Solar Panels on an Asbestos Roof: Overclad, Replace or Go Elsewhere

Can solar go on an asbestos cement roof?

Sometimes, but rarely as it stands. Three things decide it:

• Disturbing the sheets. Fixing rails usually means drilling or clamping the sheets. HSE lists maintenance on asbestos cement roof sheeting as non-licensed work, but work that substantially breaks the sheets up is notifiable (HSE). Either way it needs a contractor trained for it.
• Fragility. HSE says all roofs should be treated as fragile until a competent person confirms they aren't, and lists non-reinforced fibre cement sheets among the materials likely to be fragile (HSE).
• Structure and remaining life. MCS requires the roof structure to be checked by a competent person, and a structural engineer where a roof is unusual, altered or shows signs of distress (MIS 3002). Panels last for decades; an old roof may not.

Overclad, replace or leave alone: the three options

Roofing contractors quote the roof; the solar installer quotes the panels. If you plan both, have them talk to each other early so the new roof is chosen and fixed with the panels in mind.

Your duties as the building's owner or occupier

The Control of Asbestos Regulations 2012 put a duty to manage asbestos on whoever is responsible for maintaining or repairing non-domestic premises (regulation 4). In short, they must:

• Assess. Make a suitable and sufficient assessment of whether asbestos is or may be present, and its condition.
• Presume. Treat material as asbestos unless there is strong evidence it isn't.
• Plan and record. Prepare a written plan for managing the risk, put it into practice and keep it under review.
• Tell people. Make information on its location and condition available to anyone liable to disturb it, which includes a solar installer.

HSE describes two kinds of survey (HSE): a management survey for everyday management, and a refurbishment or demolition survey, which must find asbestos, including that hidden in the structure, before any structural work. Ask your asbestos surveyor which the roof work needs.

What the solar survey checks on an asbestos roof

• Your asbestos register and survey. So the installer knows what the roof is made of and its condition before anyone goes up.
• Access without stepping on the roof. Working from below or from platforms, with staging, guard rails or nets where people must be near the sheets.
• The structure. Purlins, trusses or steelwork, and whether a structural engineer is needed for the extra load.
• The roof's remaining life. Whether it makes sense to overclad or replace before panels go on.
• Alternatives on site. Spare land, a car park, or another roof in better condition.

Using the work to fix the roof too

An ageing asbestos cement roof is often a problem in its own right: leaks, fragile sheets and an entry on the asbestos register that needs managing. Planning the roof and the solar together means scaffolding and access are paid for once, and the new roof can be specified for the panels' fixings. Ask both contractors for a programme that shows who does what, and in what order.

Other places for the panels

• A car park canopy. In England, Class OA of the permitted development order covers solar canopies over non-domestic car parks, up to 4 metres high and at least 10 metres from homes, after a prior approval application (GPDO Part 14). See solar carports.
• The ground. Spare land near the supply, for example on a farm.
• Another roof. A newer building on the same site may be the better place, with a cable to where the power is used.

For farm buildings see solar panels for farms; for industrial units, factories and warehouses.