How we pick the companies on each list

Is this job the company’s main trade?

First, the work each company actually does. Companies whose everyday work matches the list come ahead of those that take such jobs on now and then, among many other things. We leave out builders’ merchants, DIY stores, manufacturers that only supply the trade and skip hire firms, along with sites that simply pass enquiries to other firms.

The resin driveway pages are for installers that lay resin-bound or resin-bonded surfaces as a steady part of what they do, not paving firms that mention resin once. Inside a list, the composite door, bifold door and sash window buttons show the double glazing companies that say they fit them, the orangery button shows conservatory builders that build orangeries, and the flat roof and fascia buttons show roofers that take on that work.

What homeowners have said, over time

Then there is the reputation each company has built with its customers, in comments anyone can look up and weigh for themselves. That record is set against the years the company has been trading, so a long, steady history counts for more than a burst of praise in a firm’s first months. On jobs that last weeks, such as an extension or a loft conversion, remarks about how the site was run and how problems were put right often say more than remarks about the finish.

What the company shows before you call

We then go through what each company says about its own work, on its website and on its social and trade profiles. Are there photos of finished jobs, ideally before and after? Does it say which areas it covers, whether its own fitters do the work or subcontractors, and which schemes it belongs to, such as FENSA, Certass, TrustMark, Gas Safe or CompetentRoofer? Is it clear about its guarantees, whether the deposit and the workmanship guarantee are insurance-backed, and how payments are staged? A company that sets all this out openly is far easier to compare.

Independence

Each list’s order is our own editorial choice, based on merit, and each list is revisited at intervals. Getting in costs a company nothing, and money cannot buy a change in the criteria. A company already on a list may take Pro, which puts contact buttons, project photos, its areas, schemes, guarantees and payment options on its page, or Top, which gives it one of the first three spots. Both plans always carry a label. Appearing on a list does not mean we endorse a company.

Checks worth making before you hire

Windows and doors. In England and Wales, replacement windows and external doors must meet Building Regulations. An installer registered with FENSA, Certass or another competent person scheme can certify the work itself, and you should receive a certificate afterwards. Both schemes list their registered installers online. If the installer is not registered, the work needs approval from Building Control.

Extensions and loft conversions. Both need Building Regulations approval, and at the end Building Control, at the council or a private approver, issues a completion certificate. Keep it, because a buyer’s solicitor will ask for it when you sell. Some projects also need planning permission while others come under permitted development, which the Planning Portal or the council can help you confirm. Work on a shared wall in England and Wales usually means serving a party wall notice on the neighbours.

Gas and electrics. Anyone working on gas, such as moving a hob or a boiler, must be on the Gas Safe Register. The engineer’s ID card shows the work they are qualified for, and the number can be checked on the register’s website. Electrical work in a new kitchen or bathroom should be done by an electrician registered with NICEIC, NAPIT or a similar scheme, who can certify it under Building Regulations. Both have an online search.

TrustMark and guarantees. TrustMark is the government endorsed quality scheme for work in and around the home, and its online register shows which firms are currently registered. Whatever the trade, ask for proof of public liability insurance, a written quote and contract, and whether your deposit and the workmanship guarantee are insurance-backed, so they still hold if the company stops trading.

Scotland and Northern Ireland. In Scotland, most building work needs a building warrant from the council before it starts. Northern Ireland has its own Building Regulations, handled by the building control teams of the district councils. If a detail on our pages has changed, let us know at the address on the contact page.