London building costs per square metre

You may be planning a bespoke new build or a high specification refurbishment. Or it may be a London basement or a major extension. Either way, understanding current building costs per square metre is essential for confident budgeting. NU Projects has updated this quantity surveying guide for 2026. The page’s established search history has been preserved.

NU publishes its own rates on the build cost calculator. They are set out by work type and by specification tier. There is no form in front of them. Those are broad cost planning benchmarks. They are not quotations. They have to be tested against the actual property, drawings and structure. Access, programme and specification have to be tested too.

What a rate per square metre actually covers

A benchmark rate is construction only. It excludes VAT, professional fees, furnishings and external works. That holds unless a project specific cost plan says otherwise. A basement shell rate never includes the fit out that goes into it afterwards.

It is also measured against an area. There are three different areas in play. One is the gross internal area of the whole house. Another is the new area you are adding. The third is the area actually being refurbished. Two rates that look far apart are often the same number. They are measured against different things. Ask which one before you compare.

Prime Central London cost premiums

The location ranges reflect more than the postcode. Prime properties frequently require superior materials, detailed craftsmanship and heritage expertise. They also require restricted access planning, stronger neighbour management and longer specialist procurement.

What does specification mean?

Standard specification

A controlled palette of dependable products, straightforward details and limited bespoke work. Standard does not mean poor quality. But it assumes fewer specialist systems and simpler coordination.

Mid to high specification

Better kitchens, bathrooms, lighting, services and finishes. Plus selected bespoke joinery and more detailed design coordination.

Prime specification

Rare materials, extensive bespoke joinery, specialist stone and metalwork. Advanced heating, cooling, lighting and security. Detailed restoration and a higher standard of site management and handover.

What cost per square metre does not tell you

• Whether structural steel, underpinning or temporary works are included.
• Whether the rate covers kitchens, sanitaryware, appliances and fitted joinery.
• Whether mechanical and electrical systems are basic or fully integrated.
• Whether the property is listed, occupied or subject to a licence to alter.
• Whether VAT, professional fees and statutory costs are included.
• Whether restricted hours, access, protection and neighbour requirements have been allowed.
• Whether the rate is measured against gross internal area. Or against new area, or the area being refurbished.

Why building costs change

Construction costs respond to labour availability, material pricing, energy and logistics. They also respond to regulation, demand and the complexity of individual projects. The 2021 and 2022 period proved a point. Lead times and supplier prices can change quickly. Those historic predictions should not be used as a current forecast. But the lessons remain valuable.

Current cost pressures to plan for

• Skilled labour availability, particularly for prime finishes and heritage work.
• Subcontractor prices that may be reviewed during a long design or approval period.
• Heating, cooling, ventilation, insulation and sustainability requirements.
• Planning, party wall, freeholder and building management costs.
• Imported stone, specialist ironmongery, bespoke lighting and custom manufacture.
• Long lead kitchens, glazing, joinery and mechanical equipment.
• Restricted London logistics, storage and waste removal.

Procurement lessons from earlier supply disruption

The correct response to changing markets is not panic buying. Nor is it an oversized blanket allowance. It is early design, package specific procurement and clear ownership of decisions.

• Identify long lead items during technical design.
• Obtain current supplier and specialist feedback before the cost plan is fixed.
• Separate firm prices from provisional allowances.
• Record quotation expiry dates and inflation assumptions.
• Approve samples and technical information before manufacture.
• Maintain appropriate alternatives without weakening the design.
• Track procurement against the construction programme.

How NU Projects estimates a project

NU combines benchmark information with the facts of the property. Our quantity surveying approach considers measured scope, surveys, design information and specification. It also considers access, programme and live specialist feedback.

• Layered cost breakdowns rather than one headline rate.
• Measured quantities and transparent assumptions.
• Current market feedback from relevant trades and suppliers.
• Risk allowances linked to identifiable project conditions.
• Provisional sums for genuinely unresolved packages.
• Cash flow forecasting across design, procurement and construction.
• Regular cost plan updates as decisions are made.

An example of how the same area changes cost

Take a 100 square metre rear extension with a simple structure and controlled specification. Now take the same area with specialist glazing, complex steelwork and a bespoke kitchen. Add stone flooring, underfloor heating, air conditioning and restricted access. These are different commercial propositions. The floor area is identical. The scope is not.

So early cost per square metre figures should be used to test feasibility. As the design develops, a measured project cost plan should replace them.

Professional fees, VAT and contingency

Architecture, interior design and structural engineering may sit outside a construction benchmark. So may mechanical and electrical design, and quantity surveying. Project management, party wall work and statutory approvals may too. VAT should also be shown clearly.

Contingency should reflect surveys, design maturity and property risk. It is not a spare budget for optional upgrades. It should not disguise incomplete information.

Prime refurbishment budgeting is covered in more detail elsewhere. Read How Much Does a High End Home Renovation Cost in London in 2026?.

Design and build or traditional tender?

The procurement route affects when construction knowledge enters the project. It also affects who coordinates cost, design and buildability. Design and build can identify risk earlier. Traditional tender can work well when the information is complete and responsibilities are clear.

A separate guide compares the two routes. Read Design and Build or Traditional Tender: Which Route Gives Homeowners More Cost Certainty?.

See the £1.25m Knightsbridge apartment renovation. It is a completed example of NU Projects’ residential delivery.

Frequently asked questions

What is the average building cost per square metre in London in 2026?

It depends on the project type and the specification. The spread between a straightforward loft and a prime basement shell is large. It runs to several times over. We publish our own rates for all eight work types, at three specification tiers. They are on the cost calculator. A project specific cost plan is still required.

Why are prime London costs higher?

Prime projects combine higher specifications with heritage constraints and restricted logistics. They also involve specialist trades, complex services and demanding management requirements.

Are professional fees included in cost per square metre?

Not automatically. Every benchmark must state its exclusions. Consultant fees, VAT, furnishings, external work and contingency are often separate.

How often should a cost plan be updated?

At key design stages. And whenever the scope, specification, programme or market information changes materially.

Replace ballpark figures with a proper cost plan

NU Projects provides an integrated route. It is for clients who want architecture and interiors aligned from the start. The same goes for quantity surveying and construction.

For a detailed, tailored budget, book a confidential consultation with NU Projects.

For an early project benchmark, use the NU Build Cost Calculator. For a measured project-specific plan, review our quantity surveying service.