Access, edge protection and roof safety

The roof surface is the first question, before anything else

Before anybody considers ladders or platforms, the question is what the roof is made of and whether it will hold a person. Fibre cement sheet, older GRP rooflight sheets, wired glass in a north light, thin metal deck spanning a long way between purlins and any liner panel with no support beneath it should all be treated as fragile until established otherwise.

Falls through fragile roof surfaces remain one of the largest causes of death in construction, and rooflights specifically are over-represented in that figure because they sit flush with the roof plane, they are often overpainted or dirty enough to look like sheeting, and they are exactly where a rooflight crew is working.

The practical rule we work to is that the age and material of the existing glazing is established at survey, in writing, and nothing is walked on that has not been established as capable of taking a person. Assumptions are made against the roof, not in its favour.

Why the hierarchy of control decides the method

The order in which options are considered is fixed by the Work at Height Regulations and it is not a matter of preference. Avoid working at height where reasonably practicable. Where it cannot be avoided, prevent a fall using an existing safe place of work or collective protection. Where a fall cannot be prevented, minimise the distance and consequences using collective means. Only after that come personal protective measures.

Applied to a rooflight job that hierarchy has real consequences. It is why a properly boarded and edge-protected scaffold beats a harness, why a mobile platform working from outside the roof beats walking the deck, and why the answer to a fragile roof is very rarely “we will be careful”.

Collective measures protect everybody on the roof including people who are not ours: a maintenance engineer, a surveyor, someone from the tenant who has come up to look. Personal measures protect only the person wearing them, and only if they are attached.

Edge protection on a flat commercial roof

On a flat or low-pitched roof with a parapet, the parapet is checked before it is relied on. A parapet has to be high enough to act as a barrier and structurally sound enough to stop somebody, and a 400mm upstand in poor brickwork is neither. Where the parapet does not do the job, temporary edge protection goes up.

Free-standing counterweighted guardrail systems are the usual answer on a membrane roof because they need no penetrations, but they load the roof and they need to be set back from the edge, which sometimes conflicts with where the units are going. Clamped systems fixed to a parapet or to a structural upstand are lighter but need something to clamp to.

Either way the protection has to run far enough past the work area that somebody stepping back is still behind it, and it has to be in place before the first unit is broken out rather than at the point it becomes obviously necessary.

Scaffold, tower or mobile platform

Three methods cover most commercial rooflight work, and the choice turns on the building rather than the price.

A fourth option exists on some buildings and is worth asking about: a mast climber or a hoist already on site for other work. Sharing access with another contractor is cheaper for everyone and needs agreeing in writing before it is assumed.

Where a mobile platform stops being the answer

Platforms are attractive because they arrive in the morning and leave in the evening, and they are frequently the wrong choice on a rooflight job for two reasons.

The first is that a rooflight installation involves moving material onto the roof and waste off it, repeatedly, for several days. A platform basket is a poor material handling route and the cycle time is punishing.

The second is ground. Outriggers concentrate very high point loads, and a machine set up over a basement lightwell, a service duct, a drainage run or soft made ground is a serious risk. On a city centre building the standing is often the constraint that removes the option entirely.

Permanent access already on the building

Many commercial buildings already have an access provision: an internal roof hatch with a fixed ladder, an external cat ladder, a walkway between plant, a horizontal lifeline system. These are worth using when they are adequate and worth checking before they are trusted.

A roof hatch that opens onto a deck with no protection around it protects the climb and nothing after it. A cat ladder with no hoop guard, corroded fixings or a landing that has been removed is not an access route. And a walkway that runs to the plant deck but not to the rooflight bays only solves part of the problem.

Where the provision is adequate, the job gets cheaper and quieter and the building keeps a useful asset. Where it is not, the temporary arrangement stands in its place for the duration.

Existing fall-arrest systems, and whether they can be relied on

A horizontal lifeline or a set of anchor eyes on a commercial roof needs current inspection records before anybody clips to it. These systems require periodic examination, and the certificate is issued for the installation as a whole, not for the eye somebody points at.

Two things go wrong regularly. The records have lapsed, sometimes by years, because the building changed hands or the facilities contract changed. Or the system was designed for a different task: a line installed for gutter maintenance at the eaves does not necessarily provide restraint over a rooflight bay in the middle of the roof.

Where a system is in date and demonstrably suits the work, it is used. Where it is not, we do not clip to it and hope, and we do not certify it either. That inspection belongs to whoever owns the building.

The open hole is the hazard once the unit is out

The moment an old rooflight is removed there is a hole in the roof, and it is a hazard in both directions: somebody can fall through it and material can fall out of it. This is the part of the day that needs the most discipline, because it is also the busiest.

The working method is that the opening is never left unattended without a physical cover or a barrier around it. Covers are fixed down and marked, not laid on. Barriers are rigid, not tape. And the sequence is arranged so that the number of open holes at any moment is one, or as close to one as the job allows.

