We often come across box gutters and valleys on conservatories which have been incorrectly formed or not catered for at all. If lead lined, the lead in a box gutter or valley expands and contracts with heat over time and if not fitted correctly this will lead to stress cracks forming in the lead and an entry point through which water will penetrate resulting in a leaky conservatory.
Visit the Mark George Conservatories website for more information on Conservatory Box Gutters