This is a small shelter example measuring 2.03 x 2.75 meters (6'8" x 8'). It is wide enough for a bed to fit across and could be used as a small bunk house or bedroom. Mold development, though it leads to ideal production techniques, has been temporarily set aside in favor of frame support only because of the time consuming nature of mold construction. Although the finished mold in the previous chapter is for a larger roof and is ready for example construction, frame support is a more commonly understood method presented here to provide a full description of methods available for immediate production.
Rafters are a quick support technique to build a roof of any material. Two by four centimeter wood was used in this test example to explore strength of materials and simulate the approximate size of bamboo or fast growing saplings harvested at a similar size. Bamboo and straight saplings are a common building material where roofs like this are likely to be used.
Bamboo or wood when encased in the composite of fiber, acrylic and cement becomes somewhat secondary as a structural element. As will be seen further on in this section, the shape of the fiber around bamboo or wood becomes a composite material girder similar to what would be produced in the molds.
Although the wood was connected with screws in this model, a rapid bamboo connection method using the same materials employs strips of fabric soaked in the cement and acrylic and wrapped around the bamboo to make the connections. The appearance of wrapped unions is similar to a bandage wrap applied by a doctor to a sprained joint, examples are presented in the chapter on bamboo trusses. These unions are very strong and need not be as thick as a cast for a broken bone. The wrapping technique used to make the ferrocement encased wicker chair pictured above also serves well.
This section begins with the finished roof. Details of structural construction will follow for those who wish to contemplate economics and methods which might apply to available materials in their region. Acrylic is rare and expensive in some areas but it is easily transported in barrels or transport tanks; cost is reduced significantly by using large containers.
Areas plagued with forest depletion combined with rapid rot of wood constructions due to high humidity and moisture will benefit economically and environmentally if they facilitate use of acrylic through public assistance for import, warehousing and tank storage. Bangladesh, for example, is a major burlap producer which fits this description.
A system of production not yet explored is this frame type set on a rotating axel. The ferrocement.com roof laboratory will require an outlet for finished shelters and a larger funding base before testing portable production lines which will yield multiple completed roofs and structural components.
Start with a measured piece of burlap which has been soaked in water for 20 to 30 minutes and then set aside until all excess water has quite dripping from the roll.
Unroll the damp burlap on a plastic covered surface and use a large brush to cover the the exposed side.
Fold back like turning the covers back on a bed to cover the other side, notice the straight fold line separating two visually distinct areas. It is easy to pull the wrinkled area flat before rolling the soaked burlap back onto a pipe for the next step.
Acrylic : 30 Liters = 7.9 gallons
Burlap : 16 Meters2 = 19.1 yards2
Wood US : 2x4 in (2.25 @ 8' long & .75 @ 8.75' long)
Wood cm : 8 @ 2x4x120 & 3 @ 2x4x275 trimmed to fit
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