The right gutter size depends on more than the width of the existing gutter. Roof area, pitch, concentrated valleys, length of each run and the number and size of downspouts all affect how quickly water has to move.
When 5-inch gutters make sense
Five-inch K-style gutters are common on residential homes and can perform well on straightforward roof areas with sensible run lengths and adequate downspout capacity.
When 6-inch gutters are worth considering
Six-inch systems are often a better fit when roof sections are larger, valleys dump a lot of water into one point, long runs have limited outlet options, or the existing smaller system repeatedly overflows during hard rain.
Downspouts matter as much as the gutter
Increasing the gutter size without improving restricted outlets or poorly located downspouts can leave the same bottleneck in place. Capacity should be considered from the roof edge all the way to discharge.
What to compare in an estimate
- Gutter profile and size
- Aluminum thickness and finish
- Hanger type and spacing
- Outlet and downspout size
- Downspout locations and discharge
- Fascia condition
- Leaf protection, if needed