Reinforced Concrete Villa Construction: From Foundation to Roof

A reinforced concrete villa of 150-200 m² usually takes 12-14 months including the permit, and larger villas 14-24 months. The reason is the concrete itself: every pour needs curing time, and each floor waits for the one below to gain strength. Below is the order in which a villa goes up, and what I check on site at each stage.

1. Design, soil survey and permit: 4-10 weeks

Everything starts with the soil investigation. Boreholes and lab tests give the bearing capacity, groundwater level and the soil class under TBDY 2018, Turkey's earthquake code. Foundation type and depth follow from that report. Inland from Şile we often find clay; near the streams around Ağva the water table can be high. Both change the foundation and waterproofing design.

Then come the architectural, structural, electrical and mechanical drawings, a contract with a licensed building inspection firm and the building permit from the municipality. Decisions rushed here tend to become expensive changes during the frame stage. Decide if you want a basement, a pool or a future extra floor before the drawings are finished.

2. Site set-up and excavation: 1-2 weeks

The plot is cleared, the building corners are set out by a surveyor and excavation begins. Depth is usually around 1-2 m, more with a basement. On sloping plots, the safety of the cut and any retaining walls are dealt with now. An open excavation left through wet weather collects water and softens the formation, so I prefer to dig close to the foundation pour date.

3. Foundation: 2-3 weeks

For houses the usual choice is a raft or strip foundation. The sequence is blinding concrete, waterproofing, rebar, formwork, inspection sign-off and the pour.

What I check at this stage:

• Concrete grade: the code minimum is C25; we use C30 or higher for houses, with B420C rebar.
• Cover: the gap between rebar and concrete surface must match the drawings, held with plastic spacers, not bits of stone or brick.
• Vibration: concrete placed without a vibrator leaves voids and leaves the steel unprotected.
• Samples: test specimens are taken from each pour and lab results go into the inspection file.

After the pour the concrete is kept moist for at least seven days. Left in hot sun or frost, the surface cracks.

4. Structural frame: 2-4 weeks per floor

Columns, shear walls, beams and slabs are formed, reinforced, inspected and poured. A two-storey villa goes through this cycle twice, three times with a basement. It is the longest and most important stage, because mistakes made here can't be fixed later.

The error I see most often is striking slab props too early. When formwork can come down depends on temperature and strength gain. Props pulled early to save time come back as sagging and cracked slabs. The second is missing stirrups, or stirrups spaced wider than drawn, at beam-column joints. That zone takes the most punishment in an earthquake.

The building inspection firm checks the reinforcement before every pour, and nothing is poured without their sign-off. My advice to owners: ask for photos of the rebar before each pour and keep them. Once the concrete is in, there is no way to see what's inside, and those photos are useful for years.

5. Roof: 2-4 weeks

Either the top slab becomes a flat roof terrace, or a pitched roof is built on it in timber or steel: structure, OSB or boarding, a waterproof membrane, battens and tiles or metal sheeting. Insulation goes either in the roof space or on the top slab. On this coast, with the poyraz wind and driving rain, ridges, eaves and chimney junctions need more care than on a sheltered inland site.

6. Walls, windows and external insulation: 4-6 weeks

External and internal walls are built in brick or aerated concrete block and window frames are fitted. Then comes the external insulation system: mineral wool or EPS/XPS boards glued and mechanically fixed, then mesh and render. Thickness is calculated to TS 825. Insulation has to run over the columns and beams too; otherwise they become cold bridges, with condensation and mould on the inside.

With a basement, the buried walls get a bituminous membrane, a protection board and a drainage pipe at the footing. In clay without drainage, water sits against the wall and eventually finds a way in, however good the membrane.

7. Services and finishing: 8-12 weeks

Electrics, plumbing, heating, plaster, screed, plasterboard, tiling, flooring, paint, kitchen and bathrooms. This is the longest single block of time, and how long it takes depends mostly on how well the trades are sequenced. Two checks that shouldn't be skipped: pressure-test pipes before they're buried in the screed, and waterproof and flood-test bathroom floors before tiling.

8. Exterior, landscaping and occupancy permit: 3-5 weeks

Cladding, garden walls, paths and planting. If the project includes a pool, digging it during the frame stage avoids bringing machinery and moving spoil twice. The last step is applying for the occupancy permit with the inspection firm's reports.

Total time by size

Villa size	Estimated time incl. permit
150-200 m²	12-14 months
200-350 m²	14-18 months
Over 350 m²	18-24 months

A basement, a sloping plot, a frame stage that falls in winter and design changes during construction all push these figures up.

Common questions

Can you build a concrete villa in winter?

Yes, with precautions for the pours. Below about 5°C fresh concrete is covered, an anti-freeze admixture may be used, and pours are postponed when frost is forecast. The easiest schedule puts the frame in spring and summer and the interior work in winter.

Can the layout change after the frame is finished?

Partition walls can move; structural elements can't. Touching columns, beams or shear walls means redoing the structural design and amending the permit.

Concrete or steel?

Both are safe when done properly. Concrete takes longer but has high thermal mass and every local builder knows it. Steel is faster but needs separate fire and corrosion protection.

If you're planning a concrete villa, commission the soil survey first. Once you have the report, the foundation type and whether a basement is sensible become clear, and only then can time and cost be estimated properly. More on the system on our reinforced concrete house page.