Why Valleys Leak on Winchester Properties
Roof valleys are where two roof slopes meet, channelling a combined water load into a single line. They are the most common source of roof leaks we investigate on Winchester properties — and the most frequently misdiagnosed. When a valley fails, water enters the roof structure at the lowest point and tracks horizontally across the ceiling before appearing internally, often several metres away from the actual failure point. The valley failure is frequently attributed to the wrong roof element as a result.
Lead vs Tile Valleys in Winchester
Winchester properties use two main valley types. Lead-lined valleys — a lead tray fixed along the valley channel — are standard on Victorian, Edwardian and 1930s properties. Lead valleys fail at bay joints, at the tilt fillet detail and at the head of the valley where water load is highest. Mortar valleys — concrete mortar bedded between cut tiles — are found on some post-war properties. Mortar valleys crack as the roof moves and are often the first element to fail on 1960s–70s Winchester housing. Open cut valleys using specialised valley tiles are used on some modern and refurbished roofs.
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