Every roofing website tells you to use an accredited contractor. Almost none tells you where to check, which is the part that does the work.
Check the register, not the logo
Membership is asserted far more often than it is held, and it lapses quietly. Every scheme that matters here publishes a searchable list, so check the claim against the register rather than against the van:
- Competent person registration: nfrccps.com/find-a-contractor.html
- NFRC membership: nfrc.co.uk/find-a-member.html
- TrustMark: trustmark.org.uk/homeowner/find-a-tradesperson
- The insurer behind an insurance certificate: register.fca.org.uk
Search by the exact company name on the quote, not the trading name on the van. The two differ more often than you would expect, and a firm that appears on a register under a different legal entity is worth a question before it is worth a contract.
The credentials are not interchangeable
Competent person registration and ordinary NFRC membership come from the same organisation and mean different things. Registration under the scheme lets the contractor self-certify that replacement roof covering complies with the Building Regulations. Membership of the federation is a vetting exercise: trading record and financial stability, inspection of live and past contracts, and evidence of public, employers' and third-party insurance, with re-vetting every three years.
TrustMark is different again. It is the Government Endorsed Quality Scheme, licensed by the Department for Business and Trade, and it vets through approved scheme providers. Registered businesses must provide a minimum two-year workmanship and product guarantee, and must carry financial protection covering prepayments, deposits, post-completion workmanship, rectification of defects or major damage, and non-compliance with Building Regulations.
One to discount entirely: the Chartered Institute of Plumbing and Heating Engineering has no roofing remit whatsoever. A roofer citing CIPHE membership as a roofing credential is either confused about their own trade body or hoping you will not look it up.
What an insurance-backed guarantee covers
What gets conflated here is worth separating out, because the separation is most of the value.
The contractor's own guarantee is a promise from the contractor. It is worth exactly as much as the contractor's continued existence, which is to say nothing at all if the firm ceases trading. As the NFRC puts it, even the best contractors can go out of business, whereupon their own guarantees become worthless.
An insurance-backed guarantee is independent cover that survives the contractor's insolvency. The NFRC recommends buying one, and is candid about the catch: there is an additional cost, and there also tends to be a high excess to consider. Ask what the excess is before treating an IBG as a solved problem.
Deposit and prepayment protection is a third thing again, covering money you have paid before work is done rather than defects afterwards. A guarantee, however long, does not protect a deposit.
On a Victorian roof, ask about salvage
Much of South London's housing stock is slated, and this is where a good roofer stands apart in a way you can hear in the conversation.
A 90-year-old roof can need stripping and relaying while most of its slates are still perfectly serviceable, because the underlay and the fixings give out long before the covering does. The component lifespans are in the answer on how many years a roof usually lasts.
A roofer who plans to strip carefully, sort the sound slates and relay them is cutting the largest material line on a slate quote. One who has priced an all-new order without mentioning the option may be quicker on site, but you should know which you are buying, because the two quotes will look nothing alike.
References worth asking for
Ask for addresses rather than testimonials, and ask for roofs of the same kind and the same age as yours: slate rather than concrete, Victorian rather than post-war. A roof three or four winters old tells you far more than one finished last month, because the failures that matter show up in weather rather than on handover day.
The whole of this takes one evening, and it is the only part of the process still entirely in your hands.