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4 Natural Properties of Slate Roofs

Built in 1835, Elizabeth Bay House was the first building in the new colonial town of Sydney to have a slate roof, made from the Welsh slate ballast from a ship’s hold due to its natural properties.
In fact, although slate had been used since Roman times for roofing in Britain, it wasn’t until the discovery of deposits in the 1840s that slate stopped being such a scarce commodity in Sydney and started to be commonly used.
The Welsh slate used in those early prestigious homes had characteristics that met the challenges of the new climate.
Here are four natural properties of slate that make slate roofs in Sydney a perfect match.
1. Slate’s incomparable beauty
If you’ve ever handled slate, you would have noticed that it comes in a variety of colours. Welsh slate is famous for its variation in colour and the smooth sheen that all slate has – a product of the compression over millions of years of microscopic minerals.
Named after the quarries where they are found, Penrhyn Heather Blue, Penrhyn Heather Red and Cwt-y-Bugail Dark Blue Grey are all famous examples of slate colour. But slate from Canada and Spain is also popular and has its own colouration.
2. Slate’s watertight protection
Slate starts life as a fine, muddy silt of minerals including quartz and pyrite that under millions of years of pressure forms into micas, minerals with a structure that allow them to be separated into sheets by ‘cleaving’ the rock.
These minerals are tightly packed together, making the slices of slate impervious to water. It doesn’t matter how much rain a slate roof experiences, it will remain watertight; probably why those looking for roof replacements in Sydney are attracted to slate tiles.
3. Slate’s fireproof qualities
Unlike wooden shingles, which were the earliest form of roofing in Sydney, slate is fireproof due to its natural properties. Fires that are large enough to affect a number of houses generally make their way from roof to roof, so houses with slate roofs have a naturally built-in protection against fire.
Tests by the US National Slate Association found that a slate-tiled roof withstood attacks by fire, with no slates breaking, warping or cracking, and no fire reaching the underside of the slate-covered wooden test deck.
4. Slate’s unbeatable longevity 
One argument against slate is that compared with lesser roofing materials, it’s costly. But then, what other roofing material comes in many cases with a 100-year guarantee?
That’s the kind of guarantee given by many slate quarries, since they know that the when a slate roof needs repairing, it’s not because of the tiles, but because the substructure has worn or the metal fastenings have deteriorated.
Slate is so durable that it is a natural recyclable roofing material. Stacks of slate tiles can be seen sitting in yards in Europe and America, while the roof’s wooden substructure is replaced. The tiles are then returned to their original positions for another century or so of service.
This look into the properties of slate shows clearly that if you’re looking for a beautiful product that has prestige, is waterproof and fireproof, you need look no further than slate – a thing of beauty that lasts virtually forever.