As long as the asbestos sheets are not interfered in any way such as: cutting, drilling, breaking, sanding or any action that would cause asbestos fibres to become airborne, the question is yes.
The usual repairs are:
Cracked sheets, flashing or ridge caps: they are usually sealed with a flexible, self- adhesive wide tape or Wakaflex flexible flashing (see photo below) and sealed with a water-based polyurethane waterproofing membrane enhanced with fibres for strength, prior to encapsulating.
Holes around the screws/bolts that secure the sheets: with time and ground movements the hard steel wears the softer asbestos compound of the sheet enlarging the hole, resulting in water penetrating the roof cavity. They can usually be sealed with a paintable sealant such as Sikaflex.
Can an asbestos roof be painted?
Yes, asbestos roofs can be painted; the process is called encapsulation and consists of the following steps:
- Repair of any cracks or damaged areas that could cause leaks
- Mould kill application to kill any mould spores (a living organism that exists everywhere there is moisture)
- Asbestos sealer/primmer to bind asbestos fibres, preventing them from becoming airborne & at the same time enhancing adhesion
- Application of filler coat is the next step; this has a dual purpose: to iron out any build-up and achieve a smoother finish, plus highlight any enlarged holes around the screws or hairline fractures of the asbestos sheets, flashing and ridges.
- Attend to any issues found after application
- Apply a coat of roof membrane
- Apply 2nd & final coat of roof membrane.
Can you waterproof asbestos roof?
Yes, asbestos roofs can be water-proofed; there are 2 options;
- Encapsulation as per above 8 step procedure
- Use 8 step procedure but replace roof membrane with a water-based, polyurethane, waterproofing membrane enhanced with fibres for strength and seamless finish.
Is it safe to clean an asbestos roof?
Definitely no! asbestos roofs cannot be interfered with in a manner that would result in asbestos fibres becoming airborne. There are heavy penalties/fines for water-blasting or even scrubbing asbestos roofs.