Asbestos Roofs and Solar Panels: What UK Warehouse Owners Must Know

Asbestos cement was used extensively in UK industrial construction from the 1950s through to the late 1990s. Asbestos cement profiled sheets, sometimes called "big six" or "super six" sheets, are the most common form found on warehouse roofs. They are typically grey-white in colour, corrugated or profiled, and have a characteristically rough, slightly granular texture.

Asbestos cement typically contains 10–15% chrysotile (white asbestos) by weight, bonded within a cement matrix. In intact, undamaged, and unweathered condition, asbestos cement is considered a lower-risk material because the fibres are bound within the cement and are not readily released into the air.

However, weathered, crumbling, or damaged asbestos cement is a different matter. Weathering over decades causes the cement binder to erode, exposing surface fibres that can become friable and potentially airborne. Before any solar survey or installation work, a Refurbishment and Demolition (R&D) asbestos survey must be conducted by a licensed surveyor under Regulation 4 of the Control of Asbestos Regulations 2012.

If your warehouse was built before 2000, assume asbestos may be present until a survey confirms otherwise. Do not attempt to collect samples yourself — this is licensed work. The survey will identify material type, condition, and risk rating, providing the information needed to determine whether solar installation is feasible.

Under the Control of Asbestos Regulations 2012, the duty holder (in most cases the building owner) has a duty to manage asbestos in the premises. This duty includes: maintaining an up-to-date asbestos register for the building; ensuring all workers and contractors have access to the register before carrying out any work; and ensuring that work near asbestos is assessed for risk.

Before a solar installer can work on or near your asbestos roof, you must provide them with your asbestos register and any survey reports. Reputable commercial solar installers will require this documentation before proceeding. Any installer who does not request asbestos information before working on an older warehouse roof is operating outside legal requirements.

Work that does not disturb asbestos cement (such as installation of ballasted systems with no roof penetrations) does not require a licensed asbestos contractor. However, it does require that workers are trained in asbestos awareness (as all workers in buildings where asbestos may be present are required to be under CAR 2012) and that risk assessment has confirmed the material will not be disturbed.

If the asbestos survey identifies that the material is not in suitable condition for work to proceed safely, re-roofing is the appropriate solution before solar installation. This creates an additional cost but also an opportunity: re-roofing immediately followed by solar installation removes all asbestos risk, extends the roof life by 25+ years, and enables the full range of solar mounting options on the new roof.

Where asbestos cement is in marginal but acceptable condition, encapsulation is sometimes used as an intermediate solution. Encapsulation involves applying a specialist coating to the AC sheets that seals the surface, binds any exposed fibres, and typically extends the roof life by 10–15 years.

Following encapsulation by a licensed contractor, the treated surface is assessed for its condition and suitability for work activities. In some cases, encapsulated AC roofs can support a limited range of solar installation approaches. However, the penetration and drilling restrictions still apply to the underlying asbestos cement material — encapsulation does not change the prohibition on drilling through AC sheets.

Encapsulation costs typically £15–£30 per square metre applied. On a 5,000m² roof this is £75,000–£150,000. At this cost level, full re-roofing (at approximately £60–£90 per square metre for a standard profiled metal replacement) becomes economically comparable and often preferable, as it provides a 40+ year roof life rather than the 10–15 year extension from encapsulation.

The decision between encapsulation and re-roofing should be made on the basis of the asbestos survey risk rating, remaining roof life, and the overall project economics including solar. We can coordinate this analysis as part of a free site assessment, working with your asbestos specialist and structural engineer.