Plan on at least one downspout for every 30 to 40 feet of gutter, with additional downspouts on steep roofs, large roof planes and below valleys. Standard downspouts are 2x3 inches; 3x4 inch downspouts move roughly twice the water and are recommended with 6-inch gutters and in heavy-rain areas.
Spacing guidelines
- Every gutter run needs at least one downspout
- Runs over about 40 feet usually need two, one at each end
- Add a downspout below valleys that dump water into one spot
- Steep or large roof planes may need closer spacing
Placement
Put downspouts where the ground slopes away from the house and water can spread out, not next to patios that slope back, walkways that ice up, or window wells. Every downspout should discharge at least three to five feet from the foundation through an extension, splash block or approved drain connection.
Signs you need another downspout
- Clean gutters still overflow in heavy rain
- Water overshoots one corner
- One downspout handles a very long run
Frequently asked questions
Can I add a downspout to existing gutters?
Yes. A new outlet is cut into the gutter and a downspout added, usually a quick, inexpensive job.
Are bigger downspouts less likely to clog?
Yes. A 3x4 downspout passes fir cones and debris that would jam a 2x3.
Need a hand?
- Downspout Cleaning & Repair: Clogged, crushed or disconnected downspouts cleared and rerouted so water leaves your foundation.
- Seamless Gutter Installation: Seamless aluminum gutters formed on-site to the exact length of your roofline, in your color.