A valley is the channel where two roof slopes meet. It carries a large share of the water from both slopes, so it is a hard-working part of the roof and a common place for leaks to start.
What a valley is made of
Valleys are lined with lead, a glass-reinforced plastic (GRP) lining or sometimes a metal tray, with the tiles or slates cut neatly along each side. Some older roofs have valleys lined with felt or have valley tiles. Whatever the lining, it sits beneath the covering, so a failure can be hard to see from the ground.
Why valleys leak
Leaves, moss and debris block the channel and make water back up under the tiles. Lead can split from movement or thin over time. GRP can crack. The edges of the tiles along the valley can break, and the fixings beneath can rust. Sometimes the original lining was simply too narrow or poorly laid.
Repair or relay?
If the lining is in good condition and the problem is a blocked channel or a few cracked cut tiles, a clean-out and local repair may be enough. If the lining itself is split, worn or badly laid, the tiles beside it are lifted, and the valley is relined. Relining involves taking up the adjoining tiles, which is why it is a bigger job than a patch, but it is a more lasting fix.
Keeping valleys healthy
Keep valleys clear of leaves and moss, and have them checked when the roof is inspected. A small amount of maintenance can prevent a leak into the bedroom below.
If you suspect a valley problem, see our Roof Repairs section or call us on 07766 547309.
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