The above photo is what roof tilers call a “mitred valley.” Some Melbourne roof tilers used to use this method for tiled valleys, it is becoming less common and is NOT recommended. Underneath the tiles, the valley metal sheeting is completely covered, blockages will form under the tiles, this will restrict water-flow. This is a major problem just waiting to happen, it’s extremely difficult to clean out blockages and the valley metal will rust quickly. Leaves and tree foliage will work their way in between the joins of the tiles and be almost permanently trapped there. For roofs like this our gutter cleaners will need to move the valley tiles to access the debris. Even if you have a creeper growing over your mitred valleys our gutter cleaner professionals will do their best.
Why did the builder install mitred valleys on your roof?
For terracotta tiled roofs, “mitred valleys” are just a really bad idea, this method is used to save the tilers the trouble of having to cement the valleys but causes a much bigger problem. The valley tiles in the above photo should’ve been grinded back so that the metal sheet underneath is visible. Ask about our valley seal installation!
For some roof types, like asphalt shingles or terracotta shingles, mitred valleys are the norm. But we strongly recommend against using mitred valleys in terracotta tiled or concrete tiled roofing. In old heritage roofing, some other valley types are called “laced valleys” and “swept valleys”.