At the end of every working day the roof is closed. That is a fixed rule on our jobs and it is as much a safety rule as a weather one: an unattended opening on an unattended roof overnight is not something we leave behind.

Exclusion zones, and the space beneath the work

Everything above an occupied space needs a defined zone below it. On a warehouse that usually means racking aisles taken out of use and a floor area barriered off. On an office it means a room closed. On a retail frontage it means part of the shop floor fenced and, sometimes, the pavement outside licensed and hoarded.

The zone has to account for what could actually fall and how far it could travel, which is not the same as the footprint of the opening. Debris netting, a crash deck or a fully boarded scaffold lift beneath the work reduces the zone considerably and is often cheaper than losing floor area for a week. Our page on protecting a working space below goes into the containment side in more detail.

Wind, rain and the thresholds that stop work

Rooflight units are large, flat and light, which makes them sails. There is a wind speed above which a unit cannot be safely handled on a roof or lifted by a machine, and it is lower than people expect. Around 17 to 23 metres per second is where most platform manufacturers stop, and manual handling of a large glazed unit on an exposed roof becomes unwise well before that.

Rain matters for a different reason. A wet membrane, a wet metal deck and a frosted deck are all dramatically more slippery than they look, and a fall on a roof does not have to be a fall from a roof to be serious.

We build weather into the programme rather than pretending it away, which means a job priced with contingency for lost days rather than a job that quietly runs over. That sits alongside the phasing decisions covered in programme and phasing on a commercial roof.

Loading materials onto a roof

A large glazed unit can weigh well over 100kg and arrives in a crate that weighs more. How it gets to its position is a design decision, not something to work out on the morning.

The options are a hoist on a scaffold, a telehandler or crane lift, a goods lift inside the building where one exists and the unit will fit, or a manual carry where the unit is small enough and the route allows it. A crane lift brings its own requirements: a lift plan, an exclusion zone, an appointed person, road closure if the machine stands on the highway.

Where the material sits once it is up matters as well. A pallet of units point-loaded onto a lightweight deck between purlins is a genuine structural risk, and staging is spread across the structure rather than left where the hoist put it.

Rescue, and the question people forget to ask

Anywhere personal fall protection is in use, there has to be a plan for retrieving somebody who has fallen and is suspended, and it cannot be “call the fire service and wait”. Suspension in a harness becomes dangerous in minutes.

The plan is specific: who does what, what equipment is on site to do it, how the casualty is reached, and how long it will take. Writing it down is what forces the honest answer, and on a job where the honest answer is poor, the method changes to one where a fall cannot happen in the first place. That is the hierarchy doing its work.

Duties on a commercial site, and who holds them

Commercial roof work sits under the Construction (Design and Management) Regulations, and the duties are shared. The client has duties around making suitable arrangements, providing pre-construction information and allowing adequate time. Designers have duties around eliminating foreseeable risk. Contractors have duties around planning, managing and monitoring the work.

The pre-construction information is the piece that most affects a rooflight quotation, because it is where the building’s known hazards live: asbestos survey findings, fragile roof areas, live services in the ceiling void, restricted areas, the condition of any existing access system. Where it is provided, pricing is accurate. Where it is withheld or does not exist, everything after it is an assumption.

Asbestos, and why it stops a job dead

On any commercial building built or altered before 2000, asbestos has to be considered before a roof is disturbed. Cement roof sheets, rooflight sheeting compounds, bituminous flashings, gaskets and mastics around older frames, and insulation board in ceiling voids are all realistic locations.

The duty holder for the building is required to hold an asbestos management survey and to make it available to anybody who might disturb the fabric. If we ask for it and it does not exist, the work does not start. That is not caution for its own sake: breaking out an old rooflight kerb bedded in an asbestos-containing compound turns a routine day into a notifiable incident.

What access costs, and why it is a separate line

Access is quoted separately from the installation because it varies far more than the installation does. Two identical rooflights, one on a single-storey flat roof with an internal hatch and one on a 9m warehouse eaves with a fragile deck and no standing for a machine, are the same day’s fitting and a completely different job.

Separating the lines lets a client see where the money is going and, more usefully, lets them change it. Coordinating with another contractor’s scaffold, moving the work to a week when the yard is clear, or opening a shutter to allow a telehandler in are all decisions that reduce the access line, and none of them are visible if the price arrives as one number.

What we need to price access properly

Send us the roof construction and its approximate age, the eaves height, what the existing rooflights are made of if any are being replaced, and photographs of the ground conditions on every side of the building. Any asbestos survey, any inspection records for an existing fall protection system, and any restriction on vehicle access or working hours.

With that we can give a range by email and a fixed price after a survey, and the survey is where the access method is settled rather than guessed. Call 01865 704245 or email info@heritageskylightsoxford.co.uk. Where a building’s roof needs remedial work by a roofing contractor before new glazing is worth fitting, we will tell you that instead of quoting.