking, there are five basic soil types: gravel, sand, silt, clay, and organic. The five soil types are rarely found separately in nature.

RSS | Comments | E-mail | Print