Icopal-Roof-Design

Recommended Headlaps and Sidelaps

Head laps and side laps to roofing underlays should comply with the recommendations of BS5534: 2014: Code of Practice for Slating and Tiling and BS 8000-6: 2013 Workmanship on Building Sites.

Head Laps (recommended minimum)
Pitch Unsupported Fully Supported Vertical
12.5° to 14° 225mm 150mm 100mm
15° to 34° 150mm 150mm 100mm
35° + 100mm 75mm 100mm

 

Detail Laps (recommended minimum)
Pitch Unsupported Fully Supported Vertical
Side lap 100mm 100mm 100mm
Verge 25 - 50mm 25 - 50mm 25 - 50mm
Hips 150mm 150mm   -
Valleys 300mm 300mm   -
Eaves   25mm 25mm
Ridges as table above    

NOTES:
1. Any penetrations to the underlay should be suitably sealed to prevent water ingress.
2. Underlay laps to valleys should comply with recommendations of BS 5534.
 

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