Building a Block of Flats in the UK: Cost and Planning Guide

The cost to build a block of flats depends on much more than the number of units. Gross internal area, storeys, structure, lifts, fire strategy, facade, services, specification, ground conditions, external works, location and programme can all move the construction cost materially.

A useful early budget separates the building works from the wider development cost. Land, finance, professional fees, planning obligations, utilities, abnormal works, contingency and VAT do not belong inside one unexplained £/m² figure.

If drawings are available, a measured estimate should test the actual floor areas, unit mix, common parts, specification and site information rather than relying on a national average.

How much does it cost to build a block of flats in the UK?

Published benchmarks are suitable for an early sense-check, not a tender or funding commitment.

Costmodelling’s detailed public cost table, published on 1 July 2026 and stated in the table at Tender Price Index 230, gives these broad UK building-only benchmarks:

• flats or apartments without lifts: about £1,850–£2,050/m²;
• flats or apartments with lifts: about £2,470–£2,730/m²;
• one-off, standard-quality apartments of three to five storeys: about £3,000–£3,320/m²;
• high-quality residential tower accommodation: about £3,990–£4,430/m².

The detailed table sets the rates at Tender Price Index 230, a UK regional factor of 100 and a building-works value factor of 1, which the source associates with building works of approximately £1 million. Costmodelling instructs users to apply the relevant project-value adjustment as well as regional and time adjustments. The figures include building preliminaries and contractor overhead and profit at the source’s stated allowance. They exclude external works, land, professional fees, VAT and client-supplied fittings, furnishings and equipment.

Those exclusions are substantial. A constrained urban site, basement, difficult ground, major utility reinforcement, complex facade, enhanced fire strategy, high services content or premium specification can move a scheme outside a broad benchmark quickly. London and other high-cost locations also require a regional adjustment.

Use the rates as a starting point only. Before relying on the budget, confirm:

• the measurement basis and gross internal area;
• location and tender date;
• unit mix and net-to-gross efficiency;
• height, storeys and structural form;
• lift numbers and specification;
• facade and roof design;
• fire, acoustic and building-services requirements;
• external works, drainage and utilities;
• abnormal ground or demolition;
• VAT and professional-fee treatment;
• contingency appropriate to the design stage.

Construction cost is not total development cost

A development appraisal should show the cost layers separately. Combining everything into one rate makes it difficult to see what has been allowed for and where the risk sits.

Building works

This is the main construction package: substructure, frame, upper floors, roof, facade, windows, internal partitions, finishes, fittings, services, lifts and common areas.

Preliminaries and contractor costs

Site management, welfare, temporary services, scaffold, cranes or hoists, security, logistics, testing, insurances and programme-related costs need a visible allowance. The effect is especially material on constrained sites and longer programmes.

Where a published benchmark already includes preliminaries or contractor overhead and profit, do not add the same allowance again without first removing or adjusting the source allowance.

External works and utilities

Roads, paths, parking, landscaping, fencing, external lighting, drainage, service connections, diversions and reinforcement can sit outside headline building rates.

Do not assume statutory undertakers can meet the programme or that the initial connection allowance covers reinforcement, easements, off-site work or temporary supplies.

Abnormal works

Demolition, contamination, made ground, groundwater, retaining structures, party-wall constraints, archaeology, flood measures and difficult access can alter both cost and programme.

These items should be based on surveys and design information where possible. A generic contingency is not a substitute for identifying an abnormal risk.

Professional and statutory costs

The wider budget may need allowances for architects, engineers, planning consultants, fire consultants, building control, warranty providers, surveys, legal work and other specialists.

Planning obligations and statutory charges can include Community Infrastructure Levy, Section 106 obligations, biodiversity net gain requirements and, where applicable, the Building Safety Levy. The position is scheme- and date-specific. Read Property Developer Cost Obligations for the current boundaries and official-source links.

Finance, sales and holding costs

Development finance, monitoring fees, interest, legal costs, sales or letting costs and holding periods sit outside normal building cost. They still affect whether the appraisal works.

Risk and contingency

Contingency should reflect what is not yet known. A feasibility budget based on outline information needs more caution than a coordinated tender pack supported by surveys, schedules and specifications.

Keep identified risks separate where possible. That makes it easier to reduce the allowance as information improves rather than carrying one unexplained percentage throughout the project.

What information is needed for a block-of-flats estimate?

The quality of the estimate depends on the quality and maturity of the information supplied.

Site and existing conditions

Provide the site address, topographical information, utilities records, ground investigation, contamination information, demolition scope, access constraints and relevant surveys.

Planning and design information

Useful documents include:

• location and site plans;
• floor plans, elevations and sections;
• accommodation and unit schedules;
• gross internal area and net saleable or lettable area;
• planning conditions and obligations known at the time;
• architectural specification or outline finish schedule;
• structural scheme;
• fire strategy;
• mechanical and electrical design information;
• lift requirements;
• external works and drainage proposals;
• sustainability, energy and acoustic requirements.

Procurement and programme

State the intended procurement route, design responsibility, tender date, construction start, target completion and any phasing or sectional-completion requirements.

A short or constrained programme can affect preliminaries, labour density, logistics, temporary works and procurement premiums.

