Extension guide
Bungalow to mansion conversion in Kenya
The short answer: a bungalow to mansion conversion is not a single product, and this site does not publish one price for it. It means making a single-storey bungalow much larger on the same plot: usually by adding a storey, extending on the ground, or both.
The published figure for a full second storey is KES 5 million to 7.5 million at mid-range for 80–120 m², and KES 8 million to 12 million or more at a premium finish. The same guide summarises a 100 m² second storey at KES 5 million to 9.5 million.
What does a bungalow to mansion conversion mean?
People who search for a bungalow to mansion conversion in Kenya are usually standing in a single-storey house and want a much larger one without buying another plot. “Mansion” is not a defined size on this site. The cost guides use it for larger houses, such as a 4-bedroom maisonette or a villa, which are new-build figures. A conversion is an extension of the house you already have.
The detail, the full cost table and the renovation tiers sit on the house extension and renovation guide. This page is the decision in front of that table: go up, go out, or start again.
Can you add a floor to a bungalow?
The extension guide says yes, after a structural assessment. An architect and a structural engineer check whether the foundations, columns and walls can carry another floor. It says most Kenyan bungalows built to a standard specification can take one additional floor. Some need the foundations strengthened before that floor is added. Reinforcement and underpinning are costed separately from the storey itself. There is no published price for underpinning on its own.
| What the extension guide describes | Size | Published cost |
|---|---|---|
| Full second storey, mid-range | 80–120 m² | KES 5 million – 7.5 million |
| Full second storey, premium | 80–120 m² | KES 8 million – 12 million or more |
| Summary line for a second storey | About 100 m² | KES 5 million – 9.5 million |
| Structural assessment, mid-range scope | Before design | KES 40,000 – 80,000 |
| Structural assessment, wider scope | Before design | KES 80,000 – 150,000 |
The guide’s FAQ also states the assessment at KES 40,000–100,000. Both ranges are printed on that page. The cost table is based on Nairobi 2026 rates at a mid-range finish of KES 60,000–70,000 per m². It says Kiambu, Thika and Nakuru run about 5–10% lower, and Mombasa and the coast about 5–15% higher. Add the guide’s 15% contingency. Do not treat the table as a contractor’s price.
The guide calls a second storey the extension that adds the most floor area on the plot you already own, often two or more bedrooms and a master suite. It is also the one that depends entirely on the existing structure. If the assessment says the bungalow cannot carry the floor, the storey price above does not apply.
What if the house should stay on one floor?
A larger bungalow, still single-storey, is an extension on the ground. From the same guide:
- Rear extension, 25–40 m²: KES 1.5–2.5 million mid-range, KES 2.5–4 million premium. The card on that page summarises this type at KES 1.5–3.5 million. It is the usual way to enlarge a kitchen, add a dining room, or add a ground-floor bedroom.
- Side extension, 15–25 m²: KES 800,000–1.5 million mid-range, KES 1.5–2.5 million premium. The guide says the side setback is typically 1.5–3 metres from the boundary.
- Wrap-around, rear and side together, 50–80 m²: KES 3.5–5.5 million mid-range, KES 6–10 million premium.
A garage turned into a room, and a staff cottage, are smaller jobs on that page. They do not turn a bungalow into a two-storey house. Read them on the extension guide if that is the brief.
When is it better to demolish and rebuild?
The extension guide says extending is almost always cheaper per square metre than building new, because you keep the foundations, some walls, the service connections and the access onto the site. For most Kenyan bungalows built in the last 20–30 years, it says extending up or out is 25–40% cheaper than demolishing and rebuilding to the same total size.
The exception it names is a house in such poor condition that putting it right costs more than that saving. Cracks, a foundation that was never designed for an upper floor, or walls that cannot be tied into are reasons to stop and price a new house instead. The bungalow cost guide and the 4-bedroom maisonette cost guide are the new-build comparisons. A conversion figure and a new-build figure are not interchangeable.
Will the plot and the county allow it?
The extension guide says many 50 by 100 foot plots in Nairobi, Kiambu and Nakuru carry a bungalow that uses about 40–60% of the area the county already allows, so there is often room to go up or out inside the existing rules. That is a general observation on that page, not a ruling on your plot. Setbacks, coverage and the number of storeys are county matters, and they differ.
An extension needs BORAQS-stamped drawings and county development permission. The guide’s cost table prices architectural drawings and county approval at 5–8% of the build cost on a mid-range extension, and 3–5% on larger projects. The house plans page prices a different service, drawings only for a new plan, at 3% of the estimated construction cost. Use the line that matches the job. A conversation before either fee is the architect consultation: a free 10-minute fit call, or a Project Exploration Session from KES 20,000 for one hour, credited against design fees if you proceed within 90 days. VAT is excluded.
How long does a storey take?
From the extension guide, for a full second storey:
- Construction: 16–28 weeks, depending on the structure and the finishes.
- Drawings and county permission: a further 6–12 weeks before construction.
- First brief to handover: typically 6–10 months on a project that is managed.
A single-storey room addition is shorter on that page: 8–14 weeks of construction. The assessment sits in front of both.
What if you want a mansion-sized new house instead?
A new 4-bedroom maisonette is priced on its own guide, not as an add-on to a bungalow. Start with the cost of a 4-bedroom maisonette and the cost of building a house in Kenya. If the existing bungalow is a 3-bedroom house and the question is only what it cost to build, that answer is on the 3-bedroom cost guide.
Before you buy materials or accept a lump-sum quote, the extension guide says to get a bill of quantities. The BOQ generator can draft one from areas you enter. It is a draft until it is checked against drawings.
Questions
How much does a bungalow to mansion conversion cost in Kenya?
This site does not publish one price for a bungalow to mansion conversion. The house extension guide prices a full second storey of 80 to 120 square metres at KES 5 million to 7.5 million for a mid-range finish and KES 8 million to 12 million or more for a premium finish. The same guide summarises a 100 square metre second storey at KES 5 million to 9.5 million. Structural reinforcement and underpinning are extra, and the guide says to add a 15 percent contingency.
Can you add a floor to a bungalow in Kenya?
The extension guide says yes, after a structural assessment. A BORAQS-registered architect and a structural engineer have to check whether the foundations, columns and walls can carry another floor. It says most Kenyan bungalows built to standard specifications can take one additional floor, and that some need foundation strengthening first. The guide's cost table lists that assessment at KES 40,000 to 80,000 for a mid-range scope and KES 80,000 to 150,000 for a wider one. Its FAQ also states KES 40,000 to 100,000.
Is it cheaper to extend a bungalow or to demolish and rebuild?
The extension guide says that for most Kenyan bungalows built in the last 20 to 30 years, extending upward or outward is 25 to 40 percent cheaper than demolishing and rebuilding to the same total size, because the existing foundations, walls, services and site access are reused. It also says the exception is a building in such poor condition that the repair costs more than that saving. That is why the assessment comes before the decision.
How long does it take to add a storey to a bungalow in Kenya?
The extension guide says construction of a full second storey takes 16 to 28 weeks, depending on the structure and the finishes. Design and county approval add 6 to 12 weeks before construction. From the first brief to handover, it says a storey addition is typically 6 to 10 months on a well-managed project.
Do I need approval to convert a bungalow in Kenya?
The extension guide says extensions need BORAQS-stamped architectural drawings and county development permission. Its cost table prices architectural drawings and county approval at 5 to 8 percent of the build cost for a mid-range extension, and 3 to 5 percent on larger projects. A consultation is a separate, smaller step: a free 10-minute fit call, or a Project Exploration Session from KES 20,000.