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.
Marley tiles, asbestos and a brand name
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.
Asbestos roof tile 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.
Is asbestos roof felt a real thing, and where is it found?
Yes, and it is one of the products people forget. Bitumen roofing felt was sometimes reinforced with a thin asbestos fibre layer, and it turns up on flat roofs, garage roofs, dormers and outbuildings of the right age, often under later layers of newer felt. It is usually classed as a lower risk bonded product while it is intact, and the risk arrives with the work: stripping, tearing and hot working on it are exactly what releases fibre. So on any flat roof of that era the sequence is a refurbishment and demolition survey before the strip, not after the skip arrives.
How do I tell if there is asbestos on roof sheets or slates?
By the material and the age rather than by a test you can do from the ground. Corrugated cement sheet, cement slates, cement gutters and soffits, bitumen felt with a reinforcing layer, and cement flue pipes are the products, and any of them on a building worked on before 2000 is a candidate. Two clues help: cement sheet has a characteristic six or eight corrugation profile and a chalky, fibrous broken edge, and it is usually bolted with hook bolts rather than nailed. Nothing is confirmed without a sample, and the sample is taken before work rather than after.