Installation

5-Inch vs. 6-Inch Gutters: Which Columbus Homes Need Bigger

By Columbus Gutter Repair & Replacement · September 25, 2026 · 7 min read

6-inch gutters cost a few dollars a foot more than 5-inch rain gutters. On some Columbus houses that's money well spent and on others it's money spent. The difference is arithmetic you can do from the driveway with a tape measure, so here it is.

What the sizes actually hold

A 5-inch K-style gutter has a cross-section of about 1.2 square inches per inch of length; a 6-inch is about 1.5. In practice a 6-inch gutter carries noticeably more water, and — the part that matters in Columbus — it holds more ice before it overflows behind the gutter onto the fascia.

Downspouts matter more than most people think. A 2x3 downspout drains about 600 square feet of roof; a 3x4 drains about 1,200. Those numbers assume an inch of rain an hour. In a Columbus thunderstorm they need adjusting.

Columbus rain intensity

The sizing tables in the trade handbooks are built for one inch per hour. NOAA's rainfall frequency data for Franklin County puts a 10-year storm at roughly two inches in an hour, and short bursts within a storm run higher than that. So a sensible design figure for Columbus is two inches an hour, which cuts the table values in half:

These are working figures, not code requirements. If you have a code or permit question about your job, check with the City of Columbus Building and Zoning Services or your suburb's building department.

Do the math on your house

1. Measure the footprint of the roof section that drains to one gutter run: length along the gutter times the distance from the gutter up to the ridge, measured flat on the ground (the horizontal projection, not the slope). A 45-foot back wall on a two-story with the ridge 20 feet in gives 900 square feet.
2. Add a pitch factor: multiply by 1.1 for a normal 6/12 roof, 1.2 for a steep 9/12, 1.3 for 12/12.
3. Add anything that drains into that run from above — a dormer, an upper roof draining onto a lower one, a valley. Valleys are the killer: two roof planes funnel into one spot on the gutter.
4. Divide by the downspout capacity to get the number of downspouts you need.

Example, a 2000s two-story in Ballantrae: back run 45 feet, ridge 20 feet in, 6/12 pitch. 45 × 20 × 1.1 = 990 square feet. At the Columbus design rate a 2x3 handles 300, so you'd need four of them; a 3x4 handles 600, so you need two. The builder installed one 2x3. That's why the far corner overflows every July.

Example, a 1960s ranch in Grove City: front run 40 feet, ridge 14 feet in, 4/12 pitch. 40 × 14 × 1.05 = 590 square feet. One 3x4 downspout covers it, and a 5-inch gutter is fine.

The rule of thumb

• Ranch or modest two-story, no valleys draining into the run: 5-inch gutter, 3x4 downspouts, one downspout per 35 feet of run. That covers most of the 1950s–70s housing in Whitehall, Grove City, Reynoldsburg and the older parts of Westerville.
• Two-story with 900+ square feet on a run, or any run taking a valley or an upper roof: 6-inch gutter, 3x4 downspouts, one per 35 feet. That's most of Dublin, Powell, Hilliard's 2000s subdivisions and the bigger houses in Gahanna and Pickerington.
• Steep roofs (9/12 and up), which shed water fast and shoot it over a small gutter: 6-inch regardless of area. Common on the Tudor and colonial revival homes in Upper Arlington and Bexley.
• Mixed: 6-inch on the run that needs it, 5-inch elsewhere. It's a common approach on Dublin replacements: 6-inch on the long back wall, 5-inch on the front and sides. It looks fine from the street because nobody can tell an inch from the sidewalk.

Winter changes the answer

A 5-inch gutter that's adequate for summer rain can still be the wrong choice on a north-facing eave that grows an ice dam every winter. The extra inch of depth on a 6-inch gutter holds more of the melt before it spills behind the gutter, and the bigger opening at the 3x4 outlet stays open longer when the elbow starts to freeze. On houses in Clintonville and Worthington where the north eave has ice-dam stains on the fascia, 6-inch on that side is worth considering even when the roof area alone doesn't require it.

Often the outlet is the cheaper fix

Before paying for a bigger size, look at the downspouts. Many overflow problems here come from a long run with one small outlet at the end. Adding a second downspout halfway along, or swapping a 2x3 for a 3x4, often solves it for a couple of hundred dollars. Upsizing the trough alone, while keeping the same single 2x3 outlet, gives you a bigger reservoir that still drains at the same slow rate.

The larger size earns its money in three places: below a valley, under a steep roof, and on a north eave that ices every winter. Elsewhere, more outlets usually beat more depth.

Mistakes worth avoiding

• Upsizing without changing the downspouts. The outlet sets how fast water leaves.
• Sizing from the front of the house. The back wall of a two-story usually carries far more roof.
• Forgetting the upper roof. A second-story roof that drains onto a lower one adds its whole area to the run below.
• Matching the neighbors. Two similar houses can have very different roof areas per run.
• Skipping the math because the old ones "worked." If the far corner has spilled every July for years, they didn't.

Questions to ask on the estimate visit

1. What roof area drains to each run, and how did you measure it?
2. Which runs are getting the larger size, and why those?
3. How many downspouts will there be, and where?
4. Will any valleys get a diverter or extra outlet?
5. What's the price difference between doing the larger size on one side and on the whole house?

Any estimator should be able to show the numbers. If the answer is "we always use the same size," you're getting a habit, not a design.

How it looks on the house

From the street, the bigger profile is only a little taller on the face of the eave, and most people can't tell the difference. On a small ranch with a narrow fascia, though, the larger trough can look heavy and may not fit cleanly under the drip edge. Ask the installer to hold a sample piece up to your fascia before deciding. On a tall two-story, the larger size usually looks right in proportion to the wall.

A quick self-check

Stand at the corner that spills and count the outlets on that wall. Then look up and note whether a valley or an upper roof drains toward it. One outlet, a long wall and a valley above it is the classic case for more capacity. Two outlets and no valley usually points to a clog or a sag instead.

What it costs

Five-inch seamless aluminum installed is about $9–$12 a foot in central Ohio; six-inch is $12–$16. On a 200-foot two-story that's several hundred dollars more for the whole house in 6-inch, or a couple of hundred more to do only the back run. Upsizing a 2x3 downspout to 3x4 is $15–$25 more per downspout on a new install, and $120–$220 as a standalone repair. The cost page lays it all out, and the replacement page covers how sizing should be handled on the estimate visit. If your current gutters spill at one corner in every storm, why gutters overflow in Columbus rain will tell you whether it's this problem or a cheaper one.