Half Round Gutters: Sizes, Hangers and When to Choose Them

Half round gutters (also called half round eavestrough or half round rain gutters) are shaped like a pipe cut lengthwise, with a rolled bead along the front edge. They're the traditional gutter on houses built before the 1950s and the usual choice for copper. They drain cleanly and are easy to flush out, but they hold less water than a K-style gutter of the same width, so they're usually sized up.

Sizes

Half round is sold by the width of the opening, most often 5 or 6 inches, with 7 and 8 inches for large roofs and commercial work. A common rule among installers is to go one size larger than you would with K-style. If a 5-inch K-style would do, use 6-inch half round.

Downspouts are usually round (3 or 4 inches) to match, though plain rectangular downspouts work with an adapter.

Opening	Typical downspout	Where it fits
5-inch	3-inch round	Porches, small roofs, short runs
6-inch	3- or 4-inch round	Most houses
7- or 8-inch	4-inch round or larger	Large or steep roofs, historic churches and commercial buildings

Single bead or double bead

The bead is the rolled front edge that stiffens the gutter. Single bead (front only) is standard. Double bead rolls the back edge too, and it's the more traditional European style. It makes the gutter a little stiffer and finishes the back edge where it meets the fascia, but it costs more and the hangers must be made for it. Buy hangers to match the bead type and size.

Hangers

Because half round has no flat back, it can't screw straight to the fascia like K-style. You pick from three hanger types:

• Shank hangers screw into the fascia and wrap the gutter. The most common choice.
• Fascia brackets are flat straps that mount to the face of the fascia board.
• Rafter (strap) hangers fasten to the roof deck or rafter top under the shingles. Best done during a reroof.

Space hangers about 24 to 30 inches apart in mild climates and closer in snow country. Hangers are visible on half round, so many buyers choose cast or copper hangers on purpose.

Metals

• Copper is the classic. It weathers from bright to brown to green over years and can last 50 years or more. Use only copper hangers, fasteners and downspouts with it; mixing metals causes galvanic corrosion.
• Aluminum half round is the budget option and comes painted.
• Galvalume and galvanized steel are stiffer than aluminum and cost less than copper.

Pros and cons vs. K-style

Half round	K-style
Smooth curve flushes clean; debris doesn't lodge in corners	Inside of the front lip traps debris
Holds less water per inch of width	Holds more water per inch of width
Visible hangers, period look	Hidden hangers, modern look
Usually seamed sections, more joints	Usually seamless on site
Higher price per foot	Lowest price per foot

Is half round right for your house?

Choose half round if the house is historic, if you're buying copper, or if you want a gutter that's easy to keep clean. Choose K-style if you need maximum capacity for the money or want hidden hangers. On a big, steep roof in heavy-rain country, a 6-inch K-style usually outperforms a 6-inch half round. If you're set on the half round look there, go to 7 inches and add downspouts.