Slate roofs are a very popular choice for residential and commercial properties. Considered one of the UK’s oldest roofing materials, slate offers many benefits, such as durability, fire resistance, and aesthetic appeal. However, with so many types of slate to choose from, how do you choose the right one?
From the notoriously long-lasting Welsh slate to a more affordable solution in Spanish slate, this guide will answer all the key questions about this roofing material. To help you choose the right slate for you, we will assess their pros and cons, and discuss where to find a reputable roofer to install a slate roof.
Contents
- What Is Slate?
- Why Install a Slate Roof?
- What Are the Different Types of Natural Slate Roofing?
- What Are the Different Types of Synthetic Slate Roofing?
- What to Consider When Choosing Types of Slate Roof Tiles
- How Weather and Fire Resistant Is Slate?
- How to Choose the Right Slate Roof Specialist
What Is Slate?
Natural slate is a metamorphic rock that has been a particularly well-liked roofing material for thousands of years. Formed from fine-grained sediments such as mud, natural slate is highly durable, naturally water-resistant, and has a smooth, layered structure that allows it to be split into thin, flat sheets.
Synthetic slate, on the other hand, is a man-made alternative to natural slate, designed to mimic its appearance. Made from materials like recycled plastic or fibre cement, synthetic slates are lighter, more affordable, and can be easier to install than natural slates. Both natural slate and synthetic slate have their pros and cons, which we’ll get into later in this article.
Why Choose Slate For Your Roof?
There are several reasons why people consider a slate roof, such as:
- Long-Term Cost Savings: Although slate has a higher upfront cost, it requires little maintenance.
- Aesthetic Appeal: Slate has a particularly attractive finish, making it perfect for traditional and modern properties.
- Durability: Slate is renowned for being able to last a lifetime, giving your property reliable, long-term coverage.
- Weather Resistance: Slate is particularly hardy against all sorts of extreme weather in the UK, from heavy rain to harsh winds.
- Waterproofing: Slate has natural impermeable properties, helping your property stay dry after long periods of rain.
- Fire Resistance: Slate is known for being fireproof since it is non-combustible, providing an extra level of safety in the event of a fire.
- Increases the Value of Your House: Because slate is such a desirable roofing material (for all the reasons mentioned above) it increases the value of your property.
What Are the Different Types of Natural Slate Roofing?
There are many different types of natural roof slate around, so let’s take a look at what sets them apart from each other:
Welsh Slate
- World-renowned as one of, if not the finest roofing slate available.
- Typically dark blue-grey or heather purple in colour.
- Highly dense, making it exceptionally durable and weather-resistant.
- Quarried in North Wales, particularly in Penrhyn, Ffestiniog, and Cwt-y-Bugail.
Pros:
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Extremely long lifespan, often up to 200 years if cared for properly. -
Low water absorption, making it resistant to frost damage.
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High resistance to weathering and colour fading.
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Adds significant value to properties due to its prestige and durability.
Cons:
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High cost due to premium quality and limited availability. -
Heavy material, requiring strong roof support.
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Can be challenging to source, leading to longer lead times.
Cornish Slate
- Traditionally quarried in Cornwall, but production is now limited.
- Often greenish-grey or blue-grey in colour
- Slightly softer than Welsh slate but still highly durable.
- Naturally textured with an appealing rustic, traditional look.
Pros:
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Unique colour variations and natural texture.
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Good durability with a lifespan of over 100+ years.
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Sustainable and locally sourced in the UK.
Cons:
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Limited availability, due to reduced quarrying activity.
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Slightly more porous than Welsh slate, making it a little less resistant to frost.
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More expensive compared to imported slate.
Spanish Slate
- One of the most widely used slate types due to being affordable, yet still durable.
- Available in a range of shades, from blue-grey to black.
- Less dense than Welsh and Cornish slate.
- Quarried in Spain, particularly from areas such as Galicia, Castille, and León.
Pros:
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More affordable than Welsh and Cornish slate.
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Good availability and easy to source.
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Lighter than Welsh slate, reducing structural requirements.
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Can last 75 to 100 years if sourced from a reputable supplier.
Cons:
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Quality varies significantly depending on the quarry and supplier.
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Higher water absorption compared to Welsh slate, making it more prone to weathering.
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Colour may fade over time, especially in lower-grade varieties.
Canadian Slate
- Quarried mainly in Saint-Marc-du-Lac-Long, Quebec.
- Typically dark blue, grey, or black in colour.
- Very dense with low water absorption, making it a highly durable choice.
- Known for its smooth surface, especially the “Glendyne” variety.
Pros:
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Extremely durable with a lifespan of 100+ years.
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Low water absorption, reducing the risk of frost damage.
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Colour remains consistent over time.
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High-quality alternative to Welsh slate.
Cons:
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Expensive due to import costs.
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Heavy, requiring strong structural support.
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Limited supply in the UK compared to Spanish or Chinese slate.
Brazilian Slate
- Mainly quarried in Minas Gerais, located between Rio de Janeiro and Brasilia.
- Available in a variety of colours, including black, grey, green, and purple.
- Naturally smooth with a consistent surface.
- Hard but relatively brittle compared to Welsh or Canadian slate.
Pros:
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Affordable compared to Welsh, Cornish, and Canadian slate.
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Available in a wide range of colours to suit most properties.
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Generally good durability with a lifespan of 50 to 100 years.
Cons:
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More prone to breakage during installation compared to Welsh and Canadian slate.
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Some varieties have higher water absorption, leading to potential frost damage.
