Replacing a Roof: How to Choose a Contractor for a Full Replacement

A full roof replacement is one of the few home purchases where the difference between a careful contractor and a careless one is measured in decades. The tiles look similar from the street; the batten spacing, the membrane, the ventilation and the fixings do not. This guide is about telling them apart before you sign.

Repair or replace?

The first honest question is whether you need a new roof at all. Repairs are usually the right answer when the problem is local: a slipped tile, a failed flashing around a chimney, a single leak after storms. Replacement starts to make sense when problems are systemic: widespread sagging, granules in the gutters, daylight through the felt, repeated leaks in different places, or a roof that has outlived its expected life.

Any contractor who quotes for a full replacement without going up to look at the roof, or at minimum inspecting it properly, is telling you something about how they work.

What a proper quote contains

A single figure is not a quote. Ask for a written document that covers:

• Scaffolding, including whether it is included, who arranges it and how long it stays up.
• Removal and disposal of the existing covering, plus the cost of a skip or licensed waste transfer.
• The specification: battens, membrane type, tiles or slates by name and manufacturer, ridge and hip products, fixings, and any lead work.
• Ventilation at eaves and ridge, which is routinely omitted and causes condensation problems years later.
• Roof windows or flues if they are being replaced or altered, and how the seals are formed.
• Gutters, fascias and soffits if included, and whether they are replaced or merely refitted.
• A workmanship guarantee, in writing, alongside any manufacturer material guarantee.
• The payment schedule, tied to stages of work rather than a large upfront sum.

If two quotes differ substantially, the difference is almost always in that list. Compare the specifications, not the totals.

Accreditations that are worth checking

Reputable roofers will hold at least one recognisable accreditation and be relaxed about you verifying it. Competent Roofer and NFRC membership both involve inspection of work rather than just a subscription. Manufacturer-approved installer schemes can extend material guarantees. Public liability insurance should be in place and evidenced.

Gas and electrical work connected with the job should be done by competent, registered people. And any contractor working at height should be able to explain their safety arrangements, including scaffolding rather than ladders where the work lasts more than a short period.

Red flags in roofing

Cold calling after a storm, offering to use materials "left over from a job nearby". A demand for cash and a large deposit on day one. Refusal to put the specification or guarantee in writing. A price that seems far below the others, usually achieved by skipping membrane, ventilation or waste removal. No fixed address, no reviews older than a few months, and a mobile number as the only contact.

Also treat with caution anyone who tells you your roof needs replacing based solely on a look from the pavement.

Timing, weather and expectations

Roofing is weather-dependent and honest contractors will say so. A full replacement typically takes a few days to a week for a straightforward domestic roof, and the roof should be left watertight at the end of each working day. Ask how they will handle that, particularly if rain is forecast mid-job.

Discuss timing of payment and what happens if the work stops for weather. And ask for the guarantee in writing with a name, address and date on it, because a guarantee on an undated invoice is a story rather than a contract.

Comparing roofers properly

Our roofing category lists local contractors with their reviews, insurance and verification status visible, so you can shortlist two or three and ask each for an itemised quote. For a purchase this size, spending a fortnight comparing is the cheapest insurance you will ever buy.