| Education

Slate? It’s a Date!

But what do we know about slate?

There is Slate and then there is Slate (good and bad).

Most Slate is strong and long-lasting, though some slate can be very low in quality and the opposite. This can spell problems in the short-term future, in regards to the longevity of your Slate roof.                            

All this can be rather confusing when purchasing new Slate, so we will attempt to educate you a little.

What is Slate?

Slate is rock, it is of the earth!

  • It contains mainly quartz muscovite or illite, along with minerals like chlorite, biotite, hematite and pyrite (clay or volcanic ash in essence)
  • It is Fireproof, waterproof, natural and will last for centuries (if good quality).
  • It is quarried for many purposes, though for roofing it is split into thin layers.

The roofing industry has adopted a rating scale to determine the quality of slate, this rates slate as S1, S2 and S3.

The main factors considered for the quality of slate and its longevity are acid resistance, strength and the ability to absorb water.

S1 = “The hard ones”
  • 75+ years
  • High acid resistance, low water absorption and high strength.
S2 = “Not so hard”
  • 40 to 75 years
  • They sit in the middle and are still fairly reliable.
S3 = “try hards”
  • 20 to 40 years
  • The lowest of quality and worth staying away from if you want longevity.

Most popular roofing slates used in Australia are:

Welsh slate – Known as the best slate in the world and usually the most durable, they will also cost you a pretty penny to acquire.

Canadian slate – Quickly becoming the most popular roofing slate in Australia and a great substitute for the Welsh slate, costs less and has a good consistency for quality.

Spanish slate – The most used and produced in the world, though can be hit and miss for quality. Be looking for “Cafersa” or “Forna” if you go down this road.

You can get many other types of slate for your roofing needs, however we have no experience with these and do not wish to give information without experience.

Always speak to a professional and be sure you are receiving the right advice or product you have been quoted for.

Slate roofing is for life, so make sure to use someone who is passionate about the art.

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