House Extension Cost in South Africa 2026: Side Return, Rear, Wrap-Around

Extension costs in South Africa have settled into clear bands after several volatile years. This 2026 guide gives realistic per-square-metre rates for the four most common formats, and the line items that trip up most homeowners.

2026 build rates per square metre

• Standard side return: R48,000 – R64,000/m²
• Rear extension (single-storey): R44,000 – R60,000/m²
• Wrap-around (L-shape): R50,000 – R68,000/m²
• Double-storey rear: R40,000 – R54,000/m² (lower per m² due to scale)
• Johannesburg premium: +15–25%
• Premium finishes (Crittall, large glazing, exposed steel): +20–40%

What's included at these rates

Above figures cover standard shell-and-core build with mid-spec kitchen/bathroom finishes, but exclude:

• Demolition of existing structures (R60,000 – R160,000 typical)
• Underpinning if foundations are inadequate (R300,000+)
• Neighbour Lateral Support Agreements (R36,000 – R80,000 per neighbour)
• Bespoke joinery and high-end appliances
• Landscaping and reinstatement

Design and professional fees

• Architect (full service SACAP 0–6): 8–12% of construction value
• Architect (planning + SANS / NBR only): 4–7%
• Structural engineer: 1.5–3%
• Planning fees and Local Authority Building Control: R30,000 – R80,000

Contingency

Allow 10–15% contingency on top of construction cost. Older buildings (pre-1940) routinely consume the full contingency on hidden defects: rotten timber, undersized foundations, asbestos.

Where money disappears unnoticed

• Steel cost increases between quote and build (lock prices in writing)
• Glazing upgrades (large sliders add R160,000–R500,000 quickly)
• Kitchen specification creep
• Reinstatement work to the existing house (re-plastering, re-decorating)

MCFAR provides structural engineering for extensions across South Africa. Send us your drawings for a fixed fee.

Frequently Asked Questions