Choosing the right refurbishment company is the single most important decision in any London project, more important than the design or the budget, because the best contractor delivers a sound result at a fair price while the wrong one delivers stress, overruns and remedial bills. Yet most people choose on price alone and find out too late what they bought. This guide sets out exactly what to check before you hire, the red flags that should end a conversation immediately, and the questions that separate a professional contractor from a risk.
What to check before you hire
A handful of checks, done before you sign anything, filter out most of the contractors who cause trouble, and a genuine professional will welcome every one of them.
Start with insurance: ask for evidence of public liability cover (£2 million or more is standard) and, where they employ staff, employers' liability. A contractor without current public liability is a contractor whose mistakes become your problem. Next, references and recent work: ask for two or three projects of similar scope and, ideally, speak to those clients or see the work in person. A real track record is easy for a good firm to produce and impossible for a bad one to fake.
Look for a written, itemised quotation rather than a single headline figure, so you can see what is and is not included and compare like with like. Confirm they work to a written contract. Check for relevant accreditations and competence for any specialist element, particularly electrical certification (NICEIC or equivalent), gas (Gas Safe), and fire-safety competence if your project involves HMO or fire works.
Finally, check how they handle guarantees: a confident contractor stands behind their work in writing. The table summarises the core checklist.
Check
What to look for
Public liability insurance
£2m+, current, evidenced
References / recent work
2–3 similar projects, seen or spoken to
Written itemised quotation
Clear inclusions and exclusions
Written contract
Scope, payment stages, dates
Electrical certification
NICEIC / NAPIT registered
Gas work
Gas Safe registered
Fire / HMO competence
Relevant for fire and HMO works
Written guarantee
Workmanship guarantee in writing
Written quotes and contracts: insist on both
The documents you agree before work starts are what protect you when something goes wrong, and the absence of them is the common thread in almost every refurbishment that ends badly.
A proper quotation is itemised: it lists the works, the specification, the inclusions and, just as importantly, the exclusions and any provisional sums. This lets you compare contractors fairly and removes the ambiguity that later becomes a dispute. Beware the single-figure quote with no breakdown; it tells you nothing and commits the contractor to nothing.
A written contract then sets out the scope, the price, the payment stages tied to progress, the start and completion dates, how variations are priced, and what happens if things change. It need not be elaborate, a clear written agreement is enough for most domestic work, but it must exist. Verbal agreements are unenforceable in practice and invite the slow scope-creep and surprise charges that wreck budgets.
Pay against progress, never far ahead of it. A sensible structure is a modest deposit, then staged payments as defined milestones are reached, with a retention held until snagging is complete. This keeps the contractor's incentives aligned with finishing your job properly, which is exactly where you want them.
Compliance competence for HMO and fire works
If your project touches fire safety, an HMO, or compliance-critical work, ordinary building competence is not enough, and this is the area where the wrong contractor does the most dangerous harm because the failures are invisible until a fire.
Fire doors illustrate the point. A fire door's rating depends on the leaf, the frame, the gaps, the intumescent seals and the ironmongery all being correct together; an FD30 leaf hung carelessly in the wrong frame is not a fire door at all, however it looks. Fire-stopping must use tested products matched to each penetration, not general expanding foam. Alarm and emergency lighting systems must be installed and certified to the relevant British Standards. None of this is something to learn on your job.
So if your refurbishment involves an HMO, a converted block, or any fire-safety element, ask specifically about the contractor's competence in this area: third-party certificated fire door installation, knowledge of the relevant standards, and the certification and photographic evidence they provide on completion. A contractor who treats compliance paperwork as part of the job, rather than an afterthought, is the one to trust.
This is core to how Apex London works, combining refurbishment with genuine fire-safety and HMO-compliance competence under one roof, so the safety-critical work is done right and documented.
Red flags that should end the conversation
Some warning signs are serious enough that the right response is to walk away, no matter how attractive the price. Recognising them early saves money and misery.
Cash-only is the clearest. A contractor who insists on cash and will not provide a proper invoice is avoiding tax, almost certainly uninsured, and leaves you with no record and no recourse. A large upfront deposit is the next: a request for a big percentage of the total before any work begins, or before materials are even ordered, is a classic sign of a contractor using your money to fund another job, or worse. A modest deposit is normal; half the contract value up front is not.
