Most Pittsburgh homes with a roof under about 2,000 square feet of surface and a normal pitch do fine with 5 inch K style gutters, while homes with steep roofs, large roof planes, long straight runs, or a history of overflow should go with 6 inch gutters, which carry roughly 40 percent more water for about $2 to $4 more per linear foot. If you have ever watched water sheet over the front edge of your gutter during a summer thunderstorm in Westmoreland County, you already have your answer. Here is how we size gutters at Bella Construction, and how to think it through for your own house.
Last updated September 2026.
What is the actual difference between 5 inch and 6 inch gutters?
The number is the width across the top of the trough. A 5 inch K style gutter holds about 1.2 gallons per foot. A 6 inch K style holds about 2 gallons per foot. That sounds like a small step up, but the math on capacity is not linear. The wider trough also sits farther out from the fascia, so it catches water that is shooting off a steep roof at speed instead of letting it overshoot the lip.
There is a second difference people forget. Six inch gutters are almost always paired with 3×4 inch downspouts instead of the 2×3 downspouts that come standard on 5 inch systems. A 3×4 downspout moves nearly twice the water of a 2×3 and clogs far less often, which matters a lot in October when the oaks and maples in Irwin and North Huntingdon drop everything at once.
How much water does a Pittsburgh roof actually shed?
More than most people think. A one inch rainfall on a 1,000 square foot roof section produces about 620 gallons of runoff. Greater Pittsburgh averages close to 40 inches of rain a year, and our summer and early fall storms often dump an inch in under an hour. Add lake effect wind pushing rain sideways off the roof, and a gutter that is technically big enough on paper can still overflow at the corners and at the low end of a long run.
That overflow lands at the foundation, soaks into basements, rots fascia and rafter ends, and stains siding. The U.S. Department of Energy explains why keeping water away from the foundation matters so much for moisture control in a home. Gutter size is the front line of that fight.
When does a house need 6 inch gutters?
Roof pitch is the first thing we look at. Water coming off a 10/12 or steeper roof is moving fast, and it tends to jump a 5 inch trough entirely. Many of the older two story homes in Greensburg and the South Hills have exactly this kind of pitch, and we upgrade a lot of them to 6 inch even though the roof area alone would not call for it.
Roof area is the second factor. Once a single gutter run is draining more than about 1,000 square feet of roof, or once a run stretches past 35 to 40 feet with a single downspout, we recommend 6 inch. Big single plane roofs on newer homes in Murrysville and Monroeville often fall in this category. So do additions where two roof sections dump into one valley and then into one gutter.
Metal roofs and tile roofs shed water faster than asphalt shingles and almost always get 6 inch gutters. And if you are adding gutter guards, a 6 inch gutter gives the guard a wider opening and a better angle to shed leaves, which is one reason we pair them so often. You can read more about that on our gutter guards page.
When are 5 inch gutters the right choice?
Plenty of the time. A ranch or split level in Norwin with a 4/12 or 6/12 pitch, roof sections under 800 square feet each, and a downspout every 30 feet or so will be well served by 5 inch gutters for decades. Five inch also sits a little tighter to the fascia and looks proportionate on a lower single story house, where 6 inch can look heavy. If your current 5 inch gutters have never overflowed in a hard rain and your downspouts are placed well, there is no reason to upsize just because it is available.
Bella’s rule of thumb for gutter size
In our Westmoreland County jobs, about one in three homes we regutter ends up with 6 inch, and nearly every one of those homeowners came to us because of overflow, not because they were shopping for a bigger gutter. Our rule of thumb after 30 years: if the roof is steeper than 8/12, if any single run drains more than 1,000 square feet, or if you have seen water go over the edge even once, go 6 inch with 3×4 downspouts. Otherwise 5 inch with 2×3 downspouts, placed no more than 35 feet apart, is the right call.
5 inch vs 6 inch gutters comparison
| Factor | 5 Inch K Style | 6 Inch K Style |
|---|---|---|
| Capacity per foot | About 1.2 gallons | About 2 gallons |
| Standard downspout | 2×3 inch | 3×4 inch |
| Downspout flow | Baseline | Nearly double |
| Best roof pitch | Up to about 8/12 | 8/12 and steeper |
| Roof area per run | Under 1,000 sq ft | 1,000 sq ft and up |
| Clog resistance | Good | Better, wider opening |
| Installed cost per foot | $9 to $14 | $11 to $18 |
| Typical home total | $1,600 to $3,200 | $2,100 to $4,200 |
| Look | Trim, suits one story homes | Substantial, suits two story and steep roofs |
How much more do 6 inch gutters cost?
Seamless aluminum 5 inch gutters installed run about $9 to $14 per linear foot in the greater Pittsburgh area right now. Six inch runs about $11 to $18 per foot. On a typical 180 foot house, that works out to roughly $400 to $700 more for the larger size, including the bigger downspouts.
What moves the price is not just the width. Two story homes cost more per foot than ranches because of ladder and staging time. Fascia repair adds cost if the old gutters were leaking behind the board for years. Heavier gauge aluminum, copper, and half round profiles cost more than standard K style. Number of corners, downspouts, and the length of downspout extensions all add up. If you are doing a roof at the same time, bundling the gutters into the roofing job usually saves money, and you can see what roofing runs in our roof replacement cost guide.
Does gutter size affect how gutters look?
Yes. Six inch gutters have a noticeably taller face. On a two story colonial with a wide fascia board, that looks better and more finished. On a low ranch with a narrow fascia, 6 inch can look oversized. We bring samples of both to the estimate so you can hold them against the house. Both sizes come in the same baked on colors, so trim matching is not a factor.
Why fall is the time to decide
Gutters do their hardest work between October and March here. Leaf drop clogs undersized downspouts, then freeze thaw cycles fill an overflowing gutter with ice, which pulls hangers loose and feeds ice dams at the eaves. Getting the right size installed before the first hard freeze means the system is clear when the snow melt comes. Our fall gutter schedule usually fills by mid October.
Frequently Asked Questions
Are 6 inch gutters worth the extra money?
For a steep roof, a large roof, or any house that has overflowed, yes. The upgrade usually costs $400 to $700 on a typical home and can prevent thousands of dollars in foundation, basement, and fascia damage. For a modest ranch with a gentle pitch, 5 inch gutters are fine and the extra money is better spent on gutter guards or proper downspout extensions.
Can I put 6 inch gutters on a house that has 5 inch now?
Yes. The hangers, end caps, and outlets are all different, so it is a full replacement rather than a swap, but it does not require any change to your fascia or roof. We do this upgrade often on older homes in Irwin and Greensburg where the original builder undersized the gutters.
Do I need 3×4 downspouts with 6 inch gutters?
We strongly recommend it. A 6 inch gutter feeding a 2×3 downspout is like a wide funnel with a pinched neck. The 3×4 downspout moves nearly twice the water and is far less likely to clog with leaves and shingle grit, which matters a lot during a Western PA fall.
How do I know if my current gutters are too small?
Watch them in a heavy rain. Water sheeting over the front lip, especially at corners or at the far end from a downspout, means the gutter is undersized, has too few downspouts, or is clogged. Wet stripes on the siding under the gutter, erosion in the mulch below, or a damp basement wall after storms are the same warning in slower form.
If you are not sure which size your house needs, we will come out, measure the roof, check the pitch and the downspout spacing, and give you a straight recommendation at no charge. Fall gutter schedules are filling now, so call Bella Construction at (724) 515 5163 or visit our seamless gutters page to request a free estimate. We have been sizing gutters for Pittsburgh roofs since 1995, financing is available, and you can read what your neighbors say about the work on our reviews page.