There’s no licence to be a builder in the UK, and London has a huge number of building firms. Most are one or two people. A much smaller number employ enough staff to run several large jobs at once. Choosing between them starts with knowing which kind of firm suits the job, before comparing any prices.
That’s the same whether it’s a new build, a home renovation or a single extension. If the job needs planning permission, the drawings usually come first and the builder second.
London had its own building law
Building work in London has been regulated separately from the rest of the country for most of its history. After the Great Fire of 1666, the Rebuilding Act required new houses in the City to be built of brick or stone, not timber. The Building Act of 1774 went further and graded houses into “rates” by size and value, each with its own minimum wall thickness. A lot of the Georgian terraces in Islington and Bloomsbury were built to those rules.
The London Building Acts, enforced by district surveyors in each area, carried on into the twentieth century. Inner London only came under the national Building Regulations in 1986.
That history still shows up on site. Party walls in London terraces are often thick, solid brick and shared right up through the roof, which is one reason the Party Wall etc. Act 1996 was modelled on rules that had applied in London for a long time before it went national.
What kind of firm you’re hiring
Most London builders fall into a few types, and each suits different work.
| Type of firm | Typical work | Usually suits | Watch for |
|---|---|---|---|
| Sole trader or small team | Repairs, decorating, small bathrooms | Jobs under a few weeks | Little cover if they’re ill or busy |
| General builder (main contractor) | Extensions, lofts, refurbishments | Most structural house jobs | Who supervises when the owner isn’t there |
| Design and build firm | Drawings plus construction under one contract | Clients who want one point of responsibility | Less control over the detailed design |
| Specialist contractor | Basements, roofing, garden rooms | One type of job done often | Who coordinates the other trades |
| Larger contractor | New builds, blocks of flats, commercial | Jobs with a project manager and QS | Overheads built into the price |
None of these is better than the others in general. A sole trader is often the right choice for a bathroom and the wrong one for a basement.
Hiring trades separately
Some homeowners try to save money by hiring each trade directly: a bricklayer, then an electrician, then a plasterer. On a small job that can work. On anything structural, it puts the coordination on you.
The Building Regulations now say who should hold that role when more than one contractor is involved:
“Where there is more than one contractor, or it is reasonably foreseeable that more than one contractor will be working on a project, the client must appoint in writing— (a) a designer with control over the design work as the principal designer for the purposes of these Regulations, and (b) a contractor with control over the building work as the principal contractor for the purposes of these Regulations.”
Building Regulations 2010, regulation 11D(1)
For homeowners, the regulations fill in the gap if nobody is appointed: the contractor in control of the build is treated as the principal contractor. If you’re managing the trades yourself, it’s often unclear who that is, and building control will want to know who is responsible for compliance. Most people find it easier to have one main contractor who takes it on.
How money moves under your builder
Your builder pays the subcontractors, and that part of the chain runs under the Housing Grants, Construction and Regeneration Act 1996. Section 108 gives every party to a construction contract a fast way to settle disputes:
“A party to a construction contract has the right to refer a dispute arising under the contract for adjudication under a procedure complying with this section. For this purpose “dispute” includes any difference.”
Housing Grants, Construction and Regeneration Act 1996, section 108(1)
An adjudicator has to decide within 28 days of the referral, and the decision is binding until a court or arbitrator says otherwise. The courts sometimes call it “pay now, argue later”.
Homeowners living in the house are mostly outside these rules, so your own contract with the builder needs its own payment terms. But the electrician and the scaffolder working under your builder are inside them. A builder who’s in regular disputes with subcontractors is sometimes one that’s short of cash, and that usually turns up on site as people not arriving.
What to check about a London builder
Trade bodies help narrow the field. The Federation of Master Builders and TrustMark both check members before they join, and both have a complaints process. They’re a filter, not a guarantee.
Insurance should include public liability and, for anyone with staff, employers’ liability. Professional indemnity matters if the firm is doing the design as well.
Then look at finished work. Ask to see a job similar to yours, ideally one a year or two old. Look at the details nobody photographs: how the skirting meets the floor, whether tile joints line up at the corners, whether the paint lines along the ceiling are straight. There’s a fuller checklist for this in the builders near me guide.
Local knowledge across the boroughs
There are 32 London boroughs plus the City of London, and each has its own building control team, planning department, parking rules and licensing for skips and scaffolding.
Some of the differences are big. A large part of Westminster and Kensington and Chelsea is covered by conservation areas, so even replacing windows can need permission. Some outer boroughs have Article 4 directions that remove permitted development rights on whole estates. Parking suspension charges and notice periods vary a lot between councils.
The ground varies too. Much of north and central London sits on London clay, which shrinks in dry summers and swells in wet winters, especially near trees. Parts of south and east London are on gravels and alluvium near the Thames. A builder who’s worked locally will know which streets need deeper foundations before the engineer even visits.
Specialisations
Most London builders do residential work: extensions, loft conversions, refurbishments. Fewer do heritage work on listed buildings, which needs lime mortars, matching brick and listed building consent for most changes, including some internal ones.
Commercial work such as shop, office and restaurant fit-outs runs to a different set of rules: fire risk assessments, accessibility requirements, landlord’s consent and often night working. A good domestic builder isn’t automatically set up for it, and the reverse is also true.
What a realistic price looks like
London prices vary a lot by borough and specification, so treat these as rough. A standard single storey extension often comes out somewhere around £2,000 to £3,500 per square metre in London, before kitchen and finishes. A full refurbishment of a period house is often roughly £1,000 to £2,500 per square metre. High-end work and basements cost considerably more.
Workmanship guarantees are commonly one to ten years, depending on the firm and whether it’s backed by an insurance-based scheme. Ask what happens to the guarantee if the firm stops trading.
The order of the work matters as much as the price. There’s a step-by-step outline in this guide to a successful home renovation.
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Force Builders Ltd is a London building company (Companies House 07049787) delivering house extensions, loft conversions and full refurbishments across Greater London. See our projects or get in touch.