No written contract, or reluctance to put anything in writing, tells you the contractor wants the freedom to change the deal as they go. No verifiable references, no insurance evidence, and a vague or evasive answer to direct questions about qualifications are all reasons to stop.
High-pressure tactics, a price that is only available today, or a quote dramatically below every other, also signal trouble; the lowest quote almost always hides exclusions that reappear as extras. Trust your instinct: if a contractor is evasive before they have your money, they will be far worse once they have it.
Questions to ask every contractor
A short list of direct questions, asked of every contractor you consider, reveals more than any brochure, because the quality of the answers, and the willingness to answer at all, tells you who you are dealing with.
Ask: Are you fully insured, and can I see your public liability certificate? Can you show me two or three recent projects like mine, and may I speak to those clients? Will you provide a written, itemised quotation and work to a written contract? What are the payment stages, and how much is the deposit? Who exactly will be on site, your own team or subcontractors, and who manages the job day to day?
Then the project-specific ones: How long will my project take, and what could delay it? What happens if you find a problem once work starts, how are extras priced and agreed? What guarantee do you offer on your workmanship, and is it in writing? For compliance work, ask how the electrical, gas or fire elements are certificated and what evidence you receive at the end.
A confident, competent contractor answers all of these readily and in plain language. Hesitation, vagueness or irritation at being asked is itself the answer. The contractor you want is the one who has clearly been asked these questions before and is glad you asked.
Why one accountable contractor beats a chain of trades
A recurring choice in refurbishment is whether to appoint one contractor for the whole project or to assemble and manage the trades yourself, and for most owners the single accountable contractor is the safer and ultimately cheaper route.
Managing trades yourself looks cheaper on paper, but it makes you the project manager, responsible for sequencing, for the gaps between trades, and for the arguments when one trade's work affects another's. When something goes wrong at an interface, the plumber's leak that damages the plasterer's ceiling, you own the dispute, because no single party is accountable for the whole.
A single contractor carries that accountability. One survey, one quote, one programme, one point of responsibility if anything is missed, and one party to hold to the guarantee. The trades are sequenced by someone whose job it is to keep them moving, which removes the dead time that piecemeal projects bleed.
This matters most exactly where the risks are highest, at the interfaces between trades and on the concealed, compliance-critical work that only shows its quality years later. The contractor you choose should be one who takes responsibility for the whole result, not just their own slice of it. For a fully itemised quotation and a single point of accountability across your London refurbishment, call 020 3962 0455.
Frequently Asked Questions
How do I choose a good refurbishment company in London?
Check current public liability insurance (£2m+), ask for and follow up two or three references on similar projects, insist on a written itemised quotation and a written contract, confirm relevant certifications (NICEIC, Gas Safe, fire competence for HMO work), and ask for a written workmanship guarantee. Choose on overall value and accountability, not the lowest price.
What are the red flags when hiring a builder in London?
Cash-only with no proper invoice, a large upfront deposit before work or materials, no written contract, no verifiable references or insurance evidence, high-pressure today-only pricing, and a quote dramatically below all others (which usually hides exclusions). Evasiveness about qualifications or insurance is reason enough to walk away.
How much deposit should I pay a refurbishment contractor?
A modest deposit is normal, often enough to cover initial materials, but you should never pay a large share of the contract value before work begins. Pay against progress through staged payments tied to defined milestones, and hold a retention until snagging is complete, so the contractor's incentive is to finish your job properly.
Should I hire one contractor or manage trades myself?
For most owners, one accountable contractor is safer and ultimately cheaper. Managing trades yourself makes you responsible for sequencing, the gaps between trades and any disputes at the interfaces. A single contractor gives you one survey, one quote, one programme and one party to hold to the guarantee, especially valuable on compliance-critical work.
What insurance should a refurbishment company have?
At minimum, current public liability insurance of £2 million or more, evidenced by a certificate, and employers' liability insurance where they employ staff. For specialist work, look also for electrical certification (NICEIC or NAPIT), Gas Safe registration for gas work, and demonstrable fire-safety competence for HMO and fire-related projects.
