Most people hire a builder for a home renovation project once or twice in their lives. The builder does it every few months. That gap in experience is where most of the problems come from, so it helps to know the order things happen in before the first person comes round to quote.
Who does what on a renovation
On a small job, like a bathroom refit or a new kitchen, the builder is usually the only person you deal with. Anything bigger brings in more people.
An architect or architectural designer draws the scheme and, where needed, makes the planning application. A structural engineer does the calculations for steel beams, new openings and foundations. Building control, either the council or a registered private inspector, checks the work against the Building Regulations at set stages. The builder, usually called the main contractor, builds it and brings in the specialist trades.
Some builders offer the drawings and engineering as part of the job. Others expect them to be done before they price. Ask which at the first meeting, because it changes what the quote covers.
The client has duties too
Since October 2023 the Building Regulations have had a section on “dutyholders”, and the client is one of them. For homeowners most of those duties pass to the builder, but the builder is also told to check you know about them first:
“A contractor must not start any building work unless satisfied that the client is aware of the duties owed by the client under all relevant requirements.”
Building Regulations 2010, regulation 11L(1)
In practice, a builder who knows the rules will talk you through building control, the party wall position and who is responsible for what before anything starts. If nobody mentions building control at all on a job that touches the structure, that’s worth noticing.
The trades that need to be registered
Most of the building trades in the UK aren’t licensed. Gas and electrics are the main exceptions.
Gas work is covered by the Gas Safety (Installation and Use) Regulations 1998. Regulation 3 starts with a general rule:
“No person shall carry out any work in relation to a gas fitting or gas storage vessel unless he is competent to do so.”
Gas Safety (Installation and Use) Regulations 1998, regulation 3(1)
Further down, the same regulation requires anyone doing gas work for a living to belong to a class of persons approved by the Health and Safety Executive. That’s the Gas Safe Register, which took over from CORGI in 2009. Paragraph 7 then adds a line you don’t often see in safety law: “No person shall falsely pretend to be a member of a class of persons required to be approved”. Pretending to be Gas Safe registered is an offence on its own, whether or not the work is any good.
Every Gas Safe engineer carries an ID card with a licence number and a list of the work they’re qualified for. A boiler, a hob and a gas fire are different categories. Check the card.
Electrics in a house fall under Part P of the Building Regulations, which came in on 1 January 2005:
“Reasonable provision shall be made in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury.”
Building Regulations 2010, Schedule 1, Part P1
New circuits, a new consumer unit and most electrical work in a bathroom are notifiable. A registered electrician on a scheme such as NICEIC or NAPIT can self-certify and gives you a certificate at the end. If the electrician isn’t registered, building control has to inspect it, which costs more and takes longer. Keep the certificate, because a buyer’s solicitor will ask for it.
Common renovation jobs and what they involve
New builds on small London plots are the biggest jobs a homeowner is likely to take on. Expect full planning, a party wall award or two, a CDM health and safety plan, and a year or more from the first drawing to moving in.
House extensions are the most common structural job. A rear or side return extension usually means new foundations, a steel beam over the opening into the old house and moving the kitchen, so the house is without one for some weeks. Many go up under permitted development. Building regulations apply either way.
Loft conversions depend on head height, which needs to be about 2.2 metres from the top of the ceiling joists to the underside of the ridge. They also change the fire escape route for the whole house, so the stairs and landings usually get fire doors and mains-wired smoke alarms, not just the new room.
A full refurbishment of a period house usually means rewiring, new plumbing and heating, replastering and new floors. That’s the job most likely to turn up surprises once the old finishes come off.
How the job usually runs
The first visit is a look at the house and a talk about what you want. Bring a rough budget. Without one, a builder can only guess at the specification.
Then drawings, planning if it’s needed, and the building regulations application. Structural calculations are usually needed before a builder can give a firm price on anything structural.
Then quotes. Three is the usual number, all pricing the same drawings. After that, a written contract and a start date. Good builders are often booked several weeks or months ahead, and long-lead items such as steel, windows and roof lanterns need ordering early.
On site, the order is roughly strip-out, structure, first fix of plumbing and electrics, plastering, second fix, then decorating and snagging. Building control visits at key stages, such as foundations, drainage and the structure, and issues a completion certificate at the end.
Budgeting
Most of the cost is labour and materials, but a fair amount isn’t building. Drawings, structural engineering, building control fees, party wall surveyors, skip licences and parking suspensions add up, and many quotes leave them out.
Old houses hide things. Rotten joists, lead water pipes and a chimney breast taken out downstairs with nothing holding up the one above all turn up regularly in London terraces. A contingency of 10% is fine on a newer house. On a Victorian or Edwardian house, 15 to 20% is more realistic.
Things to sort out in writing
Put the price, the scope, the payment stages and the programme in a written contract. For a homeowner, the JCT Homeowner contract or the RIBA Domestic Building Contract are both written for this.
Agree how changes will be priced before the work is done. Keep copies of invoices, drawings and certificates, and take photos of anything that gets covered up, like pipe runs and cables in walls. They’re useful the next time someone has to drill into that wall.
Plan around the dust and noise as well. Most London boroughs allow noisy work from 8am to 6pm on weekdays and on Saturday mornings. A kitchen or extension job usually means a few weeks of cooking somewhere else.
Before you sign
If you’re comparing several firms, there’s a separate guide on the questions to ask a builder before you hire them. The short version: look at finished work, ask what the quote leaves out, and don’t pay for work that hasn’t been done yet.
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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.