Project Topaz from the street corner: two storeys in white render with a timber-clad bay, a covered carport below the first floor, and a slatted gate and boundary wall with palms behind it.

Project Topaz

Accra · 2022

595 square metres in Accra, on a street where the houses sit close. There are neighbours hard against both flanks, and the plot meets the road along its front, where a wall and a slatted gate hold the line.

Nothing was standing on it. What existed was a set of drawings, and the work began by modifying those. That is a narrower brief than designing from nothing, and a stranger one: the decisions have been made once already, by somebody else, and the job is finding which of them will not survive being built. The house went up from the revised set, and the client came back four years later with Project Onyx.

Four things changed in the inherited set. The stair was rotated. A room came out of the ground floor so the living and dining could be one larger space. A washroom went in at ground level, so a visitor never has to go upstairs. And the master bedroom was reworked around a bigger bathroom and a walk-in closet.

Taking the room out is the change that needs defending, because houses here are usually described by their room count. What it buys is a ground floor that works as one space for the family living in it, which is worth more day to day than a door onto a room nobody uses.

Location
Accra, Ghana
Client
Richard Yentumi
Disciplines
Architecture, Interiors
Role
Design modification and interiors
Site area
595 m²
Status
Built 2022
The house from the approach: the glazed stair bay running the full height, the roof-level volume with a timber-faced canopy above it, planting in troughs along the first-floor edge, a car under the carport, and the boundary wall and slatted fence running along the pavement behind palms and clipped shrubs.
Two storeys and a roof level: lounge and living at ground, bedrooms and a family area above, and the first floor carried far enough forward to cover the parking without a separate structure for it.
The back porch: round columns down the open left side carrying the roof, full-height sliding glazed doors along the right into the dining area with a stone-clad wall beyond, woven chairs around small round tables on a polished floor, and a low white wall with roses and lawn past it.
The back porch: columns down the open side, sliding glazed doors running its full length into the dining area.
The living and dining space, with armchairs and a dining table in front of full-height curtained glazing and the kitchen island beyond.
Living and dining as one space.
The double-height lounge, with a dark timber media wall facing a corner sofa and glazing to the garden on both sides.
The lounge goes up through both floors and takes glazing on two sides, which is what stops a plan of ordinary rooms reading as a house of ordinary rooms.

What to notice

The external walls are 400 millimetres thick, composite, with the insulation outboard of the blockwork. The standard external wall in Ghana is a single leaf of sandcrete block at 150, uninsulated, with a split unit working against it for most of the year.

The thicker wall costs more to build and takes floor area nobody gets to stand in. What it buys is a slower house. Simulation work on insulated envelopes in tropical climates puts the cooling saving at roughly 20 per cent, and the build cost is paid once while the electricity is paid every month. This is written up in full in the note What a 400 millimetre wall costs.

Long section through the house, cut from the back porch through the dining and living areas to the stair, with a bedroom over and a roof terrace above that. Grid lines are numbered 1 to 6 across the top and floor-to-floor dimensions run down the right-hand side. Full size
Long section, cut from the back porch through the dining and living areas to the stair, with a bedroom over. Grid lines 1 to 6 run across the top and the dimension chain down the right adds to 10,975 overall.
The double-height living room seen past the dining table: a stair rising to an upper walkway, a slatted timber panel on the left and full-height glazing to the garden.
The stair rising to the upper walkway.
The roof level: a paved terrace with a timber pergola over loungers, dining tables under canvas umbrellas, and a white parapet closing the edge.
The roof level. The terrace exists because of a note on the drawing: waterproof screed laid to falls on the slab. A roof that sheds water is a roof you can put chairs on.

Where this stops being true

The 20 per cent is a simulation, not a bill. Nobody has measured this house against a version of itself built at 150 millimetres, and nobody is going to.

Accra’s day-to-night swing is about four or five degrees, and with that little range a heavy wall is not automatically an ally: it takes solar heat up through the afternoon, gives it back after dark, and has no cool night to lose it into. That is why the insulation sits outboard. It meets the sun, and the blockwork behind it is left to absorb what the household generates rather than what the sky does.

Where it stops is the glass. No wall thickness answers a window, least of all the lounge’s. If this house runs warm on an April afternoon, that is where to look first.