Building Contractor London
One written contract, one programme, one company answerable for the whole build. You hold the design, we hold the build and the paperwork around it.
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 London and the surrounding counties, which means a single company carries the job and a single company is answerable for it. If you want to find a builder for a smaller job, our builders in London page covers how to vet one. If you want one firm to hold the design as well as the build, see the design and build page. This page is about the contract in between: you hold the design, we hold the build.
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
- Programming around the Party Wall Act where the work affects a shared wall. You serve the notices as building owner, or your surveyor does. We give you the drawings and programme they need, work with the surveyors and build to any award
- 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.
- Registered electricians and Gas Safe registered engineers: notifiable electrical work is certified by the registered electrician under Part P or notified to building control, and any gas alteration is made by a Gas Safe registered engineer, with the 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: beam, padstones, installation and building control. The engineer's fee sits in the knock-through figure | £1,500 to £4,000 |
| Full knock-through | Wall removal, beam, engineer's fee, propping, making good | £2,500 to £6,500+ |
Two further costs belong in any contracted budget and are routinely forgotten: the professional fees, meaning the designer, the engineer, any party wall surveyor and building control, which on an extension typically add 15 to 20 per cent of the build cost, 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.
Where the contract ends: handover
A contracted project ends with practical completion, a snagging list worked through against the retention you hold, and a handover pack: the building control completion certificate, the electrical and gas certificates, the engineer's calculations and any party wall award. Our snagging page explains how retention and the rectification period work, and the building control page explains the certificate a buyer's solicitor will ask for. The party wall page covers the notices you serve before any of this starts.
George did a great job on our new bathroom. He is a really friendly and helpful guy and always ready to discuss any issues or concerns and come up with a sensible solution. Best of all, he works to budget and does not try and find…
I had a bathroom refit which I was very pleased with and I then went on to get my kitchen refitted as I was so happy with the way he worked. Even though I made a few changes to my original idea nothing bothered him and he worked his magic…
Built a new extension at rear of property. Laid foundations, drainage, raised floor, new roof and completed all fixtures and interior decoration. Also in 2015 completed patio in garden, steps around rear extension. He did a fantastic job…
FAQ
Frequently Asked Questions
What is the difference between a builder and a building contractor?
A builder carries out the work. A building contractor takes responsibility for the whole project: one contract, one programme, coordination of every trade and professional, building control, programming around any party wall notices you serve, site safety and the final sign-off. On small jobs the distinction rarely matters. On a refurbishment with structural work, a shared wall and months on site, it is the difference between a managed project and one you are managing yourself.
Do I need a written contract for domestic building work?
You should have one. A plain domestic building contract sets out the scope, the price, the start and completion dates, the payment stages, how variations are priced and what happens when something unforeseen is found. It protects both sides, and it is the single most effective way to prevent a dispute at the end. We are happy to work under a standard domestic contract form.
How should payments be staged on a building project?
Money should follow completed work. Payments tied to defined milestones, such as completion of structural work or first fix, protect you. A large deposit before anything happens does not. Long lead time materials such as steel, stone or joinery are a legitimate exception and should be itemised separately rather than hidden in a lump sum.
What is the difference between a building contractor and a design and build contractor?
Who holds the design. With a building contractor you appoint the architect or designer yourself, the drawings are yours, and the contractor prices and builds them under one contract. With design and build, the contractor also appoints the design team, so one contract covers design and construction. Building contracting suits a homeowner who already has drawings or wants a designer working only for them. Design and build suits one who wants a single point of responsibility from the start.
Are you structural engineers as well as contractors?
No. GS Renovation is a building contractor. Where a project touches structure we appoint an independent structural engineer to produce the calculations and specification, we build strictly to that design, and building control inspects and certifies the work. Keeping design and construction separate is a safeguard for you, not a limitation.
Will you work alongside my architect or my own structural engineer?
Yes, and it is common. We build to issued drawings and calculations, and we raise buildability points early rather than on site where they cost money. If you already have a professional team appointed, we slot in as the contractor. If you do not, we can appoint the engineer and coordinate the rest on your behalf.
Who is responsible for site safety on a domestic project?
Under CDM 2015 the client has duties, but on most domestic projects those duties pass to the contractor. As main contractor we take on planning, managing and monitoring the work safely, site welfare, and the safety of anyone on or passing the site. Where several contractors are involved, one must be appointed principal contractor.
What We Contract For
The Work Behind a Contracted Project
The individual services a contracted London project is usually made up of.
Related pages
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