Replace industrial rooflights when they pass their service age for the material, or sooner if condition triggers appear: yellowing and lost daylight, a brittle or bloomed surface, repeat leaks, or a failed fragility assessment. As a planning rule, GRP over about twenty years old should be treated as fragile and programmed for replacement whatever it looks like, because non-fragility degrades invisibly with age. Age and repeat leaks are the two strongest signals.
This answer sits under our commercial skylight installation service and gives a duty-holder checklist. It is not a substitute for a competent fragility assessment of your actual roof.
Age bands by material
| Material | Indicative service age | Treat as fragile from |
|---|---|---|
| GRP, basic gelcoat | 10 to 15 years | About 15 years |
| GRP, polyester surfacing film | 15 to 25 years | About 20 years |
| GRP, high performance film | 25 years plus | By condition and assessment |
| Multiwall polycarbonate | 20 to 30 years | By condition and assessment |
| Glass sealed units | 25 years plus | By seal failure and framing condition |
Coastal and port-side sheets sit at the shorter end of each band. Age is a planning trigger, not a certificate of safety: a sheet within its band can still be fragile, and one is assumed fragile once undated or over the fragility age.
The condition triggers
Age sets the programme, but condition can bring replacement forward. Any of these is a reason to survey and prioritise a rooflight now.
- Yellowing and lost daylight. Sheets noticeably darker than when installed, with the lights coming on earlier, mean the transmission has fallen and the resin is degrading.
- Fibre bloom and a rough surface. A surface that has gone from smooth to fibrous is past the point where the protective film is doing its job, and the laminate is exposed.
- Brittleness. A sheet that feels brittle, or that has cracked around fixings or at the laps, has embrittled, and embrittlement is the loss of the property that arrests a fall.
- Repeat leaks. More than one round of sealant on the same rooflight or lap means the components there have failed and no further sealant will hold. Our warehouse rooflight leak replacement page covers this.
- A failed or absent fragility assessment. No current non-fragility record for the assembly, or a failed assessment, means the rooflight is fragile for planning purposes.
A duty-holder checklist. Do you know the age of your rooflights? Do you hold a non-fragility record for the configuration installed? Are any yellowed, bloomed, brittle or leaking repeatedly? Are any over walking routes, access points or plant? If you cannot answer the first two, or answer yes to the rest, the rooflights should be surveyed and treated as fragile until assessed. Never test a suspect rooflight by standing on or near it.
Why age matters as much as appearance
The reason age carries so much weight is that the most dangerous failure, embrittlement, is invisible. A rooflight can look serviceable and no longer hold a person, because ultraviolet degradation of the resin removes the load-arresting strength before it shows on the surface. So a rooflight is not judged safe by looking sound from the floor. Non-fragility is a tested assembly classification that degrades with age, and once a GRP rooflight is past about twenty years it is assumed fragile regardless of appearance. Our what non-fragile means answer covers this.
What it means around Ipswich
The industrial stock across Ipswich, the port estates and the Suffolk and north Essex estates was largely built between the 1970s and early 2000s, so a great many roofs are now thirty years old on rooflights specified for fifteen to twenty. In practice most of this stock is past its service age and running on rooflights that should be treated as fragile. On the coastal belt near Felixstowe the shorter service life brings that forward. This is why a phased survey and replacement programme is the common conversation on these estates.
How old is too old for an industrial rooflight?
As a planning rule, GRP over about twenty years should be treated as fragile and programmed for replacement whatever it looks like, because non-fragility degrades invisibly with age. Basic gelcoat sheets reach that point around fifteen years. Polycarbonate and glass last longer and are judged more by condition. Coastal sheets sit at the shorter end of every band.
My rooflights look fine. Do they still need replacing?
Possibly, because the most dangerous failure is invisible. A rooflight can look sound and keep the rain out while having embrittled to the point where it will not arrest a fall. Age and provenance matter more than appearance. If they are over their fragility age or you hold no non-fragility record, they should be surveyed and treated as fragile until assessed.
Find out where your rooflights stand
A survey grades every rooflight on age and condition and gives you a programme timed by risk. That replaces guesswork with a defensible position.
Request a survey. Read across to replacing rooflights during a roof refurbishment, what to do about a fall-through risk, and the phased programme guide.
Thinking about this job? We survey across Ipswich, Suffolk and north Essex and give you a fixed price before any work starts, with a 10-year workmanship guarantee.