Earthbag building currently being constructed at Kiserian, Nairobi.
Cost breakdown.
Foundation. 142 bags=kes 3,000.
Super structure walling.70m2 =kes 21,000
Roofing.kes 22,800.
Floor=kes 30,000
Doors. 2 No. @ kes 5000=kes 10,000
Windows. 2 No. @ kes 2,500=kes 5,000
Wall plaster. =kes 28,000.
Paint=kes 28,000.
Plumbing and electrical works=kes 20,000
TOTAL=KES 167,800.
Earthbag houses have walls made from polypropylene bags filled in with soil.
Cost of wall.
Cost of 1 bag of dimensions 850mm by 450mm by 100mm is kes 20. 12 bags make 1 m2. Cost of bags per m2 =12 x 20 =kes 240.
Cost of soil.
Assuming the soil is available on site for free, the costs will be only labour costs.
With Manual labour of kes 500 per day, a man can dig up 3m x 3m x 0.5m =4.5m3 volume per day.
One sack contains a volume of 0.7 x 0.45x 0.1=0.0315 m3 of soil.
One man can fill in 142 bags per day. At a cost of kes 500 daily, this works out to kes 3.50 per bag. For 1 m2 or 12 bags, this works out to kes 42 per m2.
Cost of earthbag walling per m2 is kes 240 plus kes 42=kes 282. Add miscellaneous to total kes 300 per m2.
This is the lowest cost possible for walling compared to stabilised cement blocks at kes 500 and stone at kes 1000 per m2.
A 30m2 bedsitter room, with 64m2 wall surface, will cost kes 19,200 for walling.
Advantages.
The thick walls are strong enough to carry heavy loads hence another storey can be added on top. Buildings such as Fort Jesus, standing till today after construction 500 years ago, have similar thick sized walls which support several storeys.
Its also easier to create indent patterns which can be infilled with glass blocks or glass plus LED lights to create interesting wall facades.
https://www.youtube.com/watch?v=VtMRiKMbQ2U
Earthbag construction project at Kiserian on a leased property.
30 degree roof pitch.
The round curvilinear room has a pitch of 30 degrees for roof. The roof surface area is 60m2. Asuming gauge 32 mabati roof at kes 300 per m2, the iron sheet cost is kes 18,000.
The truss length is 40m.Assuming 3 x2 cypress timber at kes 120 per meter, the cost is kes 4,800.
Total roof cost is kes 22,800.
The plinth area of the room is 32m2.
The cost per m2 for roof will be kes 760.
Roof pitch 5 degrees.
With a 5 degrees pitch, cost will be as below.
Roof surface. Assuming Mabati gauge 32 at kes 300 per m2, the area is 54m2.
Cost of roof surface will be kes 16,200.
Timber structure.
The length of the timber trusses will be 35 meters.
Cost of timber , assuming 3 x2 cypress timber section at a cost of kes 120 per meter, will be kes 4,200.
Total flat roof pitch cost will be kes 20,400.
Cost per m2 will be kes 640.
Comparison.
Flat roof is cheaper by kes 2,400.
This is 11.7 % cheaper.
The cost reduction quite small.
uPVC stands for unplasticised Poly Vinyl Chloride. This is a compound of chlorine, carbon and Hydrogen. The Hydrogen and Carbon elements are obtained from petroleum while the chlorine part is obtained from common salt. Unplasticised means that plasticisers that make the compound soft have not been added.
A large percentage of uPVC is consumed in the building industry, 55%. Its mainly used to make doors, windows, ceilings, floor finishes, plumbing accessories and roofs.
uPVC is very rigid and hard to bend, compared to PVC which is easier to bend and mostly used to make plumbing and drainage pipes.
Roofs.
uPVC roofs can be in form of slates as shown below.
The slates are joined in a similar fashion as the natural slate stone roofs.
The advantages are that they cost less, are lightweight and are aesthetically appealing.
Windows and doors.
These costs around kes 8000 per m2, same cost as basic steel casement windows in Kenya.
They can open as hung or sliding.
Floor finishes.
These have been around in Kenya for many years, with Dunlop floor tiles coming in as the most visible brand.
These cost around kes 400 per m2, which till today, is one of the lowest cost methods of floor finishes in Kenya.
These can be arranged in various patterns and colours to bring out beauty and style.
Ceilings.
PVC ceilings are around 4 years old into the Kenyan market. They are low cost and very aesthetically appealing compared to other types of ceilings. They are also water proof, hence not damaged or discoloured by roof leaks, like it happens on the other soft board types of ceilings.
These costs around kes 400 per m2, way below soft board ceilings costs in Kenya.
Francis Gichuhi Kamau, Architect.
info@a4architect.com
Available for Rent. Contact info@a4architect.com or call 0721410684 for more info.
