Roof Valleys: Necessary but troublesome!

Roof Valleys! I get MANY  calls every year from people who say that their eavestroughs are "leaking" or that they can't handle heavy rains. Upon inspection, I encounter that the common culprit are roof valleys on a house. Roof Valley's are created when two roofs, running in different directions come together and form a "valley" as seen below:

In today's world of new home designs, the larger the home, the more roof valleys it usually has. Look at the birds eye view of the home below:

Look at the complexities of this roof! Roof Valleys are everywhere! By my count, there are 13 roof valleys on this home! Not only this, but you have roof valleys running into other roof valleys! The valleys allow the home owner to design and build a home that looks absolutely gorgeous! Without them, you could not have a house that has dimensional roofing. All you could have is a straight roof as seen below on a home we just completed in Stoney Creek, Ontario.

This home turned out beautifully. It's a simple design from the 1940's that we did with Pebble clay siding and black eavestrough, fascia, and soffit. Simple roof designs were very common prior to 1980. However, over the years, architects became more clever with their roof designs for three reasons. The first was to make the house more beautiful; the second was to maximize space, and the third was to give added dimensions to the house.

However, roof valleys create enormous problems in regards to water drainage and they also trap debris in areas that have large trees. Look at the diagram below. It shows you the direction the water flows down the roof. You can have a ton of water drain from the roof into the roof valley and the result, in a strong rain storm is a river running down them and into one small section of eavestrough!

You can see how the water runs down the roof and into the valley. The problem is that by the time it gets to the end, you can have hundreds of square foot of roofing trying to fit into 4-6 inches of eavestrough. Now that's a problem! Look at some of these problem valleys people have asked me to come out and troubleshoot for them! These eavestroughs weren't leaking. They just could not handle all the water coming into one small section of eavestrough so the water was shooting over the front of the eavestrough and onto the ground.

I did not do this eavestrough job. They only called me out to try and fix their problem of water over shooting the eavestrough. The splash guards I installed didn't even work in a heavy rain! There was far too much water coming into this eavestrough. Here is another problem job I was called out to inspect.

The above homes are absolutely beautiful and the roof valleys help create their beauty. But you can see for some, valleys are a nightmare when trying to channel water off a roof and into the eavestrough. But the problem does not stop there! If you have mature trees around, they are debris traps! This is because debris blows onto the roof and then the wind travels across the roof in different directions. The wind blows the debris into the roof valleys and traps it there. Just look at these pictures!

The old home designs were simple and there were few problems with rain water and debris being trapped on the roof. The new home designs are complex and with these complexities come problems. We will always have roof valleys and the problems that go with them. In most cases, there are solutions to solve these problems. The most common solution for them is to install a splash guard like I did on the house 4 pictures up. Failing that, the next step is to install a 6" eavestrough and 4x3 downpipes. Regarding the debris being trapped on the roof, the only solution is to clean them out twice per year.

Roof Valleys are a problem, but not insurmountable. If you have troubles with your roof valleys, give The Eavestrough Company a call at 905-902-9424 or visit our website at www.theeavestroughcompany.com