A small river carved the Grand Canyon. What do you think is going to happen with a small river coming out of your down spout onto the roof? The effects are obvious. Debris, mud, and rust are flushed out from the down spout and stain the roof. The cascading water erodes away the roof granules thereby shortening the life of your roof.
The best resolution to this problem would be to have the upper story downspouts be extended to the ground. The drawbacks are that it is more expensive than draining onto your roof, (which is why the builder did it in the first place). Once on the ground, there may not be a safe area to drain the water without creating a hazard or doing damage to the home and landscape.
Some areas of the upper gutters may not be accessible to drain directly onto the ground. Another solution is to have the upper down spout drain directly into the lower gutter system. These are called “Tie-Ins”. They are noticeable, but you can at match the color of the down spout to your roof to make it less visible.
If you are installing gutter caps then you must deal with the upper down spouts. Otherwise, the volume and velocity of water will cause the rain to overshoot at this point. At the very minimum, they must be tied in directly with the lower gutter system. Typically, a hole is cut in the gutter protection panel for the down spout and the area around the down spout is caulked. In some cases, it may not be a good idea to install gutter covers where a large amount of roof and upper down spouts are draining into a small section of gutter.
Proper drainage is important to extend the life of your home. Proper drainage from the upper section of roof will extend the life and looks of your roof. Your gutter cover’s ability to handle large volumes of fast water will be enhanced by tying in the upper down spouts directly into the lower gutters.
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This Post Is From GutterRoof.com’s Gutter Protection Article Section