Most homes use either 5-inch or 6-inch K-style gutters. The right size depends on how much water your roof sheds during heavy rain.

Larger roofs and steeper pitches push more water into the gutters faster. If you have a big, steep roof, you'll probably need 6-inch gutters to handle the volume. Smaller or flatter roofs can usually get by with 5-inch. Here's how we figure it out: we measure your roof area, check the pitch (how steep it is), and look at where water naturally collects. Then we place downspouts in the spots where water flows heaviest. The goal is to move water off the roof and away from your foundation without overflowing the gutters or overwhelming the downspouts.

One thing to avoid: undersizing your gutters to save a little money upfront. If your gutters can't handle the flow during a heavy storm, water spills over the edge and defeats the whole purpose. It's better to go slightly larger if you're on the borderline.

Common mistake we see: Homes with 5-inch gutters that should have been 6-inch from the start. After 25 years of gutter work in similar conditions, the signs are easy to spot—water pooling near the foundation during spring storms, landscaping erosion below the roofline, or gutters that overflow before the downspouts can keep up.

We see this pattern consistently across Southeast Michigan and Northwest Ohio. Sizing it right the first time prevents all of that.