KENYAN HOUSING SECTOR-EFFECT OF NEW LOW COST CONSTRUCTION MATERIALS AND METHODS
Prefabricated houses are buildings that are pre-made in the factory and transported to the site where they are bolted up together to form a complete house.
Prefabricated panels are in wood, and Structural Insulated Panels.
Structural Insulated Panels [SIP] are divided into 3 major types
1.OSB fiber cement panels.
Oriented Strand Boards as the name suggests are made of wood chipping strands oriented to cross each other and held together by a glue. The 1.2 m by 2.4 m boards are placed on both outer sides with polyurethane insulation sandwiched in between.
The FOB price for a panel in China is USD 3[KES 270]. This translates to KES 135 per square meter.
A square meter of wall will require 2 boards on each side and the insulation material, bringing the cost to around KES 300 per square meter FOB China. Add 50% in freight and port charges to Nairobi, the price comes to around KES 450 per square meter. This slightly cheaper than than the usual machine –cut stones or Stabilized soil blocks [[KES 550 per square meter]we have in Kenya hence not a viable option to import.
2. Steel panels.
These are made of 2 steel sheets, 1.2m by 2.4 m ,one on each side, with an inner core of polyurethane insulating material.
SIPs are made of the outer skin material on both panel sides and an inner insulating core usually made of polyurethane.
In the recent times, OSB boards have slowly overtaken steel SIPs as the preferred choice of housing worldwide.
This is because steel prices are rising hence a higher cost.
A steel SIP panel in China costs KES 900 per square meter. Ad 50% of freight and port charges to bring this to KES 1350. This is definitely way too high compared to the stone walling and stabilized soil block [KES 550 per square meter]we currently have available in Kenya.
3. Fiber Cement Boards,
This is usually dimensioned as 1.2 m long by 2.4m height by 6 to 15 mm thickness.
The FOB price in China is between 9 to 15 USD[KES 800 TO 1400] per piece FOB China. This translates to approx. KES 400 per square meter.
Add 50% for freight and port charges, bringing it to KES 600 per square meter. This is slightly more expensive than the usual stone and stabilized soil blocks [KES 550 per square meter] we have in Kenya.
The National Housing Corporation is in the process of setting up a factory to produce Fiber Cement boards at Athi River in Kenya.
China is the largest and the most efficient manufacturer of these boards at KES 400 per square meter.
If the NHC production can beat this or remain at KES 400 per square meter, it will make a significant change in the construction industry since this will be KES 150 per square meter cheaper than the currently available option of machine cut or stabilized soil block walling.
ALTERNATIVE TO PREFABRICATED HOUSING-DIAMOND HOUSE TECHNOLOGY
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The benchmark of low construction cost is the local materials. For walling, the local materials[stone or stabilised soil blocks] costs KES 550 per square meter. Any material that effectively brings the cost lower than this is termed as low cost.
Prefabricated housing is limited to only the walls and roofs which constitute 30% of the total construction costs. Holstic solutions that reduce costs in all the elements of construction starting from Foundation to walling, roofing, doors&windows,and finishes offers the most effective solution to construction cost reduction.
The DIAMOND HOUSE technology utilizes over 10 years of research in this holistic approach to cost reduction.
Any importation of prefabricated house panels will definitely be more expensive than what we currently have at the market.
Therefore, the solution to low cost housing in Kenya can only be achieved by utilizing local materials with creative technology. Another solution is to go the NHC way and manufacture the boards here in Kenya. Given the current high production rates in Kenya[energy,transport,labour], it remains a wait and see situation to whether NHC will be able to produce at KES 400 per square meter or less, hence replacing the current masonry stone and stabilized soil block walling which costs KES 550 per square meter to construct.
The DIAMOND HOUSE technology utilizes a holistic approach in reduction of construction costs by targeting 3 main areas
1. Creative use of construction technology.
2. 2. Use of phased residential house construction
3. Use of labour-based construction procurement method.
These are outlined here in more detail
By emphasizing on all the above factors, the DIAMOND HOUSE technology effectively reduces construction cost of residential houses by a minimum of 32%.
The DIAMOND HOUSE technology uses locally available materials e.g masonry stone walling or stabilized soil blocks for walling, GCI roofing sheets for roof and locally produced doors and windows hence the ability to be constructed everywhere even in the most remotest part of Kenya since these materials are available in any hardware.
The cost of obtaining the DIAMOND HOUSE technology is broken down here
Architect Francis Gichuhi Kamau