Prefabricated housing in Kenya is gradually becoming more and more common as time goes by.
High rise buildings.
High rise commercial projects using Pre Engineered Steel structures are now coming up e.g opposite Nairobi Baptist Church next to City Mortuary, there is an upcoming building with the frame structure made of steel. Also, around Yaya in Hurlingham, there is a high rise structure with the supporting structure made of steel.
Most other high rise buildings in Nairobi are still using reinforced concrete for the structure. Reinforced concrete is concrete mixed with steel.
Pre engineered prefabricated buildings are mainly of a commercial nature.
The cost of pre engineered building frame is around kes 15,000 per m2, same as cost of reinforced concrete building. Commercial buildings have costs per m2 for complete buildings stretching all the way to es 60,000 per m2. This means that the structural component, whether pre engineered steel or reinforced concrete, is only 25% of the overall cost of construction. To make any significant savings, architectural design and cost engineering will need to be worked on for other building elements apart form supporting frame structure eg finishes, roof, windows, doors etc.
In Kenya, there are wooden, concrete, form concrete and sandwich steel type of prefabricated buildings.
The Judiciary recently did prefabs using wood. University of Nairobi also has wooden prefab student accommodation.
Wooden prefab buildings cost around kes 25000 per m2, slightly more expensive than normal stone buildings which can be constructed for same quality at same price.
Foam concrete prefab.
These are cement based wall panels and cost around kes 1800 per m2, more than the cost of stone walling with plaster which costs around kes 1500 per m2.
Steel sandwich panels.
These are mainly seen around the Chinese contractor offices where they are doing highways eg Thika road, Southern Bypass near Carnivore.
The cost of a house built using these steel sandwich is same as cost of a stone house.
These are cheap and low costing their country of manufacture, eg China. The cost of import duty, freight and road transport to Nairobi makes them to be same cost as stone houses . In China, these cost around kes 8,000 per m2 for a house. When they reach Kenya, this cost goes to around kes 25,000 per m2, same as for a stone house.
Prefab buildings usually have lower quality compared to stone houses. Their ability to keep buildings warm or cold when the weather is harsh is less than for a stone building.
Their ability to give perceived security is less than for stone buildings since intruders can easily remove the panel form the outside.
The ability to readily find labor and replacement material is low compare to stone whereby each hardware shop readily has repairing materials and local fundis have the technical know-how.
Developers who have recently sold buildings constructed using prefab methods have of late had to deal with occupants pressuring them to give them solutions on how to carry out repairs since the technical know-how is scarce and materials not easily and locally available.
Prefabricated buildings are usually an attempt to reduce labour costs in buildings. In developed countries, labour costs are high. In Australia , for instance, brick layers earn more than doctors. Prefabricated buildings in such countries will therefore bring the cost of construction down considerably.
In Kenya, the labour laws are not strict, hence construction labour is still low. A fundi is paid around kes 1000 per day to build a 15m2 wall, meaning cost per m2 for labour is kes 65. This is very low, hence most people preferring to use manual labour and construct with stone than using prefabricated materials. As the years progress and labour laws become strict, manual labour will become expensive and that’s when there will be a large switch to prefabrication as people look for cheaper ways to build their houses. Currently, labour costs are 20 to 30% of total building costs in Kenya.
In USA, labour costs are on average 50% of material costs.
With such high labour costs, it makes more sense to use prefab methods in USA than in Kenya for now until labor costs increase considerably as they will in due time.
Francis Gichuhi Kamau, Architect.
Francis Gichuhi Kamau, Architect.