One World Living Systems (OWLS) and its sister company, OWLS Ikhaya Systems, were organized to promote the most affordable, environmentally friendly, energy efficient, and durable housing systems available anywhere in the world. One World Living Systems has made a WISE choice in utilizing the 'AP Panel' method of construction.
There is a worldwide shortage of affordable, durable housing and the problem is rapidly becoming worse. The AP Panel system can be quickly and affordably implemented to meet the need for long lasting homes, commercial buildings, and many other types of structures.
As stated in the Federation of American Scientists report "Affordable, Safe Housing based on Expanded Polystyrene (EPS) Foam and Cementitious Coating", Housing plays a central role in improving the quality of people's lives in both developing and developed countries. Safe and affordable housing provides personal, social, and economic benefits. Most directly, housing contributes to the health and safety of individual inhabitants. Housing re-anchors the homeless in the community and mobilizes those traumatized by a disaster, impacts especially important in a post -conflict situation. Housing also offers families a platform for economic recovery and is a means of employment generation, requiring intensive unskilled labor and local capital investment.
AP Panel type systems have been used all over the world to construct durable and efficient housing and commercial structures. AP Panels are especially well suited for construction in high wind and earthquake prone regions of the world. AP Panels are extremely strong and have been designed to withstand hurricane force winds in excess of 200 miles per hour. AP Panels can also meet fire code ratings of 1 to 2 hours. In many areas of the world, residential structures are built primarily of wood materials which may develop rot or become homes for termites and rodents. AP Panels contain no wood, making AP Panel structures impervious to rot and pests. Wood construction is also incapable of withstanding fires, which may totally destroy the home or commercial structure. AP Panel construction is one of the most fire retardant construction methods available. Brick or masonry block is a commonly used building material, but when cost of materials, transportation of materials and labor costs are each considered, brick or masonry block construction is also an inefficient construction method. Brick or masonry block is a poor choice for building in earthquake prone regions due to lack of structural integrity during earthquakes. Even a small scale earthquake can damage a brick or masonry home or structure, making the structure uninhabitable. Structures that are built using the AP Panel method practically eliminate common structural survivability concerns.
AP Panel construction uses a polystyrene core material, embedded with galvanized steel mesh and finished with a cement or plaster face, making AP Panel structures the most durable construction method available to housing contractors. The AP Panels will not deteriorate due to moisture, sun exposure or tropical climates, provided that the AP Panels are properly installed and finished. Also, no wood products are used in AP Panel construction, making the AP Panels an excellent building material in areas where subterranean termite infestation may be prevalent. Also, the demand for timber is greatly reduced, making the AP Panel system an obvious choice for builders in ecologically sensitive areas.
AP Panel structures are visually indistinguishable from other common, less efficient building structures. The materials that are required to construct an entire AP Panel structure are readily available and inexpensive in most regions of the world, making AP Panel construction an extremely affordable building process.
A cost analysis study was undertaken in October 1995 to compare the cost of finished walls for five different sizes of residential buildings in Mexico. The AP Panel system was compared against red brick walls with typical columns and beams. The study concluded a cost savings of 42% to 48% by using the AP Panel system. The study also showed comparable structural soundness, although red brick construction could in no way equal to or surpass the AP Panel construction method when factoring in material costs, labor costs, structural survivability after a disaster, etc.
A well recognized authority on the wire panel system, Ved Varma, architect and urban planner of Denver, Colorado USA, quotes in his research on affordable housing:
"The ever increasing demand for affordable housing poses a major challenge for the authorities of developing nations. The large population explosion combined with the already existing deficiencies of housing stock have overwhelmed the authorities to an extent that planning housing needs for the next generations has become a difficult task. In the constant struggle to meet the affordable housing demands, such authorities are constantly searching for innovative ideas and appropriate new building technologies.
Currently there are several new building technologies, available in different parts of the world that are worth looking into as possible alternate systems for mass affordable housing. The wire panel technology has shown certain merits over brick or cement masonry construction.
The Wire Panel Technology currently stands as one of the most environmentally sound, structurally strong and economically efficient building systems of our times. Since introduction of this technology in the 1960s, there have been significant amounts of design improvements, and research and development, assuring an innovative building technology that brings hope for the authorities to meet the challenge of providing affordable mass housing, particularly for slum clearance projects in the urban areas. The Wire panel manufacturers have undertaken extensive and detailed performance test through reputed material testing laboratories for acceptance of the wire panel technology by code evaluation agencies and building departments. Some of these test and calculations include panel load bearing capacities, crushing and shear strengths, projectile impacts, wind and earthquake resistance, fire rating, thermal and acoustical performances.
The Wire Panel System refers to lightweight structural panels fabricated in the factory with 2 inch X 2 inch 14 gage galvanized steel welded wire mesh attached on each side of the chords of vertical Warren "truss" supports spaced at 6 inches intervals. These "trusses" are made out of low carbon 10 gauge cold drawn galvanized steel wires and are 5 inches wide. The webs and chords of the "truss" are factory welded or manually tied with wire rings to obtain a wire frame skeleton. A core of 4 inch thick, low density expanded polystyrene insulation is encapsulated in this frame.
