Generally, valleys are not recommended below a 17.5° rafter pitch, and rarely used in rafter pitches above 60°. GRP valley troughs can accommodate this range, subject to roof area, valley length and pitch differential considerations.
The Danelaw design of dry fix valley trough can accommodate a greater pitch differential and can be used for larger roof areas and longer valley lengths. For further guidance on applications falling outside our standard published criteria, please contact out Technical Department.
