The original flat-profile concrete interlocking slate that makes the roof easy to build even at pitches as low as 17.5 providing a cost effective roof. The original flat-profile concrete slate with interlocking edges that make the roof easy to build even at pitches as low as 17.5. It provides a cost-effective slated roof effect. Properties Size: 430mm x 380mm. Minimum pitch: 17.5. Maximum pitch: 44. Miniumum headlap: 75mm. Maximum headlap: 125mm. Minimum gauge: 305mm. Maximum gauge: 355mm. Coverage: 8.2 slates/m2 - 355mm guage. Weight: 6.34 tonnes/1000. Batten size: 38mm x 25mm - rafter centres up to 450mm. 50mm x 25mm - rafter centres up to 600mm. Battens required: 2.82m/m2 - 355mm guage. Slate finish: smooth - through coloured. Certification BBA certified.