A roofing quote is mostly a scope document with a number at the bottom, and the number is the part you can read. These questions expose the rest of it, which is where quotes for the same house end up thousands apart.
Are you registered with a roofing competent person scheme?
Schedule 3 of the Building Regulations 2010, paragraph 16, authorises two schemes to self-certify replacement of a pitched or flat roof covering: the National Federation of Roofing Contractors and NAPIT. Most consumer content mentions only the first. Solar panel installation is expressly excluded from both.
A registered contractor certifies that the work complies with the Building Regulations without a Building Control inspection, notifies your council, and you receive a Building Regulation Compliance Certificate. If the roofer is not registered, the work still needs approval. It has to come through local authority building control or a registered building control approver instead, and someone has to arrange and pay for it. Establish which route the quote assumes. As gov.uk puts it, without approval you will not have the certificates of compliance you may need when you sell.
What insurance do you carry, and do you employ anyone?
The legal position is useful here, because the two main covers sit on opposite sides of it.
Employers' liability insurance is compulsory under the Employers' Liability (Compulsory Insurance) Act 1969 for any firm with employees, with a statutory minimum of £5 million, though HSE notes most insurers offer at least £10 million. A sole trader with no staff is outside the Act. A limited company employing only its owner is exempt only where that person owns at least 50% of the issued share capital, and family businesses lose the exemption entirely once incorporated. HSE also warns that job titles do not settle it: what matters is the real nature of the relationship, so a roofer using regular "self-employed" labourers who work only for that firm, with that firm's equipment, may well need cover.
Public liability insurance is different. HSE describes it as generally voluntary, and a roofer without it is not breaking any law. For roofing, which means work at height over footways with materials that can fall, £2 million is a practical floor and £5 million is common. It is also worth asking whether the policy covers the height involved and any hot works such as torch-on felt, because restrictions of that kind exist in the market.
Is scaffolding in the quote, and who contracts it?
Scaffolding is often a separate line, and sometimes invoiced by a third party rather than the roofer. Ask who holds the contract with the scaffolder, because it determines who you chase if the scaffold arrives late, sits idle or damages a wall. Ask too whether you will be given the handover certificate and the seven-day inspection records that scaffolds legally require.
Is the pavement licence in the figure?
Scaffolding over a public footway needs a licence from the borough, typically £150 to £600 in inner London. This is a council fee rather than a trade rate, and it is one of the commonest items to be left out of a quote and added later.
Is that price inclusive or exclusive of VAT?
Published cost guides headline figures that exclude VAT, and quotes vary in practice. Twenty per cent on a £10,000 re-roof is £2,000, which is more than the gap you are probably trying to judge between firms. If one roofer quotes no VAT at all, the innocent explanation usually applies: the registration threshold is £90,000 of taxable turnover, so a small sole trader legitimately charges none.
What is the payment schedule?
Ask for staged payments tied to completed, verifiable stages, with the final payment falling due on completion after snagging. Where a deposit is requested, ask what it buys. Both the FMB and TrustMark frame the legitimate upfront payment as a contribution towards materials rather than a payment for labour not yet done.
What happens if the battens or felt are worse than expected?
On a Victorian roof this is not a hypothetical. The covering routinely outlives what sits beneath it, and rotten batten ends or perished underlay only appear once the slates are off. A quote carrying no provisional sum for timber is incomplete rather than cheap, so ask what the rate would be and who decides the work is needed.
Ask also what happens to the specification. Under section 11 of the Consumer Rights Act 2015, pre-contract information about the main characteristics of goods becomes a term of the contract, and a change is not effective unless expressly agreed. The membrane and tiles named in your quote are what you have contracted for, and a cheaper substitute is not something the roofer can decide alone.
Ask the same questions of everyone you shortlist.