Chances are, at some point in your life, you have heard the term ‘valley’ referred to in the context of your roof. In fact, if you’ve read our last Professional Roofers blog post all about flashing, you definitely read about it there! So, if you’ve been following our series on the important fundamental aspects of a roofing system, the question begs to be asked – what is a valley and why is it important enough for us to dedicate an entire blog to it? Why, I’m so glad you asked!
As we briefly explained in our last blog post, the valley of your roof is the internal angle that is formed when two sloping roof planes meet. If you’re having a little difficulty grasping what that means, check out our Facebook Page to review some roof photos and then think about the term ‘valley’ in the traditional sense, where it is the low ground between two large hills or mountain ranges. The same can be said in relation to your roof – it is the low point between two slopes of roof (ie. roof hills).
If your roof was constructed correctly, you should have some form of flashing covering the entire length of the valleys on your roof. If you’re unsure of what flashing is, please see our last blog post for clarification. The valley on your roof is one of the most sensitive areas on your home to water damage – since it is the low point between two slopes, rain water will collect here and flow down into your rain gutters. Because of this, this area sees way more water than pretty much any other area of your home, with the exception of your eaves troughs and downspouts.
If you have a shingled roof, as most Torontonians with a sloped roof tend to have, then you will have one of two kinds of valleys on your home: closed or open. The closed variation is a flashing that has been completely covered with shingles, while in the open variation will have the flashing completely exposed to the elements. When you research this topic online, you will likely find people who prefer one of these methods of the other and they will give their reason. Proponents of the open version say that an open flashing allows the rainwater to move away from the roof faster; since it isn’t bogged down by the friction shingles invariably create. The open method is also cheaper to install, as you require less materials.
Proponents of the closed variety; however, say that while the rainwater might move off of a roof faster with exposed flashing, it certainly does not protect your roof as well. When you leave the edges of your shingles exposed, instead of covering and overlapping them as you would in a closed system, you risk water penetrating up underneath the shingles, especially during heavy rainstorms or after a snow thaw, both of which Toronto can easily experience several times throughout the year. It might cost a little more in materials (around 150-500$ on average depending on the home and material); however a closed system simply performs better. For this reason, Professional Roofers proudly supports the closed system of valleys. We want our customers to be completely satisfied after every roofing job, we don’t want them calling us in need of repairs months later when we could have easily avoided the problem at the time of installation!