No Snags

Before you contact anyone, get clear — even roughly — on what you're trying to achieve and what it involves. A vague ask ("do something about our heating") gets vague quotes back. A specific one ("replace the oil boiler with an air source heat pump, radiators upgraded where needed") gets you comparable, useful quotes.

• Ask what's actually possible now, not just what you're replacing like-for-like. A huge amount of work gets done as a straight swap — old boiler for new boiler, single glazing for the cheapest double glazing — simply because the homeowner never found out what else was on the table. Heat pumps, solar PV with battery storage, external wall insulation, EV chargers: most people only hear about these when a neighbour mentions it, not because anyone told them. Before you commit to "more of the same," ask a contractor or Home Energy Scotland what the alternatives actually cost and save over time — you may find the "upgrade" option is cheaper than you think once grants are factored in.
• Check if you need permission first. Extensions, some renewables installs, and anything touching a listed building or conservation area may need planning permission and/or a building warrant from your local council before work starts — not after. Your council's building standards team can tell you in a short phone call whether your specific job needs one.
• Check what funding exists — before you pick a contractor, not after. In Scotland, Home Energy Scotland (0808 808 2282) offers free, impartial advice and can point you toward grants and interest-free loans for heat pumps, insulation, and other energy work. This matters early because funding schemes usually require the installer to hold a specific accreditation (MCS for renewables, for example) — find out the rules first and it narrows your contractor search for you rather than causing a problem later.
• Write down your must-haves versus nice-to-haves. This becomes the backbone of your brief to contractors, and keeps quotes comparable later.

Word of mouth and completed local jobs you can actually go and look at are still the best source. Beyond that:

• Trade-specific registers are a faster shortcut than a general search: the MCS installer database for heat pumps, solar and other renewables; Gas Safe Register for anything gas; NICEIC or a similar body for electrical work. These aren't just directories — they're the same registers your funding body and your insurer will check against if you ever need to make a claim.
• Accreditation schemes like SafeContractor or Constructionline aren't legally required for domestic work, but a contractor who's bothered to get one has already had their health & safety, insurance and qualifications independently checked — worth asking about even if you don't recognise the badge.
• Get at least three quotes for anything substantial — and pay attention to the spread, not just the numbers. For a well-defined job, expect the highest quote to land somewhere around 20–30% above the lowest for broadly the same scope. If the spread is much wider than that, someone has either missed something (and will find it — and charge you for it — once the walls are open) or padded the price because they don't really want the job. Ask the outlier why.
• A company that's been trading five-plus years and still has the same phone number is telling you something — building work generates a lot of one-job, one-year companies that disappear the moment a defect shows up.

Before you commit to anyone, ask for — and actually look at — the following. A contractor worth hiring will have these ready without a fuss:

• Public liability insurance (and employer's liability if they have staff) — ask to see the certificate itself, and check the expiry date on it, not just be told it exists. A lapsed policy is worse than none, because it gives you false confidence.
• Relevant trade registration for the specific work — Gas Safe card, MCS certificate number, NICEIC number, whatever applies. Numbers can be checked directly against the register online in under a minute — do it, don't just take the card at face value.
• A couple of past customers you can actually contact, ideally with an address you could drive past — and ask them one question the contractor can't script for you: "did anything go wrong, and how did they deal with it?" A contractor with no history of anything ever going wrong is either very new or not being straight with you; how they handled a problem tells you far more than a spotless story.
• Their company details — a Companies House number if they're a limited company, not just a mobile number and a van. It costs nothing to look a limited company up on Companies House: how long it's existed, whether accounts are filed on time, and — worth specifically checking — whether the same director has a trail of previous dissolved companies behind them.
• Whether they'll be using subcontractors for any part of the job (an electrician, a plasterer, a specialist installer) — and if so, ask whether those subbies carry their own insurance too, or whether it all sits under the main contractor's cover.

A proper written quote — not a price scribbled on the back of an envelope — should set out:

• Exactly what's included, and just as importantly, what isn't (making good, waste removal, scaffolding, etc.)
• The materials and products being used, by name/spec where it matters
• A price, and whether it's fixed or could vary — and under what circumstances. If part of the job is genuinely unknown until walls or floors are opened up, that part should be a clearly marked provisional sum — an estimate flagged as such — rather than folded silently into the fixed price.
• A realistic start date and expected duration
• Payment terms — how much up front, how it's staged, when the final balance is due

On deposits: once a contract is signed, a deposit in the region of 20–30% to cover materials and secure a start date is normal for most domestic jobs. Anything approaching half the job value up front, especially in cash, is a real warning sign — a well-run business doesn't need your money to fund materials it hasn't ordered yet.

