I’ve been in this business long enough to know that the gutter you choose will either save you money or cost you callbacks. It’s not about what the customer saw on YouTube, what their neighbor said, or what a builder used 15 years ago. It’s about what works, and I’ll take 6-inch K-style over 5-inch every single time.
Let’s start with capacity. A 6-inch gutter moves about 40% more water than a 5-inch. That doesn’t mean much until you see a 5-inch gutter spilling over on a steeper roof during a hard summer storm. And in North Jersey, we don’t get gentle rain. We get sideways downpours that dump two inches in twenty minutes. A small gutter on a big roof doesn’t have a chance. Especially on newer homes with wide fascia and multi-pitch roof lines—5-inch just doesn’t cut it.
But it’s not just the rain volume. It’s the roof surface area. A two-story colonial with a 12/12 pitch? You’re feeding a lot of water to that gutter, fast. Add in valleys that dump runoff into one concentrated spot, and the 5-inch system gets overwhelmed. Then you’re explaining to a customer why water is running behind the gutters or overflowing onto their patio. I’d rather install the right size once than take a phone call later and explain why the wrong size was “standard.”
And that’s another thing—“standard” doesn’t mean better. A lot of contractors still push 5-inch because it’s cheaper and they’ve always used it. That’s fine until you have to deal with the drip edge detail, or try to install leaf protection that actually works. Most of the higher-end gutter guards sit cleaner and perform better on 6-inch systems. It’s a smoother fit with the wider opening, and it handles debris better too.
We’ve retrofitted more 5-inch systems than I can count. Homeowners call when water’s damaging their fascia, soaking their basement, or freezing up their walkway. Nine out of ten times, it’s an undersized system that looked fine on paper but couldn’t keep up with reality.
And let’s not ignore the money side. Total dollar value of 6-inch system may be 7-10% higher; sometimes more; sometimes less. When a client is making a decision over a capital investment that will help protect their most valuable asset over the next 20+ years, 10% price difference should not drive decisions.
For installers, margins on 6-inch are a little better. But bigger upside comes from fewer callbacks, happier customers, more upsell potential with guards. It’s also a cleaner install when you’ve got larger crown or wider trim, which matters when you’re working on homes in towns like Montclair, Franklin Lakes, or Alpine—where curb appeal matters and the client doesn’t want flimsy aluminum looking like an afterthought.
I don’t cut corners. I don’t upsell to upsell. But when a homeowner asks why I recommend 6-inch over 5, I tell them the truth: it’s the size that works. And I’d rather do the job once and not come back than save a couple bucks and end up redoing it.