Patent Publication Number: US-8984841-B1

Title: Low cost roofing techniques

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to building construction techniques, and particularly to low cost roofing techniques for providing economical roofs for buildings. 
     2. Description of the Related Art 
     In many countries, shortages of quality building materials and skilled labor render construction costs of adequate and safe housing prohibitive. To allay this situation, some countries have promoted policies that encourage low-income individuals and families to self-construct (do-it-yourself). Adoption of such policies, however, is insufficient if the technology is not available to assist the (mostly unskilled) individuals in the construction of safe, building standard-compliant, and relatively low-cost dwellings. This is especially true when attempting to construct a roof for a home or building. Generally, the home or building structure to be erected is limited to two stories in height so that conventional ladders may be utilized when constructing the roof. The building industry would certainly welcome techniques for constructing a roof that would enable unskilled laborers to employ low-cost materials to construct a building standard-compliant and serviceable roof for a home or building. Thus, low cost roofing techniques solving the aforementioned problems is desired. 
     SUMMARY OF THE INVENTION 
     The low cost roofing techniques provide techniques for construction of low-cost roofing. It has been determined that iron or steel reinforcement and cement are the major cost elements for materials in traditional roof construction, amounting to about 59% of the total costs. The labor costs amount to about 12% of the total. Since labor costs for do-it-yourself construction would be negligible, the solution to the problem is to (1) reduce the proportion of iron or steel as low as possible based on the content of the cement, and (2) reduce the proportion of cement by employing substitute (low-cost) materials that may be readily available to mix with the cement. These substitute materials include, but are not limited to, suitable agricultural wastes, such as rice husk ash, crushed used brick rubble, and pozzolana. Mixing these low-costs materials (based on availability) with cement in proper, pre-determined proportions would reduce the amount of cement needed. The technique involves forming a plurality of supports spanning the open space between the walls of the structure and mounting a plurality of dome-shaped sheet metal elements on the supports, forming a series of ceiling vaults. The concave surface of the dome-shaped elements would form the ceiling. The convex or outer surface of the dome shaped elements would form the inner layer of the roof. The cement mixture would be deposited on the convex or outer surfaces of the dome-shaped elements to form a second layer for the roof. 
     Accordingly, the invention presents techniques for constructing a building standard-compliant roof, the techniques being easy to accomplish and readily employed by unskilled laborers. The invention provides improved elements and arrangements thereof for the purposes described which are inexpensive, dependable and fully effective in accomplishing their intended purposes. 
     These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an environmental, perspective view of a roof being installed using low cost roofing techniques according to the present invention. 
         FIG. 2  is a partial, perspective view of a domed ceiling built using low-cost roofing techniques according to the present invention, shown from below. 
         FIG. 3  is a partial front view in section of a roof employing low cost roofing techniques according to the present invention. 
     
    
    
     Similar reference characters denote corresponding features consistently throughout the attached drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to  FIGS. 1-3 , the low cost roofing techniques involve supporting a plurality of arched or dome-shaped sheet metal elements  12  across an open space defined by the walls  14  of the building, generally indicated at  10 , that is being constructed. At least one side of each element  12  is supported on a support member  16 , the support members  16  extending in parallel between opposing walls  14 . The concave face  12   a  of element  12  forms the ceiling of the structure. The convex face  12   b  of element  12  functions as an inner layer for the roof. The support members  16  comprise a 1:1 mixture of poured red brick and lime pozzolana ash. Wooden forms are used to contain the mixture until it hardens. A layer of the concrete mixture  18 , as described above (i.e., rice husk ash, crushed used brick rubble, and pozzolana mixed with cement), is deposited on the convex surfaces  12   b  of elements  12  to form the roof of the building. Pillars  20  (only one is shown) are employed to prevent deflection of the elements during casting of the mixture. The pillars are removed after the concrete sets. The top surface  22  of the cement can be finished with colorful paints, or a layer of broken red brick may be added for insulation purposes. 
     It is to be understood that the present invention is not limited to the embodiment described above, but encompasses any and all embodiments within the scope of the following claims.