How to Calculate Roof Batten Spacing UK
Published 9 July 2026 · Browse all tools
Getting batten spacing right is one of the most important setting-out jobs on a tiled or slated roof. Too wide and tiles won't seat correctly or may allow water penetration. Too narrow and you waste battens and create unnecessary work. This guide covers the standard UK method for calculating roof batten spacing, explains what tile gauge means, references the relevant British Standard, and walks through a worked example using common interlocking concrete tiles.
Use the Roof Batten Spacing Calculator hereWhat is tile gauge?
Tile gauge is the distance between the face of one batten and the face of the next batten up the roof slope. It determines how much of each tile is exposed — the part you can see from below the eaves. Tile gauge is not the same as the full tile length. It is always less, because tiles overlap each other by a set amount to keep the roof watertight.
Every tile and slate manufacturer specifies a gauge range in their technical data sheet. For standard interlocking concrete tiles, the gauge is typically between 300mm and 345mm depending on the tile model and the roof pitch. Always use the manufacturer's stated gauge range for the specific product you are installing — never guess.
What does BS 5534 say about roof battens?
BS 5534 — Code of Practice for Slating and Tiling — is the British Standard that governs roof batten sizing, fixing, and installation in the UK. Key points relevant to batten spacing:
Batten sizes must suit the rafter spacing and the loading from the tile or slate being used. Common batten sizes for domestic roofs are 38×25mm (for rafter spacing up to 450mm) and 50×25mm (for rafter spacing up to 600mm). Battens must be graded timber — BS 5534 specifies grading requirements to ensure battens can carry the loads imposed by the roof covering. Nail sizes and patterns are specified to resist wind uplift.
The batten spacing calculation follows from the tile manufacturer's gauge specification. But all other aspects of batten installation must comply with BS 5534 and the tile manufacturer's fixing instructions.
The batten spacing formula
- Step 1 — Measure the eaves-to-ridge distance. Measure the straight-line distance from the top of the eaves batten to the underside of the ridge batten in metres.
- Step 2 — Find the tile gauge. Get the recommended tile gauge from the manufacturer's data sheet in millimetres.
- Step 3 — Calculate the number of courses. Number of courses = eaves-to-ridge distance ÷ (tile gauge ÷ 1000). Round up to the next whole number.
- Step 4 — Calculate even batten spacing. Even batten spacing = eaves-to-ridge distance ÷ number of courses.
Worked example
A pitched roof with standard interlocking concrete tiles. The eaves-to-ridge distance is 4.8m. The manufacturer's data sheet specifies a tile gauge of 300mm.
Number of courses = 4.8 ÷ 0.3 = 16 courses. Even batten spacing = 4.8 ÷ 16 = 300mm.
In this example the spacing comes out exactly at the manufacturer's gauge. In practice the eaves-to-ridge distance rarely divides perfectly, so the even spacing will be slightly above or below the nominal gauge — which is acceptable provided it remains within the manufacturer's specified range.
What if the spacing falls outside the manufacturer's range?
If your calculated even spacing falls outside the minimum or maximum gauge range specified for the tile, you have two options.
- Option 1 — Adjust the eaves course. Use a closer-spaced eaves course to absorb the discrepancy, keeping the field battens within the specified gauge range.
- Option 2 — Use a variable spacing. Some roofers use a slightly variable spacing — running at the maximum gauge for most of the roof and tightening up near the ridge to fit. This is acceptable provided no individual course falls outside the manufacturer's range.
Additional battens to allow for
The calculation above gives you the field battens. You will also need: an eaves batten at the bottom positioned to give the correct eaves tile overhang (typically 50mm into the gutter); a ridge batten at the top positioned to suit the ridge tile or dry ridge system; valley battens where two roof slopes meet; and additional courses around any roof penetrations such as skylights or chimneys.
Batten size reference table
- Up to 450mm rafter spacing: 38 × 25mm — most domestic tiled roofs
- 450–600mm rafter spacing: 50 × 25mm — wider rafter spacing or heavier tiles
- Over 600mm rafter spacing: structural calculation required — do not rely on rules of thumb
Use the free Roof Batten Spacing Calculator
Rather than doing the calculation by hand on site, use the Roof Batten Spacing Calculator at /tools/roof-batten-spacing-calculator on this site. Enter the eaves-to-ridge distance and tile gauge, and the tool returns the number of courses and the even batten spacing instantly.
Disclaimer
This guide is for planning and general reference only. Always follow BS 5534, the tile manufacturer's fixing instructions, and seek professional advice for complex or non-standard roofs.