Choosing the right number of roof tiles is one of the most important steps in any roofing project. Whether you are building a new roof or replacing an old one, knowing how many roof tiles per sq metre you need can save you time, money, and stress. Many homeowners and beginners find this topic confusing, but it does not have to be complicated.
We will explain how many roof tiles are needed per square metre, what affects tile coverage, and how to calculate the correct number for your roof.
What is Roof Tile Coverage?
Roof tile coverage means how much area a single tile can cover on a roof. Different roof tiles come in different sizes, shapes, and materials. Because of this, the number of tiles required per square metre can vary a lot.
Some tiles are small and need more pieces to cover one square metre. Others are large and cover more space, so fewer tiles are required. This is why there is no single fixed answer for all roofs.
Average Number of Roof Tiles Per Square Metre
On average, most roofs need between 10 and 60 tiles per square metre, depending on the tile type.
Here is a simple idea:
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Small tiles = more tiles needed
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Large tiles = fewer tiles needed
Let’s break this down by tile type to make it easier.
Roof Tile Types and Their Coverage
Plain Clay or Concrete Tiles
Plain tiles are small and traditional in design. They are often used on classic homes and older buildings.
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Tiles per square metre: around 60
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Reason: These tiles are small and overlap more
Plain tiles are strong and long-lasting, but they require more labour and more tiles to cover the same area.
Interlocking Concrete Tiles
Interlocking tiles are very popular in modern roofing. They are designed to lock together, making installation faster.
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Tiles per square metre: around 10–15
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Reason: Larger size and wider coverage
These tiles are cost-effective and commonly used for residential homes.
Natural Slate Tiles
Natural slate tiles are made from stone and are known for their premium look and durability.
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Tiles per square metre: around 20–25
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Reason: Medium size with less overlap
Slate roofs can last over 100 years if installed properly.
Fibre Cement Slate Tiles
Fibre cement slates are a lightweight alternative to natural slate.
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Tiles per square metre: around 20–25
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Reason: Similar size to natural slate
They are easier to install and more affordable than real slate.
Large Format Roof Tiles
Large format tiles are designed to cover more area quickly.
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Tiles per square metre: around 8–10
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Reason: Extra-large tile size
These tiles reduce installation time and labour costs.
Why Roof Pitch Matters
Roof pitch means how steep your roof is. The steeper the roof, the more overlap is required between tiles to prevent water from entering.
How pitch affects tile numbers
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Low pitch roofs: need more overlap → more tiles
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Steep roofs: less overlap → fewer tiles
Manufacturers always specify the correct pitch for each tile type. Following these guidelines is very important for roof safety and performance.
Tile Overlap and Gauge Explained
What is tile overlap?
Tile overlap is how much one tile covers another. More overlap increases weather protection but also increases tile usage.
What is tile gauge?
Gauge is the distance between rows of tiles. A smaller gauge means more rows and more tiles per square metre.
Both overlap and gauge directly affect how many tiles you will need.
How to Calculate Roof Tiles Per Square Metre
Here is a simple step-by-step method anyone can follow.
1. Measure Your Roof Area
Measure the length and width of each roof section.
Multiply them to get square metres.
2. Choose Your Tile Type
Find out the tile size and coverage from the manufacturer.
3. Use Tile Coverage Information
Manufacturers clearly state how many tiles are required per square metre.
Step 4: Add Waste Allowance
Always add 5–10% extra tiles for:
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Cutting
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Breakage
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Future repairs
Example Calculation
If your roof area is 100 square metres and you are using interlocking tiles:
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Average tiles needed: 12 per m²
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Total tiles: 100 × 12 = 1,200 tiles
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Add 10% waste: 120 tiles
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Final total: 1,320 tiles
This method ensures you do not run short during installation.
Common Mistakes to Avoid
Not checking manufacturer guidelines
Every tile brand is different. Always follow official specifications.
Ignoring roof shape
Valleys, hips, and dormers increase tile usage.
Forgetting waste allowance
Ordering exact numbers can cause delays and extra costs.
Do All Roofs Use the Same Number of Tiles?
No, every roof is different. Factors that change tile numbers include:
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Tile size
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Roof pitch
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Roof design
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Installation method
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Local weather conditions
This is why professional roofers always calculate carefully before ordering materials.
Why Accurate Tile Calculation Is Important
Accurate calculations help you:
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Avoid material waste
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Control project costs
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Prevent delays
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Ensure long-term roof performance
A well-planned roof not only looks good but also protects your home for decades.
Professional Advice vs DIY Calculation
While basic calculations are easy, complex roofs need expert assessment. Professional roofers understand:
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Tile layout
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Structural requirements
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Local building regulations
For large or expensive projects, professional advice is always recommended.
Final Thoughts
Understanding how many roof tiles per square metre you need does not have to be confusing. By knowing your tile type, roof pitch, and coverage details, you can plan your roofing project with confidence. Always rely on manufacturer guidelines, allow for waste, and measure carefully.
A well-calculated roof saves money, time, and future repair costs. With the right information and planning, your roof will stay strong, weatherproof, and attractive for many years to come.