STRUCTURAL INSULATED PANEL HOUSING IN KENYA. 2013.
The first types of Structural Insulated Panel housing in Kenya were steel sandwich types. These are 2 metal plates with polystyrene sandwich in between for insulation purposes. These panels then interlock to form the wall and roof structure.
These can be seen at the Chinese company constructing Thika super highway offices opposite Warren concrete at Kasarani. Also, the road construction company constructing Namanga road at Kajiado have used such.
Another is the Oriented Strand Board type. Oriented Strand board is a material similar to ply wood that forms the external skin with the inside sandwich made from insulating material such as polystyrene.
There is also reinforced concrete panel ype of construction. This produces heavy panels which require cranes to hoist. There are currently in use at Ruiru at the Dhodia group warehouses. These are very strong and long lasting.
Fibre Cement Board.
National Housing Corporation is in the process of constructing a factory to produce these types of SIPs. A Chinese company along Mombasa road has been active of late in advertising for the sale of these boards.
Construction Cost Savings.
SIP panels only deal with the wall and roof elements of construction. A typical building has several elements namely, foundation, walling, roof, windows/doors, finishes, services eg plumbing/electrical works and external works such as septic tank, fence, gate. To achieve substantial savings, all these elements must be designed to save at least some % from the total cost. To achieve cost reduction, someone needs to do much more apart from only saving from the wall and roof elements.
Current wall cost comparison.
The SIPs available in the market cost approx. kes 1800 per m2 without transport and labour. Masonry wall costs kes 800 without transport and labour.
Each stone is approx. kes 60 and there are 12 stones in 1 m2.
Therefore, if the site is in a place where masonry stones are available, there will be savings if the stones are used compared to the SIP panels. On the other hand, areas which don’t have masonry stone eg Nyanza, North Eastern, Eastern provinces, the SIP panels would be a considerable option.
Natural quarry stone is the most durable, with a lifespan of 50 years. This can be seen in the numerous 50 to 100 year old bungalows constructed during the colonial period in Upper Hill, Kileleshwa and Kilimani areas OF Nairobi.
The SIP Panle durability depends on how thick the outer panel is. The thicker, the longer the durability.
The house dimensions needs to be designed in multiple lengths of 1.2m and heights of 2.4m. This is the standard length and with of the average panel. This ensures less cutting/wastage.
Francis Gichuhi Kamau, Architect.