Manufacturer warranties on commercial roofs

1A warranty covers faults, not the roof's whole life

A warranty is a contract. It says what the manufacturer will do if a named defect appears within a set period, and it says what the owner must do to keep that cover alive. The number on the front is the length of the promise. It tells you nothing certain about the day the roof will wear out.

Marley makes the point about its own concrete tiles. It describes them as expected to last for around 60 years, then takes care to say that figure is neither a guarantee nor a warranty. Expected life and written cover are two different documents, even from one manufacturer, and a buyer of any commercial roof should read them as such.

For a commercial owner the distinction matters at budget time. A twenty year warranty on a membrane does not mean twenty years without spending on that roof. Gutters, outlets, flashings and penetrations all need attention inside the period, and a small neglected fault can be the reason a claim is later refused.

2What published lifespans say, and where they disagree

MyBuilder's flat roof guide, updated 21 August 2026, puts a flat roof at 15 to 30 years in general. The system underneath moves that figure, and published numbers differ from one guide to the next, as the rows below show. The spread is wide enough that a single warranty term cannot stand in for it.

Less notes that a well-laid felt roof can reach 20 years whereas a badly laid one may go within 10. Workmanship alone can double the outcome, and no warranty length captures that. Our page on how long a commercial roof lasts covers each system in more detail.

3Conditions that tend to sit behind the headline

Read the conditions before the headline. Warranties commonly depend on the roof being installed to the manufacturer's method, by someone the manufacturer accepts, and then maintained. Some tie cover to regular inspections, some to keeping drainage clear, and some to controlling who goes on the roof afterwards. The exact wording varies by manufacturer and by product, so the only reliable source is the document itself.

Two everyday habits can quietly put cover at risk. One is letting outlets and gutters clog, which leaves water standing on the surface; see blocked outlets on a commercial roof. The other is fixing new items through the covering without telling the manufacturer, for example a bird-proofing scheme, as discussed in bird proofing a commercial roof.

Keep dated records of inspections, clearances and repairs. If a claim ever has to be made, a clear history is far easier to present than a recollection, and it shows the owner kept up their side of the bargain.

4Metal roofs, coatings and cut edges

Profiled metal sheeting brings a different question. The coating on the sheet is only part of the story. Where a sheet has been cut on site, the bare edge exposes the steel, and corrosion can start there. Our page on cut edge corrosion explains the process and what a survey looks for.

When a coating warranty is offered, ask whether it covers corrosion that begins at a cut edge, at a fixing or at an overlap, and whether site-cut edges are treated in a way the manufacturer accepts. A warranty may cover the factory finish and say nothing about what happens to a trimmed edge.

The same caution applies to older roofs that are being repaired rather than replaced. Patching an out-of-warranty roof with a different product can leave you with two systems, two sets of terms and no clear party to ask when it leaks again. A repair that is compatible with the existing covering is worth more than a cheap overlay of something else, so say which product is already there.

Fixings count here as well. Every screw into a metal sheet is a possible start for rust, which is one more reason to ask what the maker expects around penetrations and plant.

5Questions to ask before relying on any warranty

Ask for the document before the contract is signed, not after the work. Then put a handful of plain questions to the installer and the manufacturer. Who stands behind the promise if the installer stops trading? Is the cover insured, or is it a promise from the company alone? Can it pass to a new owner if the building is sold, and does that need notifying?

Ask what is excluded and how a claim is made. Find out whether the manufacturer must inspect before any repair, how long it has to respond, and whether work by a third party ends the cover. Ask too what you must do each year, so the obligations land in a maintenance diary rather than a drawer.

Finally, treat the warranty as one input to a decision. A well-built roof with good drainage and a recorded service history is the better protection, and survey photographs give you the first entry in that record. More on how we approach commercial roofing is on the hub page.