Roofing guarantees: what they're actually worth

"Fully guaranteed for 25 years" is one of the most abused phrases in roofing. The words cost nothing to print; what matters is who stands behind them and what happens when things go wrong. Here is how the three layers actually work.

Layer 1: manufacturer material warranties

Tile, slate and membrane manufacturers warrant their products for long periods, sometimes decades. These numbers look impressive on a quote, but read the small print: they cover the product failing as a product, a manufacturing defect in the tile or membrane itself. They do not cover poor fitting, and most roof failures are fitting failures. A manufacturer warranty is worth having, and some require registration after installation, but it is the narrowest layer of the three. Long but narrow.

Layer 2: workmanship guarantees

This is the roofer's own promise to put right defects in their work, typically for 10 to 25 years. It covers the thing most likely to go wrong, but it has one structural weakness: it is only as good as the company's survival. If the firm stops trading, the guarantee dies with it, whatever number was written on it. Given how many small building firms fold within a decade, an unbacked 25-year guarantee is a hope, not a protection.

Layer 3: insurance-backed guarantees (IBGs)

An IBG is a policy from an independent insurer that honours the workmanship guarantee if the roofer ceases trading. It is the only layer that survives the company going bust, which makes it the gold standard for significant work such as a full roof replacement. Expect to receive an actual policy document or certificate from the insurer, not just a line on the quote. If the paperwork never arrives, the IBG does not exist.

What voids a roofing guarantee

• Unauthorised repairs: letting another contractor patch the roof usually voids cover on the whole area.
• Pressure washing: strips tile surfaces and forces water into the structure; many guarantees exclude it explicitly.
• Lack of maintenance: blocked gutters and outlets left uncleaned give insurers an easy out.
• Unapproved additions: solar panels, aerials or roof lights fixed through the covering without the guarantor's sign-off.
• Late reporting: sitting on a known leak for months can convert a covered defect into an excluded one.

Paperwork checklist before you sign

• Written workmanship guarantee: named property, scope of works, duration, conditions.
• IBG confirmed on the quote, with the insurer or scheme named.
• Manufacturer warranty terms, and who registers it after installation.
• The guarantee's maintenance conditions, so you know what you must do to keep it alive.
• Building regs completion certificate promised in writing.

Every one of these should be itemised on a professional quote. If they are not, ask why before money changes hands; our roofing quotes explained guide shows what a complete quote looks like. When the documents arrive, file them with your deeds. They are part of the value of your house.