How to install gutters: the slope, the hangers and the downspouts, step by step
Measure the eaves, mark where the downspouts go (at the corners and about every 30 to 40 feet), snap a line that falls about 1/4 inch for every 10 feet toward each downspout, hang the gutter on hangers 24 to 36 inches apart, then run the downspouts down and send the water 3 to 5 feet from the foundation (Lowe's). Check the fascia first: gutters hang on it.
Anthony Hicks30+ years in construction. Updated November 5, 2026.
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The numbers to work to
| Rule of thumb | |
|---|---|
| Slope | About 1/4 inch of fall for every 10 feet, toward the downspout |
| Hangers | 24 to 36 inches apart, closer where snow is heavy |
| Downspouts | At the corners and about every 30 to 40 feet of gutter |
| Discharge | 3 to 5 feet from the foundation |
These are Lowe’s figures for a typical house; the gutter maker’s instructions come first for its own hangers, joints and sealant.
Step by step
- Check the fascia. Gutters hang on the fascia board, so rotted or cracked fascia is replaced before anything goes up. On a replacement, take the old gutters and hangers down first.
- Measure the eaves. Gutters run along the eaves, the level edges of the roof, not up the sloped rakes. The guide to the rake shows which edge is which.
- Pick the size. 5 and 6 inch K-style are the standard house sizes; a large or steep roof sheds more water and may need 6 inch.
- Mark the downspouts. Put one at the corners and about every 30 to 40 feet.
- Snap the slope line. Start at the high end just under the roof’s edge and fall about 1/4 inch every 10 feet to the downspout. A 40 foot run falls about 1 inch.
- Hang it. Screw the hangers into the fascia every 24 to 36 inches with exterior screws, join the sections and seal the seams to the maker’s instructions, then set the gutter in the hangers.
- Add the outlets and downspouts. Cut the outlet, fasten and seal it, then run the downspout and elbows down the wall on straps.
- Send the water away. Extensions or splash blocks carry it 3 to 5 feet out. Then run a hose in the gutter to check the flow and the joints.
What the code says
The building code mostly leaves gutters to the house. Where expansive or collapsible soils are known to exist, though, it calls for a controlled way to carry the roof’s water, such as gutters and downspouts, and to discharge it at least 5 feet from the foundation walls or into an approved drain (IRC R801.3).
How much gutter to buy
Add up the eaves that drain, then the downspouts: the wall height at each one, plus elbows. A one-story house 40 by 30 feet with gutters on its two long sides has about 84 feet of gutter; four 10 foot downspouts add 40 more. The gutter installation cost guide prices it by the foot in your state, and the roofing calculator gives the eave length with the rest of the roof.
Common questions
What slope should gutters have?
About 1/4 inch for every 10 feet toward the downspout (Lowe’s). A 40 foot run falls about 1 inch end to end.
How far apart are gutter hangers?
24 to 36 inches, closer in heavy snow (Lowe’s).
How many downspouts do I need?
At least one per run, at the corners, and about one every 30 to 40 feet along the gutter (Lowe’s).
Are gutters part of a roof estimate?
They’re lines of their own. Gutters taken down for a reroof are priced to detach and reset, or to replace by the foot, on top of the roofing.