Is Spanish Slate Good Quality?


How did we all get through Storm Eunice? Phew, it got a bit hairy back there, didn’t it! Did you lose a few roof tiles? Or maybe you had some more severe damage? We’ve been busy this week repairing the mess that Eunice did to people’s roofs, and we are really sorry if your roof suffered in the storm. If you’re now in need of some repairs, you might be wondering which slate is best to repair your roof with. Well, Spanish slate has long been praised as a high-quality, beautiful and durable roofing material, and we can’t help but agree! If you’re interested in Spanish slate, you might want to read more information and compare it with other slates that we use, including Delabole (or rag) slate, Welsh slate, Brazilian slate, or Chinese slate. All of these slates have their different pros and cons and will be useful in different types of reroofing or roof repair.

For hundreds of years, natural Spanish slate has been used on commercial and industrial roofs. It is extremely durable. Spanish roof slates have performed admirably in the face of the unpredictable British weather for hundreds of years, going back to the 1300s.

On a roof, good quality slate is known to survive at least 70-80 years. Some roofers claim that if it is installed properly, Spanish slate can last the life of the building it serves. The majority of slate used in the UK today comes from Spain and is utilised for high-end projects, historical structures, traditional pitched-roof homes, and sustainable construction.

Spanish slate, along with Welsh slate, is one of the most well-known slate variants on the market. Spain is one of the world’s largest producers of the natural metamorphic material. Geologically, Spanish slate is a foliated metamorphic rock formed over millions of years from fine-grained sediments. Quartz, sericite, and chlorite minerals make up the majority of the mineral. Unlike British slate, which comes in a wider range of colours, Spanish slate is often black or grey. Spanish slate is then cut and shaped into roof tiles, cladding, flooring and much more.

The lithotype for Spanish roofing slates is B1, which corresponds to an authentic black-gray slate, fine grain, homogeneous, and with a high fissibility, allowing it to be exfoliated in fine and regular tiles, according to the International Classification of Slate for Roofs (IRSC).

What makes Spanish slate different from other slates?

Slates aren’t all the same, and they don’t all come with the same guarantees. In contrast to slate from other parts of the world, such as China or Brazil, slate generated in Spain is of tectonic origin. It has been pressurised by tectonic forces (the plates of the earth’s surface pushing together).

Spain was amongst the first nation in the world to produce slate. The world’s largest and best tectonic natural slate reserves are found in the country’s north, a location with a long mining history.

Over three-quarters of the slate sold worldwide is thought to come from Spain.

Natural slate has an extraordinarily low water absorption index of less than 0.4 percent, making it ideal for use as a weathertight roofing material. One of the key reasons it can last for hundreds of years with little or no maintenance is because of this. Natural slate is also completely resistant to frost.

Because Spanish slate’s thick structure helps regulate temperature better than plain tiles, residents living or working beneath the roof can go about their days in a more pleasant indoor environment.

Natural slate also has the added environmental benefit of being 100 percent recyclable and releasing zero hazardous compounds into the environment, making it resistant to acid rain, UV light, fire, and rotting. Natural slate re-use accounts for about 3% of the total pitched roofing market in the United Kingdom.

The cost of Spanish roof slates may deter some customers from utilising them. Spanish slate is more expensive than simple tiles or lightweight solutions like steel roofing, even though it is less expensive than Welsh slate.

Depending on the supply, Spanish slate can be difficult to get hold of, so if you do want to use this beautiful material, let your roofer company know well in advance of your project beginning, so they can begin to source the slates for you.


How is Spanish slate turned into roof tiles?

The majority of mining operations are located in the north of the country, in the provinces of Galicia and Castile and León.

The Orense slate was produced from muds that were set down around 450 million years ago and metamorphosed 300–350 million years ago. These deposits are found in middle and upper Ordovician slate strata (the Ordovician is a geological period when fish evolved jaws and plants began to grow on land). Isn’t that amazing to think that the slate on your roof might have been mud whilst the first land plants were growing!

Natural slate is mined and extracted from quarries, with surface quarries being the most prevalent and conventional method of extraction. After the overburden is removed, slate is sawn into enormous flat slabs, which are then chopped into smaller natural slate blocks and shipped to the facility where they will be cut.

The blocks are then hand divided into roofing slates of the proper thickness by expert workers known as “labradores.” After that, all slates are subjected to a final inspection, with each producer having its own set of criteria for selection and quality. For distribution, Spanish slates are packaged vertically in wooden pallets.

High-quality slate from Spain is subjected to rigourous physical and chemical tests to ascertain its quality.

Grades of slate

A quality control team selects the slate piece by piece once the cutting and crafting process is completed, based on several technical and aesthetic requirements. The slate pieces can be categorised into three separate categories using these parameters, which emphasise flatness and width.

R Excellence selection: This is a very strict categorization process that only parts with a high degree of flatness and consistent thickness can pass. This is often regarded as the best natural slate available. Furthermore, it is great for tasks that require a uniform result for a beautiful roof.

H selection: It is distinguished by its high quality and allows only minor variations in the flatness and thickness of the item. These are slate pieces selected by professional installers who are capable of assembling the product into a seamless roof.

Natural selection: This selection consists of slates with higher thickness and flatness variances. The slates have the same technical features as the exceptional selections because they are made from the same natural slate blocks. The natural selection competes on price with artificial slate while maintaining the long life expectancy and low environmental effect that natural slate is known for.

How do Bristow and Reeve use Spanish slate?

Spanish slate is one of the preferred slate of Bristow and Reeve; we favour a slate called Passaro. Where acceptable, this slate can be used as an alternative to Delabole slate on some historical buildings. Softer than a Brazilian, we don’t use grinders to cut Passaro slates, and we can use nails rather than hooks to install the slates. Passaro slate weathers similarly to Delabole slate, as its flecks weather in different textures and shapes. Spanish is soft so it’s fairly durable and not too brittle, meaning it is easier to work with. Passaro slates cost between £2.50-2.60.

Spanish slate is very high-quality, is straightforward to roof with (if installed by experienced professionals) and will stand the test of time. Maybe even against Eunice!