Extension cost estimator
Built around how Maven Design & Build prices work in and around London: £1,600 per m² + VAT for the build package (labour included for finishing fit-out; finishing materials listed separately), plus an indicative programme to handover. Compare with typical average and premium market rates, then WhatsApp or call us for a clearer figure on your home.
Used only for the materials add-on (doors, windows, skirtings, internal doors, flooring).
Maven Design & Build — London & surrounds
Our build rate: £1,600 / m² + VAT
1. Build package (Maven rate)
£48,000 inc VAT
£40,000 ex VAT (25 × £1,600)
Includes labour and construction for the extension / conversion, including labour to fit finishing items. Excludes supply of finishing materials: external doors & windows, skirtings, internal doors, and flooring.
2. Finishing materials (separate)
£8,400 – £12,600 inc VAT
£7,000 – £10,500 ex VAT · mid-range finishes
Estimated supply cost for doors, windows, skirtings, internal doors and flooring. You can supply your own or we can source to your specification — labour to fit is already in the Maven rate above.
3. Everything included (estimate)
£56,400 – £60,600 inc VAT
Maven build package + finishing materials (mid-range finishes)
Estimated duration
Build to handover: ~12–16 weeks
Full programme (design, approvals / PD checks, then build to handover): typically ~18–30 weeks, depending on planning route and site conditions.
How this compares in London
- Typical average all-in market rates: ~£2,200–£3,200/m² + VATFor 25 sqm ≈ £66,000–£96,000 inc VAT
- Premium London market rates: ~£3,200–£4,800/m² + VATFor 25 sqm ≈ £96,000–£144,000 inc VAT
- Maven Design & Build: £1,600/m² + VAT for the build package (finishing materials listed separately) — clear, competitive pricing for quality delivery in and around London.
Disclaimer: Indicative only — not a fixed quote. Ground conditions, structural steel, drainage, party wall, planning fees and unusual access can change cost and programme. VAT shown at 20%.
Need a clearer figure for your home?
Get in touch and we will talk through your plans, finishes and programme — WhatsApp, call, or book a consultation.
Or message us anytime on WhatsApp: open chat.