This deposit should arrive as a proper invoice, not a cash-in-hand request or a vague "just transfer me X" text — a legitimate contractor invoices for the deposit itself, for materials, and again for starting the works, the same way they'll invoice for every stage payment after. If you're just being asked to hand money over with nothing documenting what it's for, that's worth pausing on.

If a quote is vague on any of these, ask for it in writing before you compare it against anyone else's — a low headline price with a thin scope is not actually the cheaper option.

A written contract or signed acceptance of the quote protects both sides. It doesn't need to be complicated, but it should cover the scope, price, payment schedule, start/finish dates, and what happens if either side needs to change or end the arrangement. Verbal agreements are far harder to fall back on if something goes wrong later.

• Agree how "extras" get handled before you need one. Almost every job turns up at least one thing nobody could have priced up front — rotten timber behind a wall, a pipe run that isn't where the plans say. The contract should say that any extra cost gets agreed and priced with you before the work happens, not added to the final bill as a surprise.
• Know your cancellation rights. If you agreed the contract somewhere other than the contractor's own business premises — at your home, over the phone, online — you typically have a cooling-off period (commonly 14 days) to change your mind under UK consumer contract rules, even after signing. Ask if you're unsure, or check with Citizens Advice.
• Know where to go if it goes wrong. Before you need it, find out whether the contractor belongs to a dispute resolution or ombudsman scheme (many accreditation bodies include one). If they don't, your fallback is Trading Standards and, for genuinely serious disputes, the small claims process — worth knowing exists, rarely worth needing.

Once work is under way, a properly run job — regardless of trade — tends to share a few habits:

• Someone is clearly in charge on site, and you know who to call with a question.
• You're told about problems (a hidden pipe, an unexpected wall) as soon as they're found, with options and cost implications, not after the fact.
• The site is kept reasonably tidy day to day, not left as a hazard overnight — materials stacked safely, walkways clear, nothing left where a child or a pet could get into it.
• Any subcontractors on site (electricians, plumbers etc.) are clearly working to the main contractor's plan, not turning up unannounced. You should be able to ask "who's coming tomorrow and why" and get a straight answer.
• You're getting some form of regular update — even a short one — rather than radio silence between the start date and a surprise invoice.

You're entitled to ask for a quick walk-round at any point — a contractor confident in their own work will welcome it. If a contractor bristles at a reasonable request to look at work in progress, treat that as information.

Timelines vary hugely by scope, but as a rough steer for common domestic jobs once work actually starts on site (not counting time spent waiting on permissions or materials):

Those figures are "boots on site" time only — the part that surprises most people is everything before it. A heat pump often has a 4–8 week lead time between survey and install slot once ordered; a building warrant application can take several weeks to be approved before work can legally start at all. Ask your contractor for both numbers separately — time to start, and time on site — so your expectations match reality from day one.

Ask your contractor for a realistic estimate against your specific job rather than relying on general ranges like these — ground conditions, access, and the age of the property all move the number.

Before you make the final payment, you should have:

• Any legally required certificates — electrical installation certificates, Gas Safe certificates, MCS commissioning certificate for renewables, building warrant completion certificate where one was needed.
• Manufacturer warranties for any products installed, and instructions for anything you'll need to operate or maintain (a heat pump controller, for instance).
• An updated Energy Performance Certificate (EPC) if the work changes it — a new heating system or insulation upgrade should improve your rating, but only if it's actually recorded.
• A chance to walk round and flag anything that isn't finished to your satisfaction (snagging) before you release the final balance.

It's reasonable to hold back a small amount — often referred to as retention — until a snag list is cleared, rather than releasing 100% on the day the crew packs up. Agree that figure and the timescale for fixing snags as part of the contract in step 5, not as a negotiation on the last day.

Keep all of this together — you'll want it if you ever sell the property, claim on a warranty, or need proof of compliance for an accreditation or insurance purpose down the line. For anything that gets covered up during the job — pipework in a floor void, cabling in a wall — ask for dated photos before it's closed in. It costs the contractor nothing to take them, and it's the only record you'll ever have of what's actually behind your walls.