Slate roofs are one of the best roofing products on the market, in my opinion. They are versatile, long-lasting and aesthetically pleasing. In this blog, we will highlight the key performance of slates, different types of slate and best practice on choosing the correct slate for your roofing project.
Slate is commonly used throughout the U.K. and we are lucky to have some great slate mines in Wales that produce some of the best slates in the world. Many houses today are still covered in Welsh slate that are over 100 years old and still fit for purpose. Slate has an extremely low water absorption index which makes it the best product on the market for waterproofing materials. It is also a fully mechanical process and requires no processing or chemical products. These are some of the main reason that slate roofs if installed professionally will last for 100s of years.
Choice of slate
Slates are produced from quarries by splitting the rock and then cutting it down to the sizes we see on our roofs today. As mentioned above some of the best slate in the world is produced in Wales, however, Welsh slate can be on the costly side and most slate we see in Europe and the U.K today come from the Spanish quarry’s. Spanish slate is of a dark colour still of good quality but can have a higher pyrite (fool’s gold) content which over years can lead to rust marks staining the roofs. Spain is the largest producer of roof slates in the world.
Some of the other slates produced across the world are
- North America
All slates mined in these different countries have there own pros and cons but a skilled roofing contractor or architect will be able to best advise you on your project. Different quarry’s also come with different shades of slate that may affect the choice of roof slate if you have a heritage or historic building.
The options to reuse roof slates
Due to there resilience to U.V. rays, frost, and the longevity of slates older building that roofs begin to leak are in most cases due to the timbers decaying. This means the slate is still in good condition and in many cases can be reused keeping the overall cost of the project lower. There is a strong reclaimed slate market in the U.K. so sourcing slate to make up the ones that are damaged tends not to be an issue.
While there is a wide range of roofing products on the market as discussed in our previous blog, Slate is one of the more skilled roofs to lay as there are lots of factors that come into laying a slate roof correctly. You only see approximately 1/3 of the actual slate this is due to the fact slates are laid on bonds that allow water to pass through so the slate has to be double overlapped. Even when cutting a slate, it is important to create a chamfer on the slate (this is achieved by using specialist slate cutters and cutting the slate upside down) this creates a rough edge on the slate and stops water tracking or tailing back up the slate. Sadly, its small thing like this that is missed by some contractors and can affect the roof many years later. Roof slating is a separate discipline in the National federation of roofing Contractors (NFRC). The NFRC are the U.Ks governing body for roofing contractors and 80% of all roof work in the U.K. are carried out by its members. You can see our profile here.
Due to its history in the U.K., many historic buildings have slate roofs (mostly welsh slate) so when a new roof or roof repair are required on these buildings it’s often the case we reuse the existing slate where possible to keep the cost down. Slate is also great for detail work you can cut curved roofs, rounded roofs and some of the most skilled slate roofers can create intricate designs on roofs which is one of the reason slate is one of the most aesthetically pleasing roofs and often favoured by architects.
Slate is, without doubt, the best roofing product in the world but due to the fact you need skilled contracts and the cost of the actual slate, it does make it on the more expensive side. With it outlasting all other roof types though it is still one of the most long-term cost-effective roofs on the market.
If you would like any advice on slate roofing please feel free to contact us