How Much to Charge for a Building Job in 2026

What a building quote needs to include

A one-line "extension, £52,000" quote is the fastest way to lose a customer's trust the moment something changes on site. Cover these ten things and there's a clear answer for every question that comes up mid-build:

1. 1Business details and confirmation you carry public liability insurance suitable for a project of this size and value.
2. 2Customer name and site address, with access notes — scaffolding, skip/grab lorry position, parking for deliveries, and any shared access with neighbours.
3. 3A phased breakdown, not one lump sum: demolition & groundworks, structure (walls, steels, roof), first fix, second fix, finish — each priced and paid as its own stage.
4. 4What's explicitly excluded — kitchen units and appliances, decoration, garden reinstatement — so the customer isn't expecting a finished, furnished room for a shell-and-carcass price.
5. 5Building Control route (building notice or full plans) and who's paying the fee.
6. 6Structural engineer calculations for any steels, beams or openings, and who's supplying them.
7. 7Confirmation that a written Construction Phase Plan is in place under CDM 2015 — on a single-contractor job, this is now your legal duty, not the client's.
8. 8Programme in weeks and a start window, with a note on what a delayed Party Wall notice or planning condition does to that date.
9. 9Milestone payments tied to the phases above — never more deposit than covers materials for the next stage.
10. 10Guarantee period and what it covers (structural work vs finishing work often carry different terms).

Not every building job is priced the same way

Building work spans everything from a single-room reconfiguration to a full double-storey extension, and pricing it off one day rate either underprices the big jobs or overprices the small ones. Phase it, and know the legal duties that come with being the contractor — not just the trade.

Price by phase, not a flat day rate

As a working guide for 2026: an experienced general builder's day rate runs £180–£320, with a labourer adding roughly £120–£180 a day. A single-storey rear extension typically costs £2,000–£3,000/m² at mid-market specification, excluding kitchen supply, appliances and VAT. A two-storey extension runs £1,700–£2,800/m² — lower per m² than a single storey because the foundations and roof are shared across both floors, even though the total is higher. A dormer loft conversion shell is commonly £1,400–£2,200/m² before fit-out. London and the South East typically run 20–40% above the national average; regions like Belfast and parts of the North East, Wales and rural Northern Ireland tend to sit lowest. Break every job into the same phases — demolition & groundworks, structure, first fix, second fix, finish — and price each one on what it actually involves, not a single blended number.

The CDM 2015 paperwork most builders skip

The Construction (Design and Management) Regulations 2015 apply to every construction project in Great Britain — commercial or domestic, however small. On a domestic job with a single contractor, HSE's own guidance is explicit: the client's legal duties "normally pass to the contractor," who must take them on in addition to their own duties as contractor. On a multi-contractor job it's the principal contractor, unless the client has appointed a designer or architect who has agreed in writing to take the role of principal designer instead. Either way, on the domestic extension, loft conversion or structural alteration jobs a general builder quotes every week, those duties are almost always yours by default, not something you opt into.

The practical duty that catches out the most builders is the written construction phase plan. HSE requires one on every project — its own phrasing is that "small job doesn't mean no plan, it means an appropriately detailed plan" — and its published examples of the kind of work this covers read like a general builder's job list: kitchens, bathrooms, structural alterations, roofing, dormers, extensions and loft conversions. Formal notification to HSE via the F10 form is a separate, higher bar — it only applies once a project will run over 30 working days with more than 20 workers on site at any one time, or exceeds 500 person-days in total — and most single-contractor domestic jobs never reach it. But the construction phase plan itself is required regardless of whether notification is, and for most small builders it's the step that gets skipped entirely, not the one that gets judged too small to bother with.