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Quality can largely vary depending on the quarry and supplier.
Chinese Slate
- Quarried in several regions of China, most notably in the Shaanxi province.
- Available in multiple colours, such as weathered grey and blue-grey.
- Widely exported and used as a budget-friendly alternative.
- Variable density and quality, depending on the source.
Pros:
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Very affordable compared to Welsh, Canadian, and Cornish slate.
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Wide availability in the UK.
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Lighter than some other slate types, reducing structural load on your property.
Cons:
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Inconsistent quality as some types have high water absorption, leading to faster weathering.
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More prone to fading and surface delamination over time.
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Shorter lifespan - often 50 to 75 years - compared to premium slates such as Welsh.
What Are the Different Types of Synthetic Slate Roofing?
Man-made (synthetic) slate is often the preferred option for roofing material, as it offers the aesthetic appeal of natural slate, yet is significantly lighter, more affordable, and often more straightforward to install. Here are two of the most common synthetic roofing slates:
Fibre Cement Slate
- Made from a mix of cement, cellulose fibres, and other reinforcing materials.
- Available in a range of different colours and finishes.
- Lighter than natural slate, reducing structural reinforcement requirements
- Uniform in shape and size, ensuring easy installation.
Pros:
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More affordable compared to natural slate.
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Lightweight, making it suitable for a wider range of commercial and residential roofs.
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Easy and quick to install due to consistency in size and shape.
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Resistant to moss and lichen growth, reducing maintenance needs.
Cons:
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Shorter lifespan - typically 20 to 60 years - compared to natural slate.
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Not as visually authentic as natural slate.
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Can be prone to cracking under heavy impact.
Recycled Synthetic Slate
- Usually made from a combination of recycled plastics and rubber.
- Designed to mimic the look of natural slate while being more eco-friendly.
- Available in various colours and styles to suit most properties.
- Lightweight and flexible option.
Pros:
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Environmentally friendly, reducing landfill waste.
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Durable and resistant to weathering, with a lifespan of around 40 to 50 years.
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Lightweight, requiring less structural support.
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Easy to install due to flexibility and consistency in size.
Cons:
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Can be more expensive than fibre cement slate.
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Usually lacks the same premium finish as natural slate.
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Limited availability compared to traditional slate options.
What to Consider When Choosing Types of Slate Roof Tiles
Before choosing your desired type of roofing slate, there are several things to keep in mind that may make your choice a little easier - and ensure you get the right type of slate for your needs.
- Durability & Lifespan: If you want the longest-lasting investment, you’ll be best suited to a natural slate such as Welsh, Cornish, or Canadian slate. As long as they’re looked after properly, these three types of slate can easily last over 100+ years.
Find out how long a slate roof should last in our dedicated guide!
- Cost Factors: Some slates start at just £20 per m², but can range up to £180+ per m². If your budget is tight, synthetic slate or cheaper natural slate, such as Chinese slate, is the most affordable. If you want the best balance between affordability and quality, Spanish slate stands out as a particularly strong choice.
For a more detailed price breakdown, read our slate roof cost guide!
- Aesthetics: One of the most attractive aspects of slate roofing is that you can choose a colour that suits your property. For example, fibre cement slate is available in many colours, Welsh slate often comes in a heather purple, and Brazillian slate can be green!
How Weather and Fire Resistant Is Slate?
Slate is highly durable in extreme weather, resisting water, frost, and wind. Its low water absorption prevents leaks and frost damage, while its high density ensures longevity in more harsh climates. However, to ensure that natural slate is fit for its intended purpose, a broad range of its attributes are tested through the standard BS EN 12326-1:2014. This replaced the previous standard, BS 680.
The three most critical areas of slate testing under BS EN 12326-1:2014 include:
- Water Absorption (W): To test water absorption, slate is submerged in water for 48 hours; if the slate absorbs 0.6% water or less, it will be classified as the highest grade, “W1 (≤ 0,6%)”.
- Thermal Cycle (T): To test oxidation and rust within the slate, six tiles are repeatedly soaked and dried out over 3 weeks, and inspected for corrosion. The best classification is “T1”, where the structure isn't affected.
- Sulphur Dioxide Exposure (S): To test slate resistance to atmospheric pollutants, samples are sealed in an airtight container for 3 weeks and tested with a standard mechanical scraping process to assess any softening from chemical breakdown. The strongest classification is “S1”, where there is no change.
The European standard EN 13501-1 is used to test the fire resistance of building materials, such as slate. This framework assesses and categorises the fire performance of different materials commonly used in commercial and residential buildings. Natural slate, such as Welsh and Spanish, is graded “A1”, meaning the material will not contribute to a fire at any stage.
How to Choose the Right Slate Roof Specialist
Finding a quality slate roof specialist can be challenging, as it requires a deep understanding of both the material and the skills needed for proper installation. Slate roofing is a specialised craft, and only experienced professionals can ensure that your roof is installed to the highest standard, providing the long-lasting durability you’d expect.
A reliable slate roof specialist should have a proven track record, strong customer reviews, and a thorough knowledge of slate types and installation techniques. Look for someone who uses high-quality materials and offers guarantees on their work, ensuring your investment is protected for years to come.
At Empire Roofing, our trusted Oxfordshire-based team is known for our expertise in slate roofing. With years of experience and a commitment to high standards, we’ll ensure your roof is installed properly, and we’ll only use the finest quality slate - offering a solution that truly lasts a lifetime. For a FREE quote and consultation, get in touch with us below.
