The short answer
A commercial roof needs edge protection or fall arrest whenever people have to work near an unprotected edge or a fragile surface, and that includes routine maintenance visits, not only the re-roof. Guardrails keep people from the edge, while lines and anchors catch a fall that has already started. The right choice depends on how often the roof is visited and how it is built, so it is best settled at survey.
Two different jobs: stopping a fall and catching one
This is part of our commercial roofing work. People often use the phrases as if they meant the same thing. They do not, and the difference decides what you buy.
Edge protection is a physical barrier. A guardrail around the perimeter, a parapet raised to a safe height, or a set of fixed handrails beside a roof hatch stops a person reaching the drop in the first place. Nobody needs training to be protected by it, and nobody has to clip onto anything.
Fall arrest works the other way round. It assumes a person could go over the edge and arranges for them to be stopped. A harness is clipped to an anchor point or a horizontal line, and a lanyard limits how far they drop. It needs trained users, inspected equipment and a plan for rescue. The Work at Height Regulations 2005 say planning includes emergencies and rescue, and a person left hanging in a harness has to be reached quickly.
There is also restraint, a short lanyard that physically cannot reach the edge. It sits between the two and suits roofs where only a few people ever go up. HSE's guidance on those regulations is to consider collective protection, which protects everyone at risk, before personal protection that relies on each person using it correctly. Your health and safety adviser or the person responsible for the building will know how that is expressed in your own risk assessment.
When the answer is yes
A permanent system makes sense when the roof is visited more than once or twice in its life. Think about who goes up and why.
- Gutter and outlet clearance. Box gutters and valley gutters on industrial units fill with leaves and debris and need regular clearing. Box gutters are troughs lined with lead or a membrane, carried between slopes or tucked behind a parapet, and it often runs close to an edge.
- Plant and equipment. Extract fans, air handling units and aerials need servicing, and the engineer visiting is rarely a roofer.
- Rooflights. Old rooflights are a hazard in their own right, because the plastic or wired glass can no longer carry a person. Our page on fragile roof safety covers how we deal with them.
- Inspection. Anyone checking the roof after a storm or at a lease break has to reach every part of it.
- Solar or other later additions. Panels create more reasons to be on the roof for years to come.
If the answer to all of these is that nobody ever goes up, a system may not be needed. In practice most commercial roofs are visited by somebody, and the question is whether they are protected when they are.
What a permanent system is made of
A handful of arrangements cover most buildings. Which one fits turns on the construction of the roof and the way the building is used.
On a flat roof with a parapet, the parapet itself may be too low to count as protection. For construction work, the regulations set the top guard-rail at no less than 950 millimetres. A freestanding guardrail on weighted bases can sit on the membrane without penetrating it, which suits a roof you do not want to drill. Where the deck can take fixings, posts are bolted through and the membrane is dressed around them with sealed collars.
On a profiled metal roof, a guardrail can be clamped to the standing seams or fixed through the sheets into the purlins, the horizontal beams that carry them. A line system is more common here: anchor posts at each end with a stainless steel cable between, and a harness runner that slides along the cable so the user never has to unclip.
Single anchor points suit small roofs with a hatch and a short walk to the plant. Whatever is chosen, the fixings must reach a part of the structure that can take the load. That means the rafters, purlins or deck, never the roof covering alone. We look at what is underneath at the survey, since a system fixed to tired timber or corroded steel is worse than none.
Why it belongs in a re-roof, not after it
Fixing a safety system to a finished roof means making new holes through a new covering. Every hole gives water a way in, so each one needs sealing with care. Done during the re-roof, the posts, bases and collars are built into the waterproofing from the start, with the layers lapped around them as they go down.
The same goes for the structure. When the old covering is off, we can see the condition of the deck and purlins and fix to sound material, replacing what is not. Access matters too. A new hatch, a fixed ladder or a safe route to plant can be added while the scaffold and the crew are already there.
It also affects the guarantee conversation. A system added later by someone else, with penetrations through a roof we have laid, can complicate any future leak investigation. If you expect to add one, say so at the start, so the detail can be drawn once and fitted properly. Your re-roof programme can include the fitting time.
Inspection, training and who is responsible
Equipment that is never inspected cannot be trusted. Lines, anchors and harness equipment are normally inspected on a regular cycle by a competent person, and the records are kept. If the last inspection date is unknown, treat the system as unchecked until someone confirms it.
HSE says the regulations apply to employers and to anyone who controls work at height, including facilities managers and building owners who bring in contractors. That might be the freeholder, the managing agent or the tenant under a full repairing lease. People often assume somebody else owns it. Check the lease and ask your insurer or health and safety adviser what they expect. Legal duties are for your own adviser to set out for your site.
Training matters as much as the hardware. Anyone clipping onto a line needs to know how to wear a harness, check the anchor and what to do if a colleague falls. A roof visit by an untrained contractor is a risk even with the best system in place.
A maintenance plan helps here. A roof maintenance contract gives each visit a purpose and a routine, and the safety system is checked as part of it.
Cost and how we handle it at survey
Cost depends on the length of edge, the type of roof, whether bases are weighted or fixed through, and how many people need access. Systems are priced on survey, and for the roof itself our page on commercial roof cost explains how a quote is built up. The price we fix in writing after the survey can list the safety system separately, so its share is clear.
On site we note how the roof is reached, where people will walk and where the plant sits. We photograph the edges, hatches and rooflights, and we note what is fixed to what. From that we can recommend a guardrail, a line or a mix, and explain why. Where a simpler option works, that is what we recommend, rather than specifying more than the roof needs.
Bring the details of who visits the roof and how often. That one fact changes the answer more than the size of the building does, and a short conversation up front saves a redesign later.