Why this isn't just paperwork — a real 2026 case

Adam's Building Construction Ltd, a Bradford building firm, built a rear extension over an existing gas service pipe and boiler flue without relocating either — the flue ended up terminating inside the finished extension, exposing the family living there to the risk of a gas leak, fire, explosion or carbon monoxide poisoning. HSE had already served an Improvement Notice requiring the company to produce written construction phase plans for its work; the company failed to comply. At Leeds Magistrates' Court on 7 August 2026, the company was fined £10,000 plus £4,263 costs, and the director was personally fined £1,000 plus a £400 victim surcharge for failing to give HSE investigators the information they were legally required to provide. The HSE inspector's comment on the case was blunt: it was "a tragic accident waiting to happen," and the failure to properly plan the work could easily have had fatal consequences. The plan isn't a form for the file — it's the step where you're supposed to ask "what's actually running behind this wall before we build over it," and on this job, nobody did.

How to price the work

UK building costs vary by region, spec and access, but these are a fair starting point for 2026:

• Day rate £180–£320 for an experienced general builder, plus roughly £120–£180/day for a labourer.
• Single-storey extension: £2,000–£3,000/m² mid-market, excluding kitchen, appliances and VAT.
• Two-storey extension: £1,700–£2,800/m² — lower per m² thanks to shared foundations and roof, higher in total.
• Loft conversion (dormer) shell: £1,400–£2,200/m² before fit-out.
• Building Control: £500–£1,200 depending on route and local authority; structural engineer calculations £400–£800.
• London and the South East run 20–40% above the national average; regions further out tend to sit lowest.
• Written Construction Phase Plan & site risk assessment (CDM 2015): a small, fixed line — commonly £100–£250 for a domestic job — that belongs on every quote regardless of size.

A worked example

A single-storey rear extension, 4m x 6m (24m²), priced by phase the way described above, including the paperwork:

£51,230 for a 24m² single-storey rear extension shell through to finish — roughly £2,135/m², in line with 2026 mid-market rates — with the structural engineer's calculations, Building Control fee and a written Construction Phase Plan each priced as their own line rather than folded invisibly into the structure figure. The quote notes that, as the sole contractor on this job, the client's CDM 2015 duties transfer to the builder for the duration of the works, and that the plan will be reviewed and updated if the scope changes once the wall's opened up. 15% deposit to cover demolition and foundation materials, then four milestone payments tied to the phases above.

Five details that get building quotes accepted faster

• Break the price into phases, not one number. "£51,230 for a rear extension" invites price-shopping against a competitor's single figure. "£11,500 groundworks, £18,500 structure, £8,200 first fix..." shows exactly where the money goes and makes staged payments feel fair rather than arbitrary.
• State what's excluded as clearly as what's included. Kitchen supply, appliances, decoration and garden reinstatement are the classic gaps that turn into arguments at handover. One line each removes the argument before it starts.
• Name the Building Control route. "Building notice, fee £680, arranged by us" reads as someone who's done this before. Leaving it out reads as someone who hasn't thought about it yet.
• Put the construction phase plan on the quote, not just in a drawer. A line like "Written Construction Phase Plan & site risk assessment (CDM 2015) — £150" costs almost nothing to add, shows the customer you run a compliant site, and is the paperwork that would have caught a mis-routed gas pipe before the wall went up around it.
• State the guarantee and the payment schedule together. "10 years structural, 12 months on finishing work; 15% deposit, balance across four milestone payments" answers the two questions every customer is actually worried about — will it last, and how exposed am I if it doesn't finish.

The fastest way to do all of this

A one-room reconfiguration is quick enough to price from memory. A phased extension with eight separate lines, a structural engineer, a Building Control route and a CDM 2015 plan to account for is exactly where a rushed verbal number either buries the paperwork inside the structure figure or leaves it out completely — the same gap that turned into a £10,000 fine in Bradford.

This is what QuoteRocket is for. Describe the job in plain English — "24m² single-storey rear extension, phased from groundworks to finish, structural engineer and Building Control included" — and it turns that into a branded, itemised PDF quote in under a minute, with every phase, fee and compliance line kept separate and labelled. Your customer accepts it with one tap on their phone, and an accepted quote becomes an invoice in one click — so a milestone-payment job doesn't also mean four separate pieces of paper to get paid against.

Whichever way you produce the quote, the principles hold: price by phase rather than one lump sum, and put the construction phase plan on the quote as its own line — it's the cheapest, most visible way to show a customer you run a compliant site, and it's the law on every job you take on, not just the big ones.

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