How to tell if your roof is asbestos (without touching it)

Somebody said it in passing. A neighbour, an estate agent, a plumber who went into the roof to move a geyser. They looked at the grey corrugated sheets, sucked their teeth, and said the word. Asbestos. And now every time you pull into the driveway you look up at it.

Here is what usually happens next. You Google it, and every single result is a removal company. Every one of them tells you the same thing: it is dangerous, it must come off, it is licensed work, here is a number to call. Nobody tells you what it costs. Nobody tells you the sheets on your roof are almost certainly not doing you any harm right now. And nobody, anywhere, mentions the option that most of the developed world has been using for thirty years, which is to seal the sheets where they are and leave them alone.

So before you spend a cent, work out what you actually have. You can do most of that from the ground, with your phone, in about ten minutes.

Asbestos cement sheeting was the default roofing product in South Africa for decades. If the house went up between roughly 1950 and the late 1980s and it still has its original fibre cement roof, the odds are high. Manufacture wound down through the 1990s, and the use, manufacture and import of asbestos was prohibited here in 2008. So a fibre cement roof installed after about 2000 is almost certainly a modern asbestos-free product, and a fibre cement roof on a 1972 Durbanville house that has never been re-roofed is almost certainly not.

That matters because the two products look nearly identical from the ground. Same corrugation. Same grey. Same texture. Modern non-asbestos fibre cement was designed to replace the old stuff on the same battens, in the same profiles, and it did its job. You cannot tell them apart by staring at them, and anyone who says they can tell for certain from a photograph is guessing.

What you can do is stack up the indicators until the picture is clear enough to act on.

1. 1Profile. The old sheets came in a small number of standard corrugation profiles, most commonly a big six-corrugation sheet roughly 1.09 m wide. Deep, widely spaced, almost lazy waves are a period signature.
2. 2Fixing method. Look at the ridge line and the sheet overlaps. Original asbestos cement was almost always fixed with hook bolts or drive screws through the crown of the corrugation, often with a lead or bitumen washer. Modern sheeting tends to use different fixings and neater caps.
3. 3Colour and weathering. Old sheets weather to a chalky pale grey with dark biological staining along the shaded overlaps, and they often carry a thin green or black film of lichen and moss on the south side. Modern sheets weather more evenly and stay closer to their original tone.
4. 4Edge condition. Cut and drilled edges on old sheets tend to fray into visible fibrous whiskers. On a modern sheet the edge goes powdery and crumbly instead. This is the single most telling detail, and you can usually see it at a gable end with a phone zoom.
5. 5The underside stamp. If you can get into the roof space safely, shine a torch on the back of a sheet near the eaves. Manufacturers stamped their sheets. Names to note are Everite, Nutec, Fibrecem and Marley. A stamp reading NT or Nutec with a date after the mid 1990s points to a non-asbestos product. No stamp at all on an old roof is common and tells you nothing either way.
6. 6Related materials. Asbestos rarely came alone. Flat sheet ceiling boards in the garage or outbuilding, a corrugated carport, old flue pipes, downpipes, a rainwater gutter that rings like ceramic when tapped, and lagging on old pipework are all from the same era and the same product families. If you have three of those, the roof is very likely part of the set.

Asbestos harms people when its fibres become airborne and get breathed in. That is the whole mechanism. Fibres locked into a hard cement matrix, sitting five metres above your head, outdoors, in the wind, are not in your lungs. The risk profile changes completely the moment somebody cuts, drills, breaks, grinds, sands or pressure washes a sheet, because those are the actions that liberate fibre.

Which produces the uncomfortable truth at the centre of this whole subject. The single most fibre-releasing thing you can do to an asbestos roof is take it off. Removal means unscrewing, lifting, cracking, dropping and loading hundreds of brittle sheets. It is done properly by licensed contractors with containment, controlled wetting, protective equipment and registered disposal precisely because it is the dangerous option. Not because the roof was dangerous while it sat there.

Undamaged asbestos cement, left alone or sealed, is a managed material. Broken asbestos cement is a hazard. The work is what creates the risk, not the roof.

This is why the South African regulations do not tell homeowners to strip every asbestos roof in the country. They tell you to identify it, assess its condition, and manage it. Managing it in good condition means leaving it undisturbed and, ideally, sealing the surface so that weathering stops releasing anything at all. Removal becomes the required route when the material is badly degraded, or when it has to go because the building is being altered or demolished.

Encapsulation is legal, it is recognised internationally as a valid asbestos management method, and on an intact roof it is the option that disturbs the least. It is also the one nobody advertises, for a reason that has nothing to do with safety and everything to do with money. There is far more revenue in a strip and re-roof than in a coating, and the companies that hold removal licences are not in the business of talking you out of a removal.

Whether you call us or somebody else, the assessment is where the value sits. A quote that arrives without anybody going up on the roof is not a quote, it is a guess with a number attached.

• Did they physically get onto the roof, or at least onto a ladder at the eaves with photographs to show you?
• Can they describe the condition of the sheets in specifics: which sheets are cracked, which fixings have failed, where the sheet has gone soft?
• Did they mention pressure washing? If they did, walk away. See the article on why that is the worst possible preparation on this material.
• Did they explain when removal would be legally required rather than optional?
• Is the scope written down, with the number of coats, the products by name, and what happens to the fixings and the cracks?
• Does the price include the ridge, the gutters, the flashings and the penetrations, or are those going to appear later as extras?

Ask those six things and you will very quickly find out who has actually done this work before.

We come out, get on the roof, photograph every sheet and every detail, and write down what we find. If the sheets are sound, the recommendation is encapsulation: a controlled low-pressure clean and biocide treatment with no high-pressure water anywhere near the material, brush-applied treatment of hairline cracks and every fixing point, then the full liquid rubber system taken over the field of the roof, up the flashings and into the details in three coats.

What you get out of it is a roof that no longer leaks, a surface that no longer sheds anything into your garden or your gutters, a large reduction in roof temperature because the finish is reflective, and a written guarantee on the system. What you do not get is a bill for a new roof.

If the sheets are not sound, you get told that instead, and we point you at somebody licensed to take them off.