Leaking Valleys on a Tile Roof- and Water Overflow:

Water damming is a common cause of tile roof leaks. These leaking valleys on a tile roof are usually associated with the “older” version of valley metals used in roof applications before 2003. Because of various debris caused by dirt leaves etc. these valleys dam up over a few years within metal valleys. The water will often “ride” along the top of the upper edge of a roof tile as they over lay in the valley. This allow water to flow over the edges of the metal valley and onto the roof felt and/or substrate.

Additionally, this damming effect often occurs with the standard (old version) of valley metals combined with the flat roof tiles. Due to the high volume of water accumulation in these concentrated areas during rainy season, the water often flows onto the felt and/or substrate. Eventually, the roofing felt barrier decays: allowing water onto the sheathing substrate. This sometimes causing dry-rot damage or other water damage to your home.

In order to minimize this dilemma many manufactures have designed another tile valley metal called “ribbed” valley.

Below is an excerpt taken from an article about tile valleys, the article was written from the #1 *roof tile manufacture in California.

Ribbed Valley to Avoid Leaking on a Tile Roof

“To prevent the diversion of water over the edges of the valley metal and to stop leaking valleys on a tile roof, new tile specific valley metals have been created that feature built in support ribs that support battens or tiles that protrude onto the valley metal. These support ribs also create defined trough areas that control water flow and prevent lateral diversion of water. Furthermore, the size and frequency of these ribs varies dependent on the length of the valley, volume of water expected and the type of tile installation. Finally, with this style of valley, water can pass uninhibited beneath the tile or batten.” In other words, ribbed valley installation is an ideal choice to avoid leaking on the tile roof.

*Monier-Lifetile, A Boral Roofing Company.