Valleys are those areas on the roof where two slopes meet. They require a bit of extra care when installing slate roof tiles and shakes because you usually have to cut the tiles for them to fit. Before doing any reshaping and cutting of tiles, you have to decide upon the types of valleys you want for the roof. They can be either open or closed and both options have their differences.
Open valleys have a visible strip of metal flashing where the tile on both slopes ends.
Closed valleys (pictured) are closed where the metal is not visible. While there are some roof coverings that don't require metal flashing for closed valleys, DaVinci Roofscapes requires a self adhered membrane as underlayment, and copper, aluminum, or painted metal for open or closed valleys.
Costs can vary slightly for each type of valley, but the main difference may come down to appearance. If you would like a roof with an even, blended look, you may want to go with closed valleys as the tiles can appear to weave into each other. On the other hand, the right type of metal flashing in an open valley can provide a distinguished look to any home.
What type of valleys do you have on your roof? Tell us about your valley preference in the comments.