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Facts About Slate Roofs

Facts About Slate Roofs

What Toronto Homeowners Need to Know About One of the World’s Architectural Beauties

Facts About Slate Roofs Along with clay and thatch, stone is one of the most ancient roof materials,having been used in Europe for hundreds of years. The origin of cleavable slate stones can be traced back the 8th century, quarried from Western parts of England and Wales. They became popular in Canada during the mid-19th century. Indeed, slate tiles can be seen adorning the Craigdarroch in Victoria B.C, as well as Toronto’s University College and one of the oldest churches in the country – St. Michael’s Cathedral. Aside from its historical usage, slate is still made into roofs for commercial and residential purposes today throughout Canada.

What Are Slate Roofs?

Natural stone roofs made up of slate; a metamorphosed, crystalline rock arising from mudstone or shale, which is split into flat, thinner sheets, shingles, and tiles. Slate tends to be formed between converging plate boundaries.

Types of Slate Roofs – Which is Best for Your Home?

Slate is perfect for giving a unique, stately look to buildings. It fits well with Spanish and Mediterranean-styled buildings.

The stone is available in a myriad of colours such as blue, green, black, blue-grey, red, or purple, depending on its source and textures from ranging from rustic to smooth and flat.

The three main types of slate tiles include:

  • Weathering: Colours transform dramatically over time
  • Semi-Weathering: Colours change less drastically than they do for weathering slate
  • Unfading: The pigmentation is maintained over a significant length of time

Slate can be further divided into two categories: hard and soft. Knowing the difference between the two is important when the time comes to replace or repair slate roofs.

Hard Slate: Have a lifespan of 75 – 200 years and are usually of different colours as opposed to black. It’s recommended that you restore hard slate roofs rather than overhaul them entirely if the roof has issues – as this type of slate most likely will have 100 years of life left on it.

Soft Slate: Usually black in colour and compared to hard slate, have a much shorter life expectancy of 50 to 125 years. In the event that this roof experiences problems, it’s probably best to replace it entirely as the costs and efforts spent on repair may not be worthwhile.

Can Slate Roofs Withstand Toronto Weather?


As climate conditions change frequently across the GTA, naturally you’ll want a home which can adapt to all the variations. The good news is that slate is one of the most enduring elements, able to withstand major meteorological damage without even taking on a weathered appearance.

Cold Weather: Slate can take a beating from intense cold, such as is experienced from the worst Canadian winters. It does not absorb water, which means it is ideal for colder areas where it is exposed to snow and ice.

Hotter Climates: It’s also non-combustible, making it a fine option for very dry, hot wildfire-prone locations. The stone reflects heat, rather than absorbing it, thus lowering your energy costs.

Wind: The rigid, unbendable nature of slate makes it a fine option for high-wind climates, especially with proper headlap and nail length. Securing tiles with metal hooks adds to their wind-resistant ability.

Pros and Cons of Slate Roofs – At a Glance


Advantages of Slate Tile Roofs Disadvantages of Slate Tile Roofs
Longevity – these roofs can last over 400 years when properly installed and maintained Expense
Appearance – has a luxurious, elegant and classy appeal Installation and replacement difficulties
Waterproof Fragility
Fire Resistant Weight
Energy Efficient High transport costs
Electrical Insulation properties Requires sturdy structural support
Available in many colours and styles
Low Maintenance
Resistant to mould, mildew, and rot


How to Install Slate Roofs – A Basic Overview

Stainless steel/copper nails or metal hooks are traditionally used to fasten slate shingles. Usually, tiles are wired/screwed to angles of a steel framed roof, or affixed with nails to wooden sheathing, in overlapping strips. It is often laid on or mixed with mortar or asphalt, depending on the climate, for increased durability against external elements.

A bit of advice: try to add slope to the roof – the higher the better – and take other steps to prevent anyone from walking on the roof, as the pieces are easily breakable.

Installing slate is very complex – it’s probably best to leave it in the hands of a reliable roofer, rather than putting yourself at risk and possibly causing further damage to the tiles. Nevertheless, for curious minds, the following provides a basic run-through of the installment process:

  • The first step is always having the length and width of your roof measured; this helps you to determine the measurements you’ll need to provide when ordering your new shingles.
  • When the time comes to buy the roof material, doing research to look for a trusted local supplier is your best plan. For slate, it is best to select an established manufacturer from Canada or the U.S. as importing it from overseas is riskier.
  • Hire a reliable roofing contractor – also known as a “slater”; a person who has expertise and experience with slate roofs.
  • Ensure that the roof deck is properly constructed, so that it can potentially support the slate for at least 150 years. This means using durable solid lumber, such as oak boards and concrete as opposed to cheap constituents, glued/laminated products, and plywood.
  • Have holes drilled or preferable, punched into each piece of slate. Use a tape measure to create chalk lines.
  • Lay out the starter strip, with partial overhang over the roof edge and then the first course.
  • Follow up with the rest of the roof in staggering layers and ridge lines.


Slate tiles are one of the most visually marvellous roof options and their strength and shelf-life make them an excellent roof alternative for Toronto homeowners. We’d love to walk you through your slate roof installation/repair process- contact us today!

Want to learn about other roof styles? Check out our Which is the Best Type of Roofing Material For Me article for more advice.

Looking for a reliable roofing contractor? Look no further! Call us now for a free no obligation estimate at 1.855.582.7263 or fill in the form at the top of the page and we’ll get back to you soon!

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