The Corodrain D Type Universal Valley Trough is a narrow valley trough for use with single lap tiles in limited applications. There is a standard (type:HD) and heavy duty (type:DX) option. The valleys incorporate a 35mm sanded strip for the mortar adhesion. ApplicationSuitable for use on roofs with pitches from 17.5 to 55.Can accommodate a maximum difference between two rafter pitches of 15.Designed for use with interlocking tiles, can also be used with natural and manufactured slate.PropertiesLength: 3m.Width: 410mm.Weight: 1.83kg per m2.Thickness: 1.3mm.Colour: grey / blue.Material: GRP - high quality unfilled polyester resin with glass fibre reinforcement.Valley selection table Roof area less than 25m2 Roof area 25m2 to 100m2 Rafter PitchValley TypeMax. Valley LengthValley TypeMax. Valley LengthMinimum Lap Length17.5-22B / D7m--350mm22.5-29A / B / D7mB / D14.5m300mm30-34A / B / D7.5mB / D15m200mm35-39A / B / D7.5mB / D15.5m200mm40-44A / B / D8mB / D16.5m150mm45-49A / B / D8.5mB / D17m150mm50-55B / D9mB / D18.5m150mm