Slate Roofing near you

Natural slate is quarried rock split into thin sheets along its grain, and its quality depends on where it comes from. Hard, dense slate can stay sound for generations, while softer slate weathers faster, flakes or loses its colour. Pieces vary slightly in thickness and shade, which gives a real slate roof its texture, and a skilled slater sorts them so the courses stay even.

Synthetic slate is moulded from polymers, rubber or composite blends, often with recycled content. It is generally much lighter than stone, easier to cut and fasten, and less likely to shatter underfoot or when a branch falls. Its look up close, colour stability and long-term record depend on the product, so compare the manufacturer's documentation, fire and impact ratings and warranty. Heritage authorities may refuse a substitute on a protected building.

Natural slate is one of the heaviest coverings you can put on a house, and a Canadian roof must also carry months of snow on top of it. Rafters, trusses and decking sized for asphalt shingles may not be designed for that combined load. Before converting an existing roof to natural slate, or to a heavier synthetic product, have a structural engineer check the framing and say whether it needs reinforcing; see our structural engineers page. Changing the structure may also require a building permit, so check with your municipality.

The deck matters too. Slate is nailed, so the sheathing has to be sound and rigid and hold nails firmly for a very long time. When an old slate roof is restored, the roofer should report rotten boards or sagging rafters found as slates are lifted, and the engineer should see them before work continues.

The stone is rarely what fails first. On an old slate roof, leaks usually come from the metal and fasteners around it, so a slate roof should be built or restored with materials meant to last as long as the slate.

A cracked, chipped or missing slate can usually be replaced on its own. The roofer slides a thin tool called a slate ripper under the course above to cut the nails holding the broken piece, inserts a new slate of matching size, thickness and colour, and secures it with a slate hook fixed between the slates below, or another accepted method. Done well, the repair is nearly invisible. Salvaged slate from the same source is often the best match on an old roof, so ask whether the roofer keeps some or can find it.

Flashing repairs take more work. Replacing worn flashing at a chimney or valley usually means lifting the surrounding slates, installing new copper flashing and relaying the same slates without breaking them. Tar or caulk smeared over a slate leak is a warning sign: it hides the problem, traps water and makes a proper repair harder.

Replacement becomes the question when slates are flaking or sliding across the whole roof, or when most of the nails have failed. Even then, sound slates are often removed, sorted and relaid over a new deck, underlayment and flashing, keeping the original look.

Slate cracks under a person's weight and is treacherous when wet, so a proper inspection is done from the ground with binoculars, from a ladder at the eaves, or from scaffolding or a lift. When a roofer must reach the slates, they use hook ladders that spread their weight and work with fall protection. From the ground, look for:

Slate is hard and smooth, so snow tends to let go in heavy slabs, often all at once when the sun comes out after a storm. Those slabs can tear off gutters, crush lower roofs, shrubs and railings, and injure anyone below a door or path. Snow guards break up the snow and hold it on the roof so it melts away gradually.

Guards are set in rows or staggered patterns across the lower part of the roof, with more on long or steep slopes. They can go in with a new roof or be retrofitted, slipped between existing slates and fixed without cracking the stone. Because they keep snow on the roof, the layout should take the structure into account. Clearing snow from a slate roof is a job for a professional crew, never for a homeowner with a shovel.

Slate is often a defining feature of the heritage buildings it covers. In Quebec, the government's page on heritage work explains that classified properties, and buildings in declared or classified heritage sites and protection areas, need authorization from the Ministry of Culture before they are repaired or their appearance changes, while municipalities set the rules for cited properties. Switching from natural slate to another material changes the appearance, so confirm your building's status before choosing. Across Canada, the Standards and Guidelines for the Conservation of Historic Places in Canada, the national benchmark administered by Parks Canada, favour repairing historic materials and, when replacement is unavoidable, matching the originals.

In Quebec, a roofer needs an RBQ licence with specialized contractor subclass 7.0, which covers insulation, waterproofing, roofing and siding; check it in the RBQ registry. The licence says nothing about slate skills, and many general roofers don't take on slate: it calls for different tools, techniques for cutting and nailing stone, and ways of working on a roof without walking on it. Ask to see slate roofs the company installed or repaired a few years ago.