Suspect materials · roof sheeting
Is the corrugated roof on your garage asbestos?
We can't tell you. Only laboratory analysis can. What we can tell you is what asbestos cement roofing typically looks like in Ireland, where it shows up, and what to do before disturbing it.
What asbestos cement roofing is
Asbestos cement roofing combines Portland cement with chrysotile asbestos fibres pressed into corrugated sheets. The asbestos gives the sheet tensile strength, fire resistance and dimensional stability. It was the dominant material for garage, shed, lean-to, farm-outbuilding, factory and warehouse roofs in Ireland from the 1950s until the EU ban took effect in 1999.
What to look for
- Corrugated profile — typically 76 mm or 146 mm pitch, with a regular wave.
- Grey colour, weathered to a paler grey-green over decades. Often with moss, lichen or algae growth on the upper surface.
- Fibrous, slightly chalky texture at any broken edge or cut end — short white fibres visible in the cement matrix.
- Hard and brittle — cracks rather than bends. Old sheets may be cracked from foot traffic, stones, or weather.
- Bolts through ridges — typically galvanised hook-bolts holding the sheets to timber purlins, sometimes with bitumen or felt washers.
Modern non-asbestos fibre-cement sheeting (manufactured after 1999) looks almost identical. The visual cues only tell you the material is suspect — they don't confirm asbestos content.
Where it shows up in Ireland
- Garage and shed roofs on Irish housing built between roughly 1960 and 1990 — extremely common.
- Lean-to extensions and outbuilding roofs on rural and small-town housing of the same era.
- Farm outbuilding roofs — barns, milking parlours, hay sheds. Often the highest concentration in any rural property.
- Industrial and commercial — factory roofs, warehouse roofs, light commercial premises.
- Soffit and fascia trim on some bungalows of the period — flat asbestos cement boards rather than corrugated.
Risk profile
Asbestos cement is non-friable when intact. The asbestos fibres are bonded into the cement matrix and an undisturbed, weathered roof in good condition does not release fibres at significant rates. This is why the HSA position is that intact asbestos cement can often be left in place under a management plan rather than removed.
Risk increases sharply when the sheets are:
- Cut or drilled — releases fibres at the cut surface.
- Power-washed — pressure breaks the bonded surface and washes fibres into runoff.
- Broken — by storms, falling tree branches, foot traffic, or impact.
- Removed without controls — the most common cause of significant exposure.
If you think you have it, what next?
The right next step depends on what you are trying to do:
- Doing nothing for now? Leave it alone. Don't walk on it, don't power-wash it, don't drill into it. Document its presence (a photo and a note in your property file) for the next owner or contractor.
- Planning to remove it? Get a survey first to confirm asbestos content, then engage a permit-holding removal contractor — see the roof removal guide.
- Planning solar PV? Most installers will not work on an asbestos roof. The usual sequence is survey, removal, reroof, install. SEAI grants do not refund the asbestos line.
- Sheets damaged? Don\'t try to patch them yourself. A broken cement sheet is potentially releasing fibres. Get a survey and a removal quote.
Frequently asked questions
How do I tell if my garage roof is asbestos?
You can't tell with certainty by eye — only laboratory analysis can. What you can do is decide whether the roof is suspect enough to warrant testing. Suspect markers: grey corrugated sheeting, slightly chalky fibrous texture, weathered to grey-green with moss, on a garage, shed, lean-to or outbuilding built before 1990. If those markers are present, treat it as asbestos cement until tested and arrange a survey.
Is an asbestos roof dangerous if it is intact?
Asbestos cement is bonded — the fibres are locked into a cement matrix. An undisturbed, weathered roof in good condition does not release fibres at significant rates. The HSA position is that intact asbestos cement can often be left in place. Risk increases sharply if the sheets are cut, drilled, power-washed, broken in storms, or removed without proper controls. Doing nothing to an intact roof is sometimes the right call.
What about modern non-asbestos fibre cement — how do I tell the difference?
You generally can't, by eye. Modern fibre cement (post-1999 in Ireland) uses cellulose, PVA or other fibres in place of asbestos. The visual profile is nearly identical. Sheets manufactured after the EU ban took effect in 1999 should be asbestos-free, but the only way to confirm is laboratory analysis. If a roof was installed during a refurbishment between 1999 and 2005 or so, both materials were on the market — the safer assumption until tested is that it could be either.
Can I power-wash my asbestos roof?
No. Power-washing an asbestos cement roof is one of the most common ways to release fibres. Pressure breaks the surface, mechanical action removes the bonded layer, and water carries fibres into runoff and onto surrounding surfaces. The HSA explicitly warns against power-washing asbestos cement. If your roof needs cleaning, soft-washing with appropriate biocides — or replacement — is the right approach, and any work should be done by a competent contractor.