Inner corners, where two walls meet in an L-shape, collect water like a funnel. Gutters here need to be larger or have a special corner box. A regular miter joint just won’t handle the flow.
Outer corners, on the other hand, are easier. You just run a straight gutter past them. But the downspout should be placed after the corner, not before. You want the water to travel a little, then drop.
Downspouts: The Landing Spots
Here’s a hidden rule: place downspouts where they can drain onto a slope or into a dry well. Avoid dumping them onto a concrete patio or a walkway. That’s like pouring a bucket of water on your own foot every time it rains.
A good rule of thumb? One downspout for every 30-35 feet of gutter. Any more, and the water backs up and spills over. It becomes a waterfall, not a drain.
