For most houses around Knoxville, K-style is the right gutter, and on a big or steep roof, 6-inch is the size I'd lean toward. Half-round still has its place, mostly on older houses where the look matters as much as the water.
What's the difference?
Look at a gutter from the end and you'll see it. A K-style is flat where it meets the fascia board and flat along the bottom, with a front of curves and steps that looks a lot like the crown molding in your living room. A half-round gutter is just what the name says: half a circle, open on top, usually with a rolled lip along the front edge.
That shape difference drives most of what follows. The flat back lets a K-style fasten straight to the fascia, with hangers hidden inside the trough. A half-round hangs from brackets, either screwed to the fascia or strapped to the roof deck under the shingles.
Why K-style is on most houses
K-style is the shape you'll see on most houses built in the last few decades, and for good reasons:
- It comes in 5-inch and 6-inch sizes, and the 6-inch size holds more water.
- It's usually made as one-piece gutters, rolled out of a coil of aluminum by a machine parked in your driveway, so the only joints are at the corners.
- The front reads like trim, so it fits a ranch as well as a two-story.
- Parts are easy to find, which keeps a repair down the road simple.
Where half-round makes sense
Half-round suits houses with some age on them: a brick bungalow, an old Victorian, a stone cottage, a farmhouse with a metal roof. It looks right on those in a way K-style doesn't. It's often made in copper, which goes brown and then green over the years, or in aluminum painted to match the trim.
The round bottom has one real advantage. There are no inside corners for wet leaves to pack into, so it tends to flush out a little easier in a hard rain. You pay for the look, though. Half-round usually costs more, and it comes in sections instead of one long run.
5-inch or 6-inch?
A 5-inch K-style is sold as the standard residential size. A 6-inch holds more water and calls for bigger downspouts, and the downspouts matter as much as the gutter, because a gutter can only empty as fast as its downspouts let water out.
Here's why size matters here. Knoxville averages 51.93 inches of rain a year, going by the 1991 to 2020 normals posted by the National Weather Service in Morristown. The same page lists the city's wettest day on record at 6.14 inches, on July 16, 1917. Plenty of our rain comes in summer thunderstorms that dump water hard and fast, and a gutter has to keep up with the hardest stretch of a storm, not the average day.
I'd go 6-inch when:
- The roof is steep. Water comes off a steep slope faster, which the 6-inch product page above names as a reason to size up.
- A big stretch of roof drains into one run, like the back of a two-story with a long, unbroken slope.
- Two slopes meet in a valley that dumps onto one spot of the gutter.
- Your current gutters overflow in a hard rain even when they're clean.
On a small ranch with an ordinary pitch and short runs, 5-inch is often fine, and the 5-inch product page pitches it for exactly that kind of house. That's a call to make standing in your yard looking at the roof, not from a chart.
Don't forget the downspouts
People pick the gutter and forget the downspouts, which is backwards. A gutter that overflows at one corner often has a downspout problem: too few of them, or one clogged at the bottom elbow. Adding a downspout, or moving one closer to where a valley pours in, can fix an overflow without replacing anything else. If one of yours backs up, here's how to clear a clogged downspout.
Where the water goes after that matters too. Run it away from the foundation with an extension or into a clear drain line, not into a flower bed against the wall.
Material, briefly
Aluminum is what most K-style gutters are made of, and it's what I'd put on most houses. It doesn't rust, and it comes in plenty of colors. Vinyl is cheap and easy to find at a big-box store, but it gets brittle and sags with age. The gutter lines we carry are on the products page, and how long gutters last covers how each material holds up.
How to decide
If your house is a typical ranch or two-story, get K-style. Pick 6-inch if any of the four conditions above fit, and make sure the downspouts get sized up along with it. If you've got an older house with real character, or copper already on the roof, half-round is worth the extra money. The gutters page shows what we install and how we hang it.
Questions
Can I go from 5-inch to 6-inch without replacing the fascia?
Usually, if the fascia board is sound. A 6-inch gutter takes its own hangers and bigger downspouts, per the 6-inch product page, and any soft or rotted fascia should be replaced before the gutter goes back up.
Do half-round gutters clog more than K-style?
Not usually. The round bottom has no inside corners, so debris tends to wash out. Under heavy pine needles, any gutter clogs without a guard or regular cleaning.
