Pricing
Home Extension & Renovations Costs Costs per m² (Good vs Excellent) — UK 2025
Last updated from source: 22 January 2025. All prices exclude VAT.
Source reference: Homebuilding — “How much does an extension cost in 2025?”
Single‑Storey Extension — Cost per m² (excl. VAT)
Quality Level Cost Range (£/m²) Typical Features
Good £2,500–£2,900/m² More complex footprint; 2.5m ceilings; better‑quality materials; aluminium‑timber composite windows; enhanced insulation.
Excellent £2,900–£3,300/m² Complex design features; 3m+ ceilings; high‑end materials; triple‑glazed aluminium; maximum insulation levels.
Benchmark: A typical 30m² kitchen extension would be £66,000–£99,000 + VAT (smaller projects often cost more per m² due to fixed costs) Depending on the location, you may need to allow for an additional 10% to 35% premium, reflecting factors such as delivery charges, parking and access restrictions, material costs, labour rates, and other site-specific considerations identified during the survey and proposal stage.
Two‑Storey Extension — Cost per m² (excl. VAT)
Quality Level Cost Range (£/m²) Notes
Good £2,400–£2,800/m² Often more cost‑effective per m² because foundations/roof costs are spread across two floors.
Excellent £2,800–£3,200/m² Premium finishes and design complexity increase rates.
Depending on the location, you may need to allow for an additional 10% to 35% premium, reflecting factors such as delivery charges, parking and access restrictions, material costs, labour rates, and other site-specific considerations identified during the survey and proposal stage.
Side Return Extension — Cost per m² (excl. VAT)
Quality Level Cost Range (£/m²) Notes
Good £3,100–£3,450/m² Tight access and stitching into existing structure add complexity and cost.
Excellent £3,450–£3,800/m² Higher‑end finishes and glazing; structural intricacies common on terraces.
Side returns typically start around £2,800–£3,100/m² at standard quality. London/South‑East projects commonly carry a +20–25% uplift on these base figures.
Depending on the location, you may need to allow for an additional 10% to 35% premium, reflecting factors such as delivery charges, parking and access restrictions, material costs, labour rates, and other site-specific considerations identified during the survey and proposal stage.
Conservatory Extension — Cost per m² (excl. VAT)
The source groups conservatories by type, not by quality labels. For clarity, we’ve mapped types to quality bands.
Mapped Quality (Type) Cost Range (£/m²) Notes
Good ≈ Complex uPVC designs (Victorian/Edwardian, L/P/T shapes) £2,200–£2,800/m² More complex shapes and frames than basic lean‑to.
Excellent ≈ Oak frame £3,500–£4,200/m² Premium frames and detailing; higher performing and longer‑lasting.
Basic uPVC lean‑to options are typically £1,800–£2,400/m² (standard quality). For conservatories in London/South‑East, allow +25–35% uplift. Depending on the location, you may need to allow for an additional 10% to 35% premium, reflecting factors such as delivery charges, parking and access restrictions, material costs, labour rates, and other site-specific considerations identified during the survey and proposal stage.
Important Notes
All figures exclude VAT. For most existing‑home projects, assume +20% VAT on labour and materials
Costs are per m² of new internal floor area and vary with design complexity, footprint, specification, site conditions, access, and build route.
Regional premiums: London and the South‑East frequently add ~25–35% overall; side‑return projects often show ~20–25% uplift; conservatories ~25–35%.
Build routes affect cost: DIY/self‑managed can reduce the rate; a main contractor will sit at the higher end, reflecting lower risk and full project management.
Smaller extensions can appear more expensive per m² because fixed costs (e.g., prelims, design, setup) are spread over fewer square metres.
What counts as “Good” vs “Excellent”?
Good: Moderately complex footprint, ~2.4m ceilings, quality materials, composite or aluminium windows/doors, above‑standard insulation.
Excellent: Complex architectural detailing, 2.5m+ ceilings, high‑end materials throughout, Premium glazing, maximised thermal performance and ROI
Adapted from: Homebuilding — “How much does an extension cost in 2025?”