WLRC

Valleys

Roof valleys are prone to leaks, since they see the majority of water and snow that land on your roof.
Lack of Maintenance in Roof Valleys Roof valleys funnel water and debris down into your gutters. If debris such as leaves and branches build up in your roof valleys, the water cannot flow quickly down and will eventually find its way through your roof. Make sure you clean your roof at least twice a year to clear away this debris.
Open Valleys Valleys should be formed in lead (be a qualified leadworker) on a board laid down the length of the gutter in accordance with Lead Sheet Association guidelines. The metal should be dressed over the entire valley with a turned-back welt on each edge. The edges of the slates cut on the rake must overhang the welt, leaving a minimum 100mm clear width of the metal valley showing in the centre. Wide slates should be used if necessary so that sufficient width is provided at the tail of each slate. Secret valleys are not recommended because of the difficulty in keeping the drainage channel clear.
Mitred Valley A mitred valley is formed by slates close cut and mitred down the line of the valley and laid with metal soakers of sufficient size to lap and bond with the slates of each course and to be nailed at the top edge. Wide slates may be required for dressing, so that sufficient width is provided at the tail of the slates. The slates should be cut in the reverse way to normal dressing so that there is a straight edge on the face of the slate. Mitred valleys are not recommended below 30°.
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