How do I calculate roof batten spacing in the UK?

Measure the distance between the eaves and ridge battens, then divide it by the number of courses based on the tile gauge specified by the manufacturer. This calculator automates that step using metric inputs and returns even spacing between battens that fits your measured roof height.

What size roof battens should I use?

For many tiled roofs, 38×25mm battens are suitable up to around 450 mm rafter spacing, while 50×25mm battens are often used where rafters are spaced up to 600 mm. The exact size must follow BS 5534 and the tile manufacturer's guidance, especially for heavy coverings or exposed sites.

How many roof battens do I need per square metre?

The number of battens per square metre depends on tile gauge and roof pitch. Once you know the batten spacing from this calculator, you can divide the roof height by that spacing to get the number of courses, then multiply by the roof length to estimate total batten metres and convert to quantity.

Can I use this calculator for slate roofs?

Yes, provided you use the correct gauge for your slate and fixing method. Double-lap slate often requires tighter spacing and may need larger battens than standard concrete tiles. Always check BS 5534 and the slate manufacturer's instructions before finalising batten layout.

Do UK building regulations affect batten spacing?

Building regulations don't prescribe exact batten spacing, but they require the roof structure and covering to meet structural and weather-tightness standards. In practice, that means following BS 5534, manufacturer data sheets and any local planning requirements so your batten layout is structurally sound.

Is this calculator enough for complex roofs?

No. For complex roofs with multiple pitches, valleys, hips or non-standard coverings, this calculator is only a planning aid. Complex designs should be checked by a qualified roofer or structural engineer, and set out carefully on site.

Roof Batten Spacing Calculator (UK)

Calculate batten spacing and course count for UK pitched roofs using metric measurements. Enter your tile gauge and eaves-to-ridge distance to get started.

Tile Type

Tile Gauge (mm)

Roof Pitch (degrees)

Pitch does not change batten gauge but affects tile suitability.

Eaves-to-Ridge Distance (m)

Straight-line distance from the top of the eaves batten to the underside of the ridge batten.

How to use this calculator

Measure the straight-line distance from the top of the eaves batten to the underside of the ridge batten. Record this in metres.
Find the tile gauge from the manufacturer data sheet. This is the recommended batten spacing for that tile, usually expressed in millimetres.
Enter the eaves-to-ridge distance and tile gauge into the calculator. You can optionally include any fixed top and bottom overhangs if your design requires them.
Click "Calculate". The tool will return the number of courses and an even batten spacing that fits between the eaves and ridge, based on the gauge you've provided.
Use the result as a starting point for setting out battens on site, then adjust for specific tile types, manufacturer recommendations and local detailing such as valleys, verges and hips.

The formula

Target number of courses

Number of Courses = Ceiling(Eaves-to-Ridge Distance ÷ (Tile Gauge ÷ 1000))

Even batten spacing

Even Batten Spacing = Eaves-to-Ridge Distance ÷ Number of Courses

Eaves-to-Ridge Distance is measured in metres.

Tile Gauge is entered in millimetres and converted to metres in the calculation.

Number of Courses is rounded up to ensure full coverage.

This method uses the manufacturer's recommended tile gauge as the starting point, then calculates a whole number of courses and an even batten spacing that fits the measured roof height. Final setting out should still be checked against the tile manufacturer's fixing guidance, roof details, and BS 5534 before battens are fixed.

Always round up to ensure complete coverage. Additional battens may be required at the eaves, ridge, and around any roof features such as skylights or chimneys. For complex roofs, also see our roof pitch calculator and tile calculator.

Worked example — interlocking concrete roof tiles

Imagine a simple pitched roof using standard interlocking concrete tiles on 38×25mm battens. The measured distance from the top of the eaves batten to the underside of the ridge batten is 4.6 m (4,600 mm). The manufacturer's recommended tile gauge for this product is 300 mm.

Enter 4.6 m as the eaves-to-ridge distance and 300 mm as the tile gauge. Dividing 4.6 by 0.3 gives 15.33, which rounds up to 16 courses. An even batten spacing for 16 courses over 4.6 m works out at 287.5 mm between each course. You now have a clear spacing pattern for your battens that fits the measured height of the roof while staying close to the manufacturer's gauge. On site, you would still check the first few courses against the physical tiles and adjust slightly if needed, but this calculation gives a reliable starting point for setting out.

UK standards and guidance for roof battens

In the UK, roof battens and their spacing are covered by BS 5534 – Code of practice for slating and tiling. This standard sets requirements for batten dimensions, grading and installation to ensure the roof can withstand wind uplift and other loads. As a rule of thumb, rafters are often set at centres not more than 600 mm, and commonly used batten sizes include 38×25mm and 50×25mm depending on span and covering.

The calculator on this page helps you plan even spacing and course counts, but it does not replace BS 5534, the tile manufacturer's fixing instructions or structural design. Always check your batten sizes, nail pattern and fixing details against BS 5534 and the specific product data sheet for the tiles you're using. For more context on roof geometry, see our construction tools hub.

Typical batten sizes for pitched roofs (indicative only)

Rafter spacing (approx.)	Common batten size	Typical use case
Up to 450 mm	38 × 25 mm	Many tiled roofs with moderate spans and loads
450–600 mm	50 × 25 mm	Roofs with wider rafter spacing or heavier coverings
Over 600 mm	Consult structural engineer	Spacing and batten size should be calculated; do not rely on rules of thumb

These values are indicative to illustrate how batten size relates to rafter spacing. Always follow BS 5534 and manufacturer specifications for your particular roof design.

Roof batten spacing FAQ

Related tools

Rafter Length Calculator UK — calculate rafter length from span and pitch
Tile Calculator — estimate tile quantities for floors and walls
Roof Pitch Calculator UK — convert rise and run into angle and pitch ratio
Roof Tile Calculator — work out gauge, tiles per m² and total tiles for your roof

Disclaimer: This Roof Batten Spacing Calculator UK is provided as a helpful planning tool only. It does not replace BS 5534, manufacturer fixing instructions or professional design. Always confirm batten sizes, spacing and fixings against the relevant British Standards and product data sheets, and consult a qualified roofer or structural engineer for complex or high-risk roofs.