Renovation Cost Per Square Metre: A Realistic UK Benchmark

Cost per square metre is one of the most commonly quoted renovation statistics, and one of the most commonly misunderstood. It's a genuinely useful way to size up a project early on — but treating it as a quote, rather than a starting point, is how a lot of renovation budgets go wrong before they've even begun.

What cost per square metre actually measures

It's simply the total project cost divided by the floor area affected. That simplicity is both the appeal and the limitation — it compresses everything (labour, materials, specification level, structural complexity) into one number, which means two projects with the same £/m² figure can look identical on paper and be completely different in reality.

Realistic UK benchmarks

These are broad, genuinely typical ranges as of writing, not a quote for any specific project — actual cost depends heavily on specification, access, and existing condition.

• Light refurbishment (decoration, minor updates, no structural work): roughly £300–£700 per square metre.
• Full renovation of an existing room (new flooring, full redecoration, some fixtures): roughly £800–£1,500 per square metre.
• Single-storey extension, shell only: roughly £1,800–£2,500 per square metre.
• Single-storey extension, including fit-out: roughly £2,500–£3,500+ per square metre.
• Loft conversion: roughly £1,800–£2,800 per square metre, though this type of project is unusually sensitive to roof type and structural work, so the range is wide.

For room-specific costs that don't reduce neatly to a per-square-metre figure — bathrooms and kitchens especially, where fixtures dominate the cost far more than floor area — see our bathroom renovation cost guide and our full renovation budgeting guide.

Why the same figure can mean different things

A small, complex room (a bathroom, with waterproofing, tiling, and plumbing packed into a few square metres) will often show a much higher £/m² figure than a large, simple room, even though the bathroom might cost less in total. This is why per-square-metre figures are most useful for comparing similar project types, and much less useful for comparing across very different ones. See our full guide on tiling costs for how much of a small bathroom's cost sits in preparation and waterproofing rather than floor area.

A worked example: sizing up two different projects

A 20m² single-storey extension at a shell-only rate of £2,000/m² gives a rough early estimate of £40,000 before fit-out. A 6m² bathroom renovation, even though it's a much smaller area, can land at £1,500-£4,500 total (see our tiling cost guide for where much of that goes) — which works out to a far higher effective £/m² than the extension, despite being the smaller, "simpler-sounding" project. This is the exact trap the figure sets if used without context: comparing an extension's shell rate to a bathroom's all-in rate isn't a like-for-like comparison, even though both are expressed the same way.

More room types, for early sizing

• Kitchen (units, appliances, flooring, decoration): because units and appliances dominate cost rather than floor area, a small kitchen with a high specification can have a much higher £/m² figure than a larger kitchen at a standard specification.
• Garden room or outbuilding: generally lower £/m² than a house extension, since there's no existing structure to tie into and typically simpler foundations, though this varies with insulation standard and services.
• Loft conversion with an en-suite: pushes toward the top of the loft conversion range, since a small en-suite adds bathroom-level cost density (waterproofing, plumbing) into what's otherwise a simpler space conversion.

Why quoted figures vary so widely between sources

Beyond genuine regional and specification differences, a lot of the variation in published £/m² figures comes down to scope: whether the figure is shell-only or includes a full fit-out, whether it includes professional fees and building control costs, and whether VAT is included. Always check what's actually covered before comparing two figures from different sources — see our guide on comparing renovation quotes properly for the same principle applied to real quotes.

Using it sensibly

Cost per square metre is genuinely useful for one thing: getting a rough sense of scale early on, before you're ready to get proper quotes. It's not useful for comparing very different room types, and it should never be treated as a substitute for an itemised quote based on your property's actual condition and your chosen specification.