When you picture gutters on a house, there’s a high likelihood that the type you visualize is K Style, which makes sense because it’s the single most popular variation installed in North America. The typical size of K Style gutters installed is 5 inches, but in recent years the demand for K Style 6 inches is growing rapidly. The main reason is ability to carry more water flow.
If your roof’s plane is 600-800 square feet, you should be fine with having 5-inch gutters. The plane refers to one complete area, which includes four edges, typically one side of a gable or hip. On the other hand, if your roof’s plane is 1,400+ square feet, we recommend putting on 6-inch gutters as this results in double the water amount going into your gutters.
When choosing the gutter, you may want to take the size of your fascia boards into consideration as well. The wider the fascia, the smaller the gutter will look. So, if your fascia is 1”x6” you are most likely going to install 5-inch gutters. If your fascia is 1”x8” or 1”x10” you are going to need 6-inch gutters to keep everything looking proportional.