Asbestos cement roof tiles and slates were made in imitation of natural slate and were fitted on millions of British roofs. They are thinner and lighter than concrete tiles, greyer and flatter than natural slate, and they are frequently mistaken for both. Like every other asbestos product, the identification runs through a sample, and the removal is a controlled strip rather than a demolition.
Telling them apart
Asbestos cement slates are usually a uniform grey, thin, with a smooth or lightly textured face and often two nail holes and a rivet. Natural slate is heavier, splits along a grain and varies in colour across a roof. Concrete tiles are thicker and heavier again. Age and uniformity are the clues; a sample is the answer, and roof tile identification by photograph is exactly where people go wrong.
The Marley question
Marley is a long established British roofing brand and the name is often used as shorthand for the interlocking tiles of a period. Some cement based roofing products of that era contained asbestos and many did not, and the brand on the tile does not settle it. What settles it is an analysis of the tile from your roof, not of a tile of the same name from somewhere else.
Removal
Tiles are stripped whole from the eaves up, lowered rather than dropped, and bagged as hazardous waste. Because the roof is fragile the access has to carry the operatives rather than the covering. Nails and rivets slow the job down, and a slate stripped carelessly breaks, which is why a compliant quote is not the cheapest one.
Leaving them in place
A sound asbestos cement slate roof is not shedding fibres and is often best left alone until it needs replacing anyway. Record it in the register, tell anyone working on the roof, and avoid the things that damage it: pressure washing, walking the covering and drilling for fixings.
Questions people ask about asbestos roof tiles
Do asbestos roof tiles have to be removed?
No. Material in good condition is managed rather than removed, and a roof strip is a disturbance in itself. Removal becomes the answer when the covering is failing or the roof is being replaced.
How do I identify asbestos roof tiles?
Age, uniform grey colour, thinness and the fixing pattern are what raise the question. Only a laboratory analysis of a piece of the tile answers it.
Can they be walked on?
They are a fragile material and should not be walked on. Access equipment that carries the load independently of the covering is part of any competent quote.