It is the most asked question in Kenyan building, and the most folklore-answered. Somebody’s cousin built for thirty thousand a square metre; somebody else swears nothing finishes under sixty. Both are describing houses you have never seen, built in years that have passed, to specifications nobody stated. A real answer comes from a drawing: quantities measured off the geometry, priced at rates with a date on them. Here are two.
Two real houses, costed from their drawings
A 3-bedroom hip-roof bungalow of 145.6 m² prices at KES 5.21M – 6.63M. A 4-bedroom flat-roof maisonette of 229.1 m² over two storeys prices at KES 7.23M – 9.20M. Both numbers are elemental estimates produced from complete dimensioned drawing sets at July 2026 rates — every wall, slab and tile taken off the drawing and priced by element, mid-range finishes, each carrying its rates date and a ±10% band. They are not quotations; nobody has tendered. They are the honest arithmetic of two specific drawings, which is exactly what a folk rate is not.
Where the money goes
Read any bill of quantities top to bottom and the order of spend is the order of building: into the ground first, then up the walls and over the roof, then doors and windows, then the finishes you touch, then the services in the walls, then everything outside the house. Two lines are chronically underestimated. Openings — doors, windows, ironmongery — cost like furniture you cannot ever remove. And external works — boundary wall, gate, septic, paving — price by perimeter and site condition, not floor area, which is why they vanish from per-square-metre folklore and reappear as an emergency.
What moves the number most
- Finishes. The most elastic element in the bill. The same shell can be finished at two prices a million shillings apart — this is where you flex if the total frightens you, and where a quote quietly cheapens if you do not read it.
- The roof you choose. A hip roof buys timber and tile across the whole footprint; a flat roof buys concrete and waterproofing. They price differently at the same floor area, before taste enters it.
- Your soil and your slope. Substructure is the line your plot writes. Rock where you expected soil, black cotton that must be dug out, a metre of fall — all of it lands in the foundations.
- Wet rooms. Every bathroom multiplies plumbing, waterproofing, tiling and fittings. Three bedrooms with four bathrooms is a bigger bill than four bedrooms with two.
- The year you build. Cement, steel and labour move. An estimate without a rates date is not conservative or optimistic — it is expired.
The per-square-metre trap
Divide our two houses out and the folklore falls apart on its own. The bungalow lands at roughly KES 35,800 – 45,500 per square metre; the larger maisonette at roughly KES 31,600 – 40,200 — lower, because one foundation and one roof are serving two floors. Same engine, same rates, same month, same country. If a single rate cannot survive two houses costed side by side, it cannot survive yours. The rate per square metre is an output of a design — never an input to one.
How to budget like it is your money
- Budget the top of the band. If KES 6.63M is affordable, the bungalow is affordable. If only the bottom is, it is not — yet.
- Add what the estimate excludes. Land, professional fees, approvals, utility connections, furniture. The building estimate is the biggest number, not the whole number.
- Ring-fence the contingency. Treat it as unspent until the roof is on. On most Kenyan builds some of it gets spent; on well-drawn ones, less.
- Phase deliberately, not accidentally. A bungalow extends sideways; a maisonette must be designed for its upper floor at foundation time. Phasing is a drawing decision, not a site improvisation.
Get a number with your name on it
The honest sequence is brief, then plan, then the bill of quantities of that plan — rates dated, band admitted, elements itemised. Chimbuko attaches the cost plan to your own drawing in the Technical Pack, and you preview it watermarked before paying anything. From there you can tender it line by line and know when a quote is missing a wall. Build to a drawing and a dated number — not to a rumour with confidence.