My idea behind the design of the building was to make it inexpensive, but simple to construct by the locals. This design focuses on simplicity, low cost, and expansion potential of both size and units.
The foundation of the building is built with approximately 72 CEB (compressed earth blocks). These blocks will be in two layers and will raise the foundation approximately 7 inches (18 centimeters). In areas where heavy rain is likely to occur, more blocks can be added to raise the foundation's height. Each CEB contain 2 holes in them so that the corner posts can be inserted or, if needed, rebar for strength.
The corner posts are designed to be placed in any corner with easy attachment of walls. The builder places the post into the corner hole of the foundation and adds aluminum panels or plywood, recycled from older slum buildings. Depending on the climate, the plywood can be sandwiched with EPS to add insulation. These boards are then bolted to the posts and the door is cut out of one of the sides and hinges added.
The floor is composed of plywood boards placed on top of the CEB foundation.
The roof angle is created by adding two extension posts to the rear corner posts (opposite side of door). The roof is then attached with attachment pieces that slide into the top of the posts. The roof is made of the same material as the walls (sandwiched EPS) but with an insulated and water tight hatch on top to release heat buildup inside the room. The design of the building creates an opportunity for a second unit to be added behind the first and to allow rain water to flow away from the center of the two units.
Expansion is simple and can either create a larger room or a community of connected rooms. Each post is designed to attach walls in 4 directions. This allows the builder to also design their own room. With each added room, the material cost is reduced because of the shared walls and posts.
Based on current U.S. prices, the total cost is approximately $207.00 per unit. This cost is based on $60.00 for the steel and $147.00 for 3/4" exterior plywood. I cannot determine price of the CEB, however the hand press used for production of the blocks is $1729.00; one hand operated press can make approximately 800 blocks per day.
The above cost estimates do not include the use of EPS, which will increase the cost per unit.
With materials bought in bulk, i.e. 100 units, the price will be greatly reduced. By building multiple units, interior shared walls can be made with lower grade plywood to reduce cost.