Question answered
How long does a commercial roof last?
The short answer
It depends on the system. Published UK guides put flat roofs generally at 15 to 30 years, torch-on felt at 10 to 20, EPDM at 20 to 30 years or more and GRP at 25 to 40, while zinc is quoted at 100 years or more. Drainage, workmanship and upkeep move every figure up or down, and none of them is a promise.
A commercial roof can last anywhere from about a decade to more than a century, depending on the system, the workmanship and the upkeep. These are the published ranges for each type.
Typical ranges for the common flat systems
Many shops, offices and units have a flat or low-pitched roof, so the covering on top largely decides the answer. MyBuilder's flat roof guide, updated 21 August 2026, reckons a flat roof will typically serve for between 15 and 30 years. Two terms first: EPDM is rubber sheeting laid in one piece, and GRP is a fibreglass laminate set in resin. Treat the table as a picture of the spread, not a forecast for your building, because the published guides do not always agree with each other.
| System | Typical life | Published by |
|---|---|---|
| Torch-on felt | 10 to 20 years | Less, March 2026 |
| EPDM single-ply | 20 to 30 years or more | GreenSpec (Less says 30 to 50) |
| GRP | 25 to 40 years | Less, March 2026 |
| Lead sheet | 50 to 100 years | Less, March 2026 |
Felt shows the spread best. Less puts good felt work at about 20 years and says poorly laid felt can give up in under 10, so the care taken over laps and details counts for as much as the material itself.
Zinc, lead and profiled metal sheet
Metal sits at the long end of the scale. One zinc manufacturer's FAQ says a zinc roof can outlast 100 years and points to a Building Research Establishment environmental declaration that states 100 years, while HomeBuilding, quoting a contractor, gives 60 to 100. Lead on a flat roof is put at 50 to 100 years in the table above, which makes both metals a long-term choice where the structure can carry their weight and the budget allows. The trade-off is cost at the outset and the need for skilled installation, since a long-lived metal laid badly still fails early at its joints.
Most industrial units are different again. They carry profiled steel sheeting, the ribbed or trapezoidal panels you see on warehouses, and one number for it would mislead. How long it lasts turns on the coating, the fixings and the raw edges left where a sheet was cut to fit. That is why an older metal roof gets its edges checked early, and why cut edge corrosion has a page of its own.
What shortens a roof's life
Water that stays put is the usual enemy. IKO, citing the 2018 edition of BS 6229 (since revised), recommends a finished minimum fall of 1:80 on a flat roof and designing for 1:40 to leave room for build tolerances and structural deflection. A roof laid flatter than that holds ponds, and a pond works on the covering, the laps and the fixings every single day. Blocked outlets produce the same effect, which is why commercial roof drainage deserves attention long before a stain appears on a ceiling.
Other causes are plainer. Engineers who walk the same route to a rooftop unit wear a path through the covering, and a walkway or protective boards stops that. Poor detailing at upstands, pipes and rooflight edges lets water in at small points. A small repair put off for another year tends to become a larger one. Regular checks catch most of this before the repair grows into a replacement.
What a warranty does and does not tell you
A manufacturer's warranty states what the maker will cover, for how long and under what conditions. It deals with defined faults and does not predict the roof's working life. When you compare systems, ask what the warranty covers, who has to carry out the installation, what upkeep it demands and whether a buyer or incoming tenant inherits it. Then read the conditions properly, because a missed inspection or an unapproved repair can matter.
The same questions apply to any contractor's guarantee on a commercial job. Ask for it in writing, establish what it covers and for how many years, and file it with the building's other records so that whoever next looks after the roof can find it without a search. A guarantee you cannot locate in year eight is worth very little.
Repair, overlay or replace as the roof ages
As a roof nears the end of its published range, the question changes from how long it has left to what it needs now. A repair suits a roof whose covering is still sound and whose fault is local. A new membrane over the old one can work on a roof with dry insulation and a dry deck. Full replacement becomes the answer once the deck is wet or the covering has failed across a wide area, because patching beyond that point only delays the bill. Our commercial roofing service covers all three.
The visit comes first, with pictures of the actual roof and a quote in writing that gives a single total. Area, access, the system chosen and what lies underneath move the price; the commercial roof cost guide sets out the published ranges, and VAT is added at the standard rate. Replacing like for like usually avoids planning permission, but planning for commercial roof work explains the exceptions.
Roof age: two more questions
My flat felt roof is 12 years old: is it due for replacement?
Not necessarily. Less puts torch-on felt at 10 to 20 years, with a well-laid roof reaching 20 and a badly laid one failing in under 10. Age alone does not decide it. Blistering, open laps, ponding and repeated leaks do, and a survey shows which end of the range your roof sits at.
Do metal roofs near the sea wear out faster?
A zinc manufacturer reports very good results for the metal near the sea, though salt air can leave white deposits on surfaces that rain never rinses, and it suggests a twice-yearly wash with clean water to limit them. Steel sheeting is a different case: the coating and the cut edges are the first things to check on a coastal unit.
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10-year workmanship guarantee, in writing.