Fine Homebuilding Project Guides

Roofing

How-To

How to Hang Half-Round Gutters

This classic look is made even better with modern materials, but getting the installation details right is key for functional and good-looking gutters.

By Andrew Grace Issue 274 - April/May 2018

Synopsis: Remodeler Andrew Grace walks through the process of hanging half-round gutters, from locating the hangers in the right spots depending on the roof pitch, to hanging and joining the sections, to laying out and connecting the downspouts. Detailed drawings give tips for proper hanger and downspout layout.

It’s tough to improve upon the timeless look of half-round gutters. They were a natural fit for a 1919 farmhouse and garage we recently worked on. Although half-round gutters are also available in galvanized steel (least expensive) and copper (most expensive), my client chose aluminum, which is rust-free and more reasonably priced than copper. The 0.032-in.-thick aluminum gutters on the project are 6 in. wide with a durable, factory-applied finish.

Installing half-round gutters is a little more complicated than installing more conventional K-style gutters because the hangers are visible, so they must be evenly spaced and perfectly straight or the finished product will look terrible. This article, which covers an entire gutter and downspout installation, focuses on the tips and tricks that make the process faster and easier.

The first thing to keep in mind when you’re planning a gutter project is that a 5-in. half-round gutter can handle about half as much water as a 5-in. K-style gutter, so you need more downspouts or a larger gutter, and sometimes both. Proper sizing takes into account the roof dimensions and slope, as well as the heaviest rainfall you can expect for the project location. The gutter manufacturer we used, Berger Building Products, has helpful sizing information for both gutters and downspouts on their website (bergerbp.com). Labor and materials for this project came in at about $10 per ft.

Get the hangers in the right spot

The manufacturer recommends that the gutter hangers be installed at a maximum of 36 in. on center to provide adequate support. In colder climates, where snow and ice could accumulate, they should be closer together. This building’s sloped fascia required adjustable hangers to hold the gutter in the right position, but hangers for straight fascia and exposed rafter tails are also available.

Roof slope guides mounting height

Plumb fascia

Half-round gutter hangers should be mounted so that the gutter sits below the extended roofline, allowing snow and ice to slide over the gutter without getting caught. The distance below the extended roofline depends on the roof slope, with steeper roofs requiring less clearance than roofs with a lower slope.

Angled fascia

Mounting half-round gutters to an angled fascia follows the same clearance rules, but requires an adjustable hanger with an extended shank. Adjustments are made through trial and error, until the gutter sits level front to back. Once the adjustments on the first hanger are finalized, additional hangers
are assembled.

Proper layout

Hang and join the sections

It’s impossible to fasten the hangers when the gutter is in place, so all the hangers must be mounted on the fascia before setting the 10-ft. sections of half-round gutter. Aluminum half-round gutter sections are joined with slip-joint connectors, aluminum gutter cement, and pop rivets. Steel and copper half-round gutters can be joined with slip-joint connectors or soldered.

1. First, notch the edges with aviation snips. — 1

2. Then, cut the pieces free with a miter saw using a carbide-tipped 80-tooth wood-cutting blade. — 2

3. Test-fit the pieces (If the slip connector doesn’t fit, open it slightly with a straight screwdriver), and then place a 1⁄4-in. bead of aluminized gutter cement inside the connector and slide the pieces together, ensuring they’re fully seated with a bump from your hand. — 3

Prep for joints. The straight hem at the rear of the gutter and the rolled edge at the front must be removed so the slip connector can be placed on the end of the gutter. 1 First, notch the edges with aviation snips. 2 Then, cut the pieces free with a miter saw using a carbide-tipped 80-tooth wood-cutting blade. 3 Test-fit the pieces (If the slip connector doesn’t fit, open it slightly with a straight screwdriver), and then place a 1⁄4-in. bead of aluminized gutter cement inside the connector and slide the pieces together, ensuring they’re fully seated with a bump from your hand. Wipe away any excess cement before it dries.

Join the sections. It may be tempting to join all the sections on the ground and then lay in the entire gutter section. Unfortunately, a long run of gutter is easily damaged and it’s difficult to lock the rear edge into all of the hangers when the piece is longer than 10 ft. Instead, install one side of the slip connector on the ground and join the other end with the gutter in the hangers. Connect the pieces permanently with pop rivets, drilling each pilot hole from inside the gutter to ensure the hole goes through the connector, and then pop rivet from the bottom so the color-matched rivets are less visible. — **Join the sections.** It may be tempting to join all the sections on the ground and then lay in the entire gutter section. Unfortunately, a long run of gutter is easily damaged and it’s difficult to lock the rear edge into all of the hangers when the piece is longer than 10 ft. Instead, install one side of the slip connector on the ground and join the other end with the gutter in the hangers. Connect the pieces permanently with pop rivets, drilling each pilot hole from inside the gutter to ensure the hole goes through the connector, and then pop rivet from the bottom so the color-matched rivets are less visible.

Prep for the downspouts

It’s easier to install the outlet tubes that connect the gutter to the downspouts on the ground rather than up in the air, but the most accurate way to locate the holes is by doing a test fit. If the gutters connect to an underground roof-water system, these pipes should dictate the downspout layout in order to minimize offsets and extra fittings. The process starts at the bottom.

Lay out & cut perfect holes

A scrap of gutter with the edges removed acts as a template for the oval-shaped hole for the outlet tube that joins the downspout to the gutter. Make the template by tracing the inside of the tube onto the scrap and gradually enlarging the hole with aviation snips until the perfect fit is achieved. To use the template, place it on the section of gutter and trace the hole, and drill a starter hole for the aviation snips. Follow the outside of the pencil line with the snips.

Connect the downspouts

Smooth and corrugated downspouts are available in galvanized steel, copper, and aluminum in diameters ranging from 2 in. to 7 in. There are also several types of downspout hangers with mounting options suitable for all types of wall cladding. It’s important to have enough downspouts in sufficient diameter to handle all the water expected in a heavy rainfall. Gutter manufacturer websites can help with proper sizing of both gutters and downspouts.