Most Sioux Falls homes do fine with 5-inch K-style gutters. A roof plane bigger than about 700 square feet, a steep pitch, a valley feeding one short run, or gutters that already overflow in hard rain all point to 6-inch. The upgrade adds about $1 to $3 a foot.
What’s the difference between 5-inch and 6-inch gutters?
The number is the width across the top of the trough. A 6-inch gutter carries roughly 40 percent more water than a 5-inch, and it pairs with a bigger downspout.
| 5-inch K-style | 6-inch K-style | |
|---|---|---|
| Roof area it drains | About 700 to 750 sq ft | About 1,050 to 1,100 sq ft |
| Usual downspout | 2×3, about 600 sq ft of roof | 3×4, about 1,200 sq ft of roof |
| Added cost | Baseline | About $1 to $3 a foot more |
| Where it fits | Most single-story homes | Large roof planes, steep pitches, valleys |
Those roof areas are figured at 7.4 inches of rain an hour, the peak five-minute intensity Sioux Falls gutters are sized for.
How do you tell which size your roof needs?
Size follows the roof plane that drains into each run, not the whole house. Measure the plane above the gutter, adjust for pitch, and compare it with the numbers above. A steep roof sheds water faster and catches more wind-driven rain, so it counts as a larger area than its footprint suggests. A steep metal roof is the clearest case. The arithmetic takes about five minutes.
Your gutters are already telling you if they’re undersized. Look for water spilling along the whole length in heavy rain while the outlets are clear and the gutter drains fully afterward. That’s a capacity problem.
Three things look like size problems but aren’t:
- A waterfall at one inside corner. That’s a roof valley dumping into a few feet of gutter. An extra outlet near the corner fixes it for far less than resizing the house. Where the water spills tells you which.
- Water shooting past the gutter. That’s where the gutter sits, not how wide it is.
- Overflow near one downspout. That’s a clog. There are eight common causes of overflow, and size is only one.
Downspouts matter as much as gutter width
A 6-inch gutter on 2×3 downspouts is a wide pipe with a narrow drain. A 2×3 downspout clears about 600 square feet of roof and a 3×4 about 1,200, and either way you want one downspout for every 30 to 40 feet of gutter.
Adding a downspout is much cheaper than upsizing every run, so when a quote recommends 6-inch, ask what it says about outlet count and size too. Deciding between a bigger downspout and another one usually settles it.
What does the upgrade cost?
Seamless aluminum gutters run about $12 to $18 per linear foot installed in Sioux Falls. Going from 5-inch to 6-inch adds about $1 to $3 a foot in 2026. On a 150-foot house, that’s roughly $150 to $450 on top of the job.
The larger gutter also brings larger downspouts, hangers and outlets, so ask for the whole system to be quoted, not just the trough. The rest of the bill breaks down line by line.
Upsizing is not automatic. On a single-story ranch with a moderate pitch and gutters that have never overflowed, 6-inch is money spent on nothing. If the gutters overflow every heavy storm with clear outlets, it’s the fix.
K-style or half-round?
K-style is the standard profile in Sioux Falls. It has a flat back that screws straight to the fascia and a front face shaped like crown molding, and it holds more water than a half-round of the same width.
Half-round is a plain semicircle. With no inside corner, debris moves toward the outlet instead of packing into a crease, so it clogs less. It costs more, needs its own hangers and outlets, and is usually chosen on older homes, often in copper.
The trade sizing chart behind those capacity numbers was originally built for half-round gutters, so the figures for K-style are on the cautious side.
For a Sioux Falls house with heavy summer storms and leaves overhead, the choice usually comes down to leaf load against capacity. K-style carries more water. Half-round stays clearer.
Do gutter guards fit both sizes?
Guards are made to fit specific gutter widths and profiles. A guard cut for 5-inch K-style will not fit a 6-inch gutter, and half-round needs guards made for its curve. If you’re resizing and want guards, price them together so both match. Guard types differ more than the brochures suggest.
Should you change size when replacing gutters?
Replacement is the cheapest time to change size. The hangers and outlets are coming off anyway, and the crew is already set up. Changing size later means paying for that work twice. Our replacement guide covers what a full replacement includes.
Questions about gutter size
Are 6-inch gutters worth it?
They’re worth it on large roof planes, steep pitches, and any run that overflows in heavy rain while the outlets are clear. On a small single-story roof that has never overflowed, they’re not.
How much more do 6-inch gutters cost?
About $1 to $3 a foot more than 5-inch in 2026. On 150 feet, roughly $150 to $450.
What size downspouts go with 6-inch gutters?
3×4 downspouts, which drain about 1,200 square feet of roof each. A 2×3 downspout on a 6-inch gutter limits the whole system.
Will bigger gutters stop my gutters overflowing?
Only if the gutter is undersized. Clogs, a lost slope, a roof valley and water shooting past the gutter all cause overflow that a wider gutter won’t fix.
Is K-style or half-round better?
K-style holds more water at the same width and costs less to install. Half-round clogs less because it has no inside corner. K-style is the common choice here.
Get a quote
If your gutters overflow in heavy rain or you’re deciding between 5-inch and 6-inch, tell us about the job with a photo, and a local gutter contractor will call, text or email to set up a visit. The quote is free.