Commercial basis

Confirm whether the estimate should include VAT, professional fees, contingency, inflation, finance, statutory obligations and client-direct items. Record the base date and location so later revisions can be compared on the same basis.

Cost drivers that commonly move a flats scheme

Net-to-gross efficiency

Corridors, stairs, lifts, risers, plant rooms, bin stores, cycle stores and entrance areas are necessary but do not become saleable apartment area. Two schemes with the same number of flats can therefore have very different gross internal areas and construction costs.

Height and structure

More storeys can change the frame, foundations, crane strategy, vertical distribution, facade access, fire provisions and programme. Repetition can improve efficiency, but height does not simply reduce the rate per unit.

Lifts

Lift numbers, capacity, travel, redundancy and finish affect capital cost, shaft arrangement, services and future maintenance. The building layout should not rely on an early generic allowance once the design develops.

Fire and life safety

Compartmentation, protected routes, smoke control, firefighting provisions, alarms, sprinklers where required, facade design and testing can materially affect the scheme. Fire requirements must be coordinated with the current design, building use, height and jurisdiction.

Mechanical and electrical services

Heating and hot-water strategy, ventilation, electrical capacity, landlord supplies, metering, access control, data, life-safety systems and renewable-energy requirements can form a significant part of the building cost.

Facade and specification

Brickwork, rainscreen, balconies, windows, acoustic performance, airtightness, internal finishes, kitchens, bathrooms and common-area quality all affect the rate. Describe the specification rather than relying on labels such as standard, mid-range or premium without defining them.

Ground and substructure

Poor ground, groundwater, nearby structures, party-wall constraints, retaining walls and service conflicts can alter the foundation and basement solution. Early site information reduces the amount that must be carried as risk.

Logistics and location

Restricted deliveries, limited storage, road closures, neighbour constraints, working-hour limits and urban lifting strategy affect preliminaries and programme. Regional labour and tender-market conditions also matter.

Development stages and cost decisions

Feasibility

At feasibility stage, test the site area, likely massing, unit mix, gross-to-net efficiency, planning position and broad construction approach. Keep land and finance separate from building cost.

Use the budget to identify what would make the scheme unviable, not to create false precision.

Planning

Update the budget as planning information, surveys and statutory obligations become clearer. Track changes to floor area, unit mix, facade, energy strategy, access and external works.

A planning approval can still contain conditions or obligations with material cost and programme effects.

Technical design

Replace broad allowances with measured quantities, specifications, schedules and coordinated design. Resolve structural, fire, acoustic, MEP, lift and external-work interfaces before tender where possible.

Pre-construction and tender

Issue a controlled tender pack and record clarifications. Compare returns on the same basis, including exclusions, preliminaries, design responsibility, programme and inflation assumptions.

A low headline tender may not be the lowest comparable cost once omissions and qualifications are reconciled.

Construction and change control

Keep the working budget aligned with instructed changes, design development, procurement movement and risk releases. The original estimate remains useful only if the current forecast records what has changed.

Handover and operation

Commissioning, certification, defects, warranties, information handover and operational setup require programme and cost allowances. Property management is a separate operational decision; it should not replace a complete construction close-out plan.

Higher-risk buildings in England

For projects in England, a building containing at least two residential units may be a higher-risk building during design and construction if it meets the statutory height or storey threshold: at least 18 metres or at least seven storeys.

The prescribed measurement method, exclusions and project circumstances matter. The design-and-construction definition is not identical to every other Building Safety Act definition.

Where the scheme may be in scope, confirm the current position early. Building-control approval, dutyholder arrangements, change control, information requirements and programme should not be treated as a late tender clarification.

Other UK jurisdictions have different building-control and safety regimes. Check the rules applying to the project’s location.

Building a block of flats FAQs

How much does it cost to build a block of flats in the UK?

A public cost table published on 1 July 2026 and stated at Tender Price Index 230 gives broad benchmarks of roughly £1,850–£2,050/m² for flats without lifts and £2,470–£2,730/m² for flats with lifts, with one-off or higher-quality schemes above those ranges. These are building-only guide figures before regional, time and project-value adjustments. They exclude external works, land, professional fees, VAT and client-supplied items.

What should be included in a block-of-flats cost plan?

Include the building works, preliminaries, external works, utilities, abnormal items, professional fees, statutory obligations, inflation, risk and contingency. Keep land, finance, sales and VAT treatment visible rather than hiding them inside the construction rate.

Are land, finance and professional fees included in build cost per m²?

Usually not. Published building rates often exclude land, finance, professional fees, statutory charges, VAT, external works and client-direct items. Check the basis before using any rate in an appraisal.

When is a block of flats a higher-risk building?

In England during design and construction, a building with at least two residential units may be higher risk if it is at least 18 metres high or has at least seven storeys, subject to the statutory measurement rules and exclusions. Confirm the current regime for the specific project and jurisdiction.

What drawings are needed for a measured estimate?

Provide current plans, elevations, sections, area and unit schedules, specification information, structural and MEP design where available, fire and lift requirements, external works, surveys and the intended programme. Missing information should be recorded as an assumption or allowance.