Asbestos Siding and Transite Panels in Windsor

That grey, slightly wavy shingle siding on older Windsor houses, garages and additions is probably asbestos cement, usually called transite. It was made by mixing asbestos fibre into cement, which produced a board that was cheap, fireproof and effectively rot-proof. Plenty of it is still on Windsor buildings eighty years later, doing its job. Intact transite left alone is low-risk; the hazard shows up when it is cut, drilled or snapped, the disturbance Health Canada flags as releasing fibres, and the reason O. Reg. 278/05 requires the material to be identified before any work that would break it.

Testing a siding or panel material costs $200 to $350 for one or two samples, with results in 2 to 3 business days.

How to recognise it

Shingle siding. Rectangular shingles roughly 12 by 24 inches, often with a slightly wavy or textured bottom edge that imitates wood grain. Grey is most common, though it was painted in every colour over the decades. The tell is thickness and hardness: it is a rigid cement board, not soft like vinyl or springy like aluminum.

Corrugated or flat panels. Transite sheet turns up on garages, sheds, carports, farm outbuildings across Essex County, and as flashing or backing behind stoves and furnaces.

Sound and edges. Asbestos cement rings hard when tapped, closer to a roof tile than a plank. Broken edges show a dense, chalky grey cross-section with fibre visible, not the layered wood fibre of hardboard.

The nail pattern. Shingles were typically face-nailed with two visible nails per shingle, and holes were pre-drilled because the material cracks if you nail through it cold.

Where it turns up in Windsor. Wartime and postwar housing across the city, garages behind the older streets in Ford City and Sandwich Town, additions and porch enclosures added in the 1950s and 60s, and outbuildings throughout Essex County farmland.

Why intact siding is genuinely low risk

Asbestos cement is non-friable. The fibre is locked in a hard cement matrix and cannot easily be released while the board is whole and painted. Siding sitting on a house releases essentially nothing, which is why removal is rarely the automatic answer.

Risk starts with mechanical damage, and the list of things that cause it is short and specific:

• Cutting, sawing or grinding the board (a power saw through transite is the worst case)
• Sanding or aggressive scraping to prepare for paint
• Pressure washing, which erodes the surface and drives fibre into the wash water
• Drilling without care, particularly dry drilling at speed
• Smashing shingles during demolition, or dropping them off a roof into a bin
• Long-term weathering that leaves the surface chalky and eroded

Pressure washing deserves its own warning because it feels harmless. It is a common way Windsor homeowners disturb asbestos siding without ever touching a tool.

What testing involves

We take a small fragment, usually from an edge or an already-broken shingle so nothing new needs cutting, wet it first, seal and label it, and send it for lab analysis. Where the siding is painted in several layers, the paint itself may be worth a separate lead test if the house predates 1980, which is a different hazard often found on the same wall.

Cost is $200 to $350 for one or two materials. Full breakdown on the testing cost page.

Your options if it is positive

Leave it and maintain it. Entirely legitimate. Asbestos cement siding in good condition can stay indefinitely. Paint it with a brush or roller rather than sanding first, and it will keep doing what it has done for decades.

Side over it. Common and cost-effective: insulation and new siding go over the existing board, encapsulating it. No abatement, no disposal fees. Document it so future owners and trades know what is underneath.

Remove it properly. Because it is non-friable, careful removal of whole shingles with hand tools and wetting is generally lower-category work than friable materials like pipe wrap. Shingles are removed intact, not broken, then wrapped and taken to a facility that accepts asbestos waste. Windsor and Essex County disposal has specific requirements and tipping fees, and no ordinary landfill run will do.

What you must not do is take a circular saw or a grinder to it, or pressure wash it clean before painting.

Signs to test first

• Re-siding, re-painting, or insulating an older Windsor home
• Any plan involving cutting openings for windows, doors, vents or a new service entry
• Demolishing a garage, shed or addition
• Storm damage that has cracked or broken shingles
• Buying a house with grey cement-look shingles
• A contractor who has quoted the job without mentioning testing (worth asking why)

Common questions