Multi-Storey Prefabs
Sustainable Innovation and versatility
By Dennis Ayemba
Prefabricated buildings are buildings made up of components manufactured in factories then assembled on site in a variety of arrangements. These buildings can be constructed using modular parts such as walls, frames, doors, ceilings, and windows, or a number of complete prefabricated modular building units.
Also read:Prefabricated Houses
The rise to prominence of prefabricated buildings can be dated back to 1945 after the Second World War. That was when the need for rapid construction of buildings arose to replace the buildings that were destroyed during the war. They were received well initially, but as time went by; they fell out of favor since some of them became less attractive aesthetically compared to traditionally built buildings.
Misconceptions
Even though prefabs are still popular in regions such as Asia and Europe where there are extreme weather conditions and a lot of seismic movements, in the developing world there exists a lot of disconnect with how people perceive alternative building technologies, key perceptions being: Prefabs are temporal structures and cannot be used to develop commercial multi-storey buildings, it is a cheap build and thus does not meet the perceived status associated with masonry works and due to the light weight they are not secure enough.
According to Warren Bott,National Sales & Marketing Manager for Worldwide Steel Buildings, Inc , during a purchase, the buyer should beware that majority of businesses do not manufacture their own product and are simply brokers.
He further added that the latest trends today are barndominium and Steel homes which are rapidly growing in the market due to the strength of steel and lack of maintenance required.
Worldwide Steel Buildings is a manufacture company that designs and manufactures steel buildings for all uses.They use a unique building design which uses a steel tube column making the interior and exterior finish flush that eliminates the required wind bracing and cord bracing in the walls that are very hard to finish around.
Resurgence of Interest
More recently there has been a resurgence of interest in prefabricated buildings mainly due to: A high demand for housing, relaxed legal regulations which acknowledge that prefabricated buildings can not only be aesthetically presentable but also be long lasting and sustainable. This has led to acceptance by the financing partners for mortgages, innovations and versatility that include a wide variety of sizes and configurations with sector specific building types, styles and options for variable plans and multi-storey configurations and also increased awareness with regards to availability of new and reliable technologies.
Recent significant examples in the international arena on the evolution of prefabricated buildings include the 30 storey Tower Hotel in Yue yang and B2 a 32 storey residential tower in Brooklyn; 60% of which was constructed off site.
The gap between prefabricated buildings and traditional buildings is narrowing significantly. There has been an increase in the number of firms who are involved in pre-fabricated buildings in Kenya to try and plug in the huge gap of 250,000 housing units annually. With diminishing land the only way to go is vertically by building multi-level buildings on smaller plinth areas.
According to Koto Housing Kenya who are manufacturer of Koto energy efficient building Expanded Polystyrene systems (EPS) panels, and one of the leading affordable building solution providers in Kenya; constructing multi-storey buildings in Africa is not as complicated as people may think. One only needs the right materials and expertise.
Koto Housing Kenya uses a building system of lightweight EPS panels that provide permanent formwork to reinforced concrete for columns and beam structures. The columns are produced by reinforcing and concrete filling vertical cores and horizontal beams in the KOTO panels. For Single Story Houses where there are little vertical forces, the structure need be designed for racking forces only. For this the columns are spaced apart in the external walls and a bond beam built into the panels across the top of the walls. The KOTO 8 panels serve as the walls between the columns and the bond beams also serve as anchorage.
For Multi-Level Construction the system is also designed as column and beam. The columns are produced by reinforcing and concreting all cores in the Koto 8 panels give continuous rows of columns, which are connected to concrete slabs. The columns carry the vertical loads and resist the racking forces in flexure. The concrete slabs serve the same purpose as beams. The KOTO 8 panels infill between the columns and together serves the purpose of walls.
Koto8 Panels Specifications
The KOTO8 panels are ideal for construction due to several unique specifications they possess: They are Energy Efficient Koto Forms hence reduce heating and cooling costs, they are fire tested in accordance to British Standards and ASTM, their standard and designer made forms assure very straight walls, they are certified Green products, they have a high strength tough mineral composite finishing plus Dead Load Weight, they possess a zero Spread of Flame, RC column and beam methodology, They are easy to use hence one can use unskilled labour, large volume output for large projects hence less cost to transport, they attract less labour cost to install, they are ideal for high Seismic and Cyclonic regions.
According to Mr. Peter Kinuthia the Technical Sales Executive at Koto Housing, they have in the recent past completed several multi storey projects in record time, with most recent ones being: 200 units for the National Police and prisons service at Kamulu and Migosi within six months as opposed to 3 years using conventional means.
“With these achievements and several other feats the misconceptions are slowly being broken and being a local manufacturer; we have the capacity to produce enough panels for 300 houses in a month as per demand. Therefore, we encourage Kenyans to adopt alternative building technologies,” he added.