These wire panels are shipped from the factory and assembled on the site for walls and roof and then covered with mechanically or manually applied cement plaster on both faces - to thickness of 1 inch on the walls and 2 inches on the floor or roof - resulting in a composite structure with finished wall thickness of 6 inches. The first floor or roof slab would have total finished thickness of 7 inches. The load bearing strength of the panel is derived from the vertical steel wire support "trusses", and the widths of cement plaster over the wire mesh along each face, which provides structural rigidity and shear resistance.
The wire panels are generally manufactured with width of 4 feet and varying lengths of 8 feet to 16 feet. A 4 ft X 8 ft panel weighs about 30 pounds (without plaster finishes). The panels, therefore, are lightweight and easy enough to be lifted manually to second floor roof level, allowing fast assembly time without the help of lifting cranes. In this method, plaster finish is applied after assembly of wire mesh panels.
From the weight point of view it would be interesting to compare the wire mesh to conventional construction. Let's consider the panels with finish plaster. Residential buildings in tropical regions are generally built with solid core 8-inch thick cement masonry blocks with cement plaster finish on both faces. A wall built with such masonry blocks, 12 feet long and with height of 9 feet, would have an approximate total weight of 11,500 pounds. On the other hand a wire system panel of same size but with 6 inches thickness, plaster finished on both faces and meeting certain building code performance requirements, would weigh approximately 2500 pounds. The wire panels are lightweight, provide a safe, secure shelter, yet tough enough to resist the specified wind and earthquake forces and able to handle the superimposed loads on the floor slabs.
This Wire Panel System technology allows construction of a load bearing structures of up to 2 stories, often without use of beams, lintels or columns. On high-rise structures with the reinforced concrete framework of beams and columns, the wall areas could easily be built with these wire panels in lieu of the heavy brick or cement masonry blocks, affording a significant reduction in the dead load of the wall system. The reduction of load would allow considerable savings in design of lighter structural frames and foundations. The manufacturer's claim that the composite wire panel system structures can easily be designed to resist wind load of 200 miles per hour and to meet the seismic zone 4 earthquake requirements under the Uniform Building Codes of USA.
In Liberty City, South Florida, a large number of framed residential homes were lost when Hurricane Andrew struck the area. Amazingly a group of 14 homes built with the wire panel system suffered no wall or roof structural damage. In 1990 the Concrete Construction magazine reported that during Hurricane Hugo, 200 houses in Puerto Rico, built with wire panel system, suffered no structural damage from winds of 195 miles per hour. During Hurricane Keith, of October 2000, the town of San Pedro in Belize experienced winds of 135 miles per hour, with gusts of 180 miles per hour for more than 18 hours. While 89 per cent of the structures in this area were damaged or destroyed, the houses and hotels built with wire panels suffered no structural damage except broken windows from flying debris.
During the June 1992 California earthquake (6.6 to 6.9 Richter scale intensity), 4 buildings, some over 24 feet in height, built with the wire panel technology, showed no structural damage. 'There was no sign of cracks or damage of any kind to the superstructure or foundation', reported B.S. Pannu, an independent California licensed engineer who evaluated the wire panel structures after the earthquake. The epicenter of this earthquake was about 60 to 70 miles from the buildings.
The additional advantage of this system in tropical regions is that it allows significantly improved comfort level of the building interiors. In urban areas of the tropics it is common practice to design buildings with reinforced concrete roof slabs. A 5 inch reinforced concrete slab with 2 inches of cement finish would have the heat thermal transmittance value "U" of 0.52 as compared to the wire panel with cement plaster finishes, "U" value of 0.07. This low thermal transmittance "U" value of the wire panels signifies and extremely comfortable living environment indoor. Also given the time lag of solar heat gain transmission of 6 to 7 hours in the normal concrete structures, the wire panel system would have the time lag of less than two hours - thus allowing the wire panel buildings to cool off rapidly in the early afternoons. Structures with cement or brick walls and concrete roofs become unbearably "hot boxes" radiating heat indoor in the evening hours especially when the family is ready for routine domestic activities.
The wire panel system can be designed for different fire ratings to meet local building codes. The cement-plastered surfaces of the wire panels require minimum maintenance. Fungus or termites do not affect the wire panel materials. The electrical conduits, water lines, plumbing and other utility services can be easily run in the panel by removing portions of the polystyrene. Cutting, sawing or patching of the panels does not require high-tech equipment or skilled labor. An entire house including the roof can be loaded manually and transported to the site on a lightweight flat bed trailer, and unloaded manually and erected by a small crew of locally trained personnel in a very short span of time. Curved walls, arches, domes, and angular walls can be built with ease, thus allowing a variety of architectural features.
The wire panel system has another great advantage from a structural point of view - it is a most forgiving structural system. During or after the wire panels have been assembled on site, walls and openings for doors and windows can easily be modified, relocated or changed on site without impacting the structural integrity of the building. This type of flexibility of changes is not readily available with masonry or concrete materials.
The cement plaster finished exterior and interior wall as well as roof surfaces of the wire panel buildings allow compatibility with the existing neighborhood structures, providing an aesthetically cohesive urban character of the development. If needed, the exterior wall surfaces could be finished with brick or stone veneers, stucco or decorative textures."
We greatly appreciate Mr. Varma's contributions in the field of wire panel systems, both in research and development. Ved Varma is a Colorado, USA, licensed architect, urban planner and development consultant. He wishes to share his experience and knowledge of wire panel technology and to further advance this innovative construction method, both for housing construction and for commercial development around the world. Mr. Varma is presently working on a publication "Building with Wire Technology in Tropical Climates". |
