The short answer
A fragile roof is one that will not safely carry a person's weight, or anything they might be carrying. Fibre cement sheets, old rooflights, corroded metal sheets, liner panels, glass and rotten boards are the usual examples, and HSE says every roof should be treated as fragile until a competent person confirms otherwise. The Work at Height Regulations 2005 require work to avoid fragile surfaces where possible, protect them where not, and mark them with warning notices.
On this page
Every year people fall through roofs while doing something that seemed minor: clearing a gutter, looking for a leak, fixing a satellite dish. HSE says falls through fragile surfaces, particularly fibre cement roofs and rooflights, account for 22% of all fatal falls from height in construction. Many of those roofs belong to ordinary businesses, and the person who fell was often not a roofer. If you are responsible for a building, this is the note to read before anyone goes up.
What counts as fragile
A surface is fragile if it would not safely support a person, and anything they are carrying, if they stepped or fell onto it. HSE lists these as likely to be fragile:
| Material | Why it is fragile |
|---|---|
| Fibre cement sheets | Non-reinforced sheets break under a person’s weight, whatever their profile, and become more brittle with age |
| Rooflights | Especially those in the plane of the roof, which can be hard to see in some light or when painted or dirty |
| Liner panels | The inner skin of built-up sheet roofs, never designed to be walked on |
| Corroded metal sheets | Rust thins the steel until it gives way |
| Glass, including wired glass | Breaks under impact |
| Rotted chipboard and similar | Flat roof decks that have been wet for years |
| Wood wool slabs, slates and tiles | Not designed to take a point load |
The rule of thumb in HSE guidance is simple: treat every roof as fragile until a competent person has confirmed that it is not. A roof that looks solid may have a rooflight under a layer of moss, or sheets that have been thinning for twenty years.
What the law expects
Regulation 9 of the Work at Height Regulations 2005 deals directly with fragile surfaces. In summary, it requires anyone controlling work at height to:
- Avoid people working on, passing across or working near a fragile surface where the work can reasonably be done safely without that.
- Protect where that is not possible: suitable platforms, coverings, guard rails or similar, able to take any foreseeable load, and measures to reduce the distance and consequences of any fall that remains possible.
- Warn, with prominent notices at the approach to a fragile surface, or by other means where notices are not practicable.
HSE’s roof work guidance adds that rooflights must be protected by secured barriers or covers labelled with a warning, and that precautions must be in place however short the job. A two-minute look at a leak is covered.
Under the Construction (Design and Management) Regulations 2015, a business commissioning roof work is a client, with duties to make sure the work is properly planned and to pass on information it holds, including where the fragile surfaces are.
What this means for a building owner
Mark the roof
Fit warning signs at every access point to a fragile roof, such as ladders, hatches and adjacent flat roofs. Many older industrial units have no signs at all.
Control access
Lock roof hatches and fixed ladders. Make it a rule that nobody goes onto the roof without a plan, including your own maintenance staff and contractors visiting for something else, such as an air conditioning engineer.
Keep a roof plan
A simple drawing showing roof types, rooflights, fragile areas and safe routes, given to every contractor before they arrive. This is the kind of information CDM expects a client to share.
Choose contractors who plan for it
A competent roofing contractor will describe how they will avoid or protect fragile surfaces: working from a platform or staging, netting below, edge protection, rooflight covers, or a mobile elevating work platform so nobody stands on the roof at all. Ask for this in the method statement.
Use drones for looking
Most “just have a look” trips onto a roof can now be replaced with a drone survey, which photographs the whole roof without anybody on it.
Fibre cement and asbestos
Many fragile roofs are fibre cement sheets from before 2000, which may contain asbestos. That adds a second set of rules. Removing undamaged asbestos cement sheets carefully, without breaking them up, is usually non-licensed work under HSE guidance; work where the sheets will be substantially damaged or broken becomes notifiable non-licensed work, with extra duties. Either way, it needs a risk assessment, trained operatives and proper disposal. Overcladding, where a new roof is built over the old sheets, avoids removing them and is common on older industrial units. See roof overcladding.
Making a fragile roof safer for good
Some changes reduce the risk permanently:
- Replace old rooflights with non-fragile rated rooflights when the roof is refurbished.
- Fit rooflight guards or mesh below or over existing rooflights.
- Install walkways and guardrails along routes that maintenance staff must use, such as to plant or gutters.
- Overclad or replace fibre cement roofs at the end of their life, rather than repairing them sheet by sheet.
A roof survey is a good moment to record all of this, and many survey reports include a fragility assessment and access recommendations alongside the condition grades.
The short version
If a roof has rooflights, fibre cement sheets or old metal sheets, treat it as fragile. Nobody goes up without a plan. Contractors should show how they will keep people off fragile surfaces or protect them, and the warning signs should be on every route up.
If your roof needs work and nobody should be standing on it, the form below gets it priced by a contractor who will plan around the fragile areas. See Commercial Roofing UK for the routes from repair to overcladding.