Most gutter companies install one size because that is what fits on the truck. We roll-form 5″, 6″, and 7″ — the only contractor in West Michigan offering all three — which means we can size to your roof instead of to our inventory. Here is how the decision actually works.
5″ K-Style: The Residential Standard
Correct for the large majority of homes here. Moderate roof area, normal pitch, adequate downspout locations. If your house is a typical Grand Rapids two-story or ranch and your existing 5″ gutter only overflows when it is clogged, 5″ is fine.
6″ K-Style: More Common Than You Think
A 6″ gutter carries roughly 40% more water than a 5″. Go to 6″ when:
- Large roof area draining into a single run
- Steep pitch — steeper roofs deliver water to the gutter faster, and velocity matters as much as volume
- Long uninterrupted runs with few places to put a downspout
- Metal roofing, which sheds water dramatically faster than asphalt
- Valleys dumping into a single corner — a valley can shoot water up to 10 feet past the drip edge
6″ also takes a 3×4 downspout comfortably rather than the 2×3 typical on 5″, which matters because the outlet is usually the real bottleneck.
7″ K-Style: Specialty
Commercial, industrial, agricultural, and the occasional very large residential roof. Almost nobody in Michigan carries it. If a contractor tells you your building needs fabricated box gutter, ask about 7″ seamless first — it is usually cheaper and has fewer joints.
Downspouts Are Half The System
Rule of thumb: one 3×4 downspout per roughly 1,200 square feet of roof drainage area. Take a 40-foot run on a roof 16 feet to the peak — 40 × 16 = 640 sq ft, so one 3×4 handles it. Two downspouts on an oversized gutter beat one downspout on an oversized gutter every time.
Always ask how many downspouts a quote includes. It is one of the easiest places for a low bid to hide.
The Mistake We Fix Most
Undersized gutter on a steep, large roof. It overflows in every hard Michigan downpour no matter how clean it is, and no gutter guard fixes it — guards manage debris, not capacity. If a company sells you guards to solve overflow without measuring your roof area, get another quote.
We measure roof area and pitch on every estimate and size the system to it. Free, no appointment: (616) 532-2200.
Need a hand with this? We've been on West Michigan roofs since 1988. Estimates are free and there's no obligation — call (616) 532-2200 or request one online.
