Sizing, not sales
5-Inch vs. 6-Inch Gutters in Chattanooga: Which Does Your Roof Need?
The right trough is a math problem: design area equals actual roof area times a pitch factor. Hamilton County rain and clay soil punish an undersized 5-inch leftover from the builder.
A 5-inch K-style seamless run handles about 5,500 square feet of roof when it is paired with 2x3 downspouts and pitched 1/4 inch per 10 feet toward the outlet. A 6-inch K-style run handles about 7,900 square feet and wants oversized 3x4 downspouts. That is roughly 40 percent more water moving off the fascia in a Tennessee Valley cell—not a cosmetic upgrade.
Pitch factors matter as much as footprint. Flat to 3/12 uses 1.0. A 4/12 to 5/12 roof uses 1.05. Six-twelve to 8/12 uses 1.10. Nine-twelve to 11/12 uses 1.20. A 12/12 or steeper roof uses 1.30. Multiply the actual squares by that number before you decide 5-inch is “fine because the neighbor has it.”
Where 5-inch still belongs
Modest one-story footprints, moderate pitch, and a clear shot to two or more 2x3 outlets can live on 5-inch .027 aluminum. We still roll-form it on-site so there is no joint every 10 feet, and we still hang hidden screw hangers 24–30 inches into rafter tails. 5-inch is not junk. It is just the wrong call when the roof is steep, metal, or large.
Ooltewah and East Brainerd new construction often ships with builder 5-inch sectional systems on roofs that design out well above 5,500 square feet. The first spring storm overflows at the corners. That is not a cleaning problem. That is a trough that was never sized.
When we hang 6-inch
Steep pitches, standing-seam or metal roofs, multi-story lakefront homes in Hixson, and anything on Signal Mountain or Lookout Mountain grade usually get 6-inch .027 or .032 with 3x4 downspouts. .032 is the heavy-gauge residential and light-commercial coil. We inspect fascia first. A 6-inch trough on rotten wood is still a callback.
Downspout count is part of the same decision. A 3x4 outlet moves about twice the water of a 2x3 at the same head. If we hang 6-inch and leave the original 2x3, we have only moved the bottleneck to the elbow. See downspout and drainage work when the outlet is the weak link.
What changes the price
Linear footage, stories, color, downspout count, and fascia condition. We do not quote 6-inch from a photo. We measure, probe the board, and write an estimate you can take 30 days to consider. Pairing 316 stainless micro-mesh at install is the cheapest time to add protection for oak and pine debris.
The capacity table also lives on our seamless gutter installation page. If you want the same math applied to a steep or metal roof, read how we size gutters for steep and metal roofs.