Building Contractor London

People use "builder" and "building contractor" interchangeably, but on a project of any size they describe two different arrangements. A jobbing builder does the work you point at. A building contractor takes responsibility for the whole job: the programme, the trades, the compliance, the paperwork and the outcome. GS Renovation Ltd works as the main contractor on domestic projects across Central and Greater London, which means a single company carries the job and a single company is answerable for it.

What a building contractor does that a jobbing builder does not

The difference is not skill, it is scope of responsibility. On a contracted project the following are ours to hold, not yours.

• One written contract and one point of accountability, rather than separate arrangements with six trades
• The programme: sequencing every trade so that work is not undone by the trade that follows
• Appointing and coordinating the structural engineer, and building to their issued calculations
• Notifying building control, arranging inspections and obtaining the completion sign-off
• Preparing your Party Wall Act notices where the work affects a shared wall, and coordinating with the surveyors. The Act puts the duty to serve on you as the building owner, so we prepare and you serve
• Materials procurement, deliveries, storage and waste removal within a live London street
• Site safety and welfare, and the duties that fall on the contractor rather than on you
• Snagging, certificates and the handover pack at the end

On smaller jobs that machinery is overkill and we say so. A single bathroom does not need a contract administrator. A whole-house refurbishment with structural work, a party wall and four months on site absolutely does.

Contracts, payments and programme

Every project should start with something written that both sides have read. For domestic work that usually means a plain building contract setting out the scope, the price, the start and finish dates, the payment stages, how variations are priced and what happens if something is found behind the wall that nobody could see. We are content to work under a client's own contract or a standard domestic form, and we will not object to one being used.

On payments, the principle worth insisting on with any contractor is that money follows completed work. Staged payments tied to defined milestones protect you, and a large deposit before anything has happened protects nobody but the builder. Materials with long lead times, such as steel, joinery or stone, are a legitimate exception and should be identified and itemised rather than folded into a lump sum.

Variations are the other place domestic projects unravel. A change to the scope should be priced and agreed in writing before it is carried out, not totted up and presented at the end. Our quotations state their exclusions and provisional sums plainly for the same reason: the number you are given should be the number you can plan around.

Who we coordinate on your behalf

Being the main contractor means holding the other professionals together. To be completely clear about our own role: GS Renovation is a building contractor. We are not structural engineers, architects or party wall surveyors. What we do is appoint them, work to what they issue and make sure their requirements actually make it onto site.

• Structural engineer: sizes beams, specifies padstones and issues the calculations for any structural opening. Appointed independently, and their design governs the build.
• Architect or designer: where a project needs drawings for planning, we work to them and flag buildability issues early rather than on site.
• Building control: notified before notifiable work starts, inspecting at the defined stages and issuing the completion certificate.
• Party wall surveyor: engaged where the Party Wall Act applies, which on a London terrace it very often does.
• Certified electricians and gas engineers: for Part P notifiable electrical work and any gas alteration, with certificates issued to you.
• Planning: where consent or a lawful development certificate is needed, we coordinate the application rather than assume it will be fine.

Contractor costs and project values in London

Contracted projects are quoted as a whole, from drawings and a survey, but the underlying rates are the same ones published across this site. These are the benchmarks a domestic contract in London is usually built from.

Project type	Basis	Typical London figure
Full refurbishment, mid-range	Per m² of internal floor area	£1,500 to £2,200 per m²
Full refurbishment, high end or structural	Per m², including structural openings and premium finishes	£2,500 to £3,500+ per m²
Single storey extension, standard finish	Per m² of new floor area	£2,000 to £2,800 per m²
Single storey extension, mid-range finish	Per m² of new floor area	£3,100 to £3,700 per m²
Structural opening with steel beam	Per opening, engineer's calculations and building control included	£1,500 to £4,000
Full knock-through	Wall removal, beam, engineer's fee, propping, making good	£2,500 to £6,500+

Indicative London ranges, MyBuilder and Checkatrade, 2026.

Two further costs belong in any contracted budget and are routinely forgotten: the professional fees, meaning the engineer, any party wall surveyor and building control, and a contingency. A contingency of around 10 to 15 per cent is realistic on a period property, where what is behind the plaster is genuinely unknown until it is opened up. Our budget and contingency guide explains how to set one.

Safety duties on domestic projects

Under the Construction (Design and Management) Regulations 2015, domestic projects carry duties too, and in most cases the client's duties pass to the contractor. On a single contractor project that means we take on the responsibilities for planning, managing and monitoring the work safely, for site welfare, and for the safety of everyone on site and everyone passing it. Where more than one contractor is involved, one has to be appointed principal contractor. It is a fair question to ask any firm quoting for your project, and a firm that cannot answer it is telling you something useful.