Gutter Sizing Guide, Northeast Florida
5-Inch vs 6-Inch Gutters: Why We Do Not Install 5-Inch in Florida
A 5-inch K-style gutter carries about 11 gallons per minute. A 2,000 square foot Jacksonville roof sheds about 12 gallons per minute at the peak of a summer storm. That one-gallon gap is why 5-inch gutters overflow at the corners, run water behind the fascia and cut trenches in the mulch all over Northeast Florida. Gutter Pro installs 6-inch, 7-inch and 8-inch seamless aluminum only, and owner Albert Urbank sizes every home on site before anything is quoted.
The short answer: 6-inch gutters are the right choice for Florida homes and 5-inch gutters are not. A 6-inch K-style carries roughly 45 percent more water than a 5-inch (about 16 gallons per minute against 11), pairs with 3x4 downspouts that have double the outlet area of the 2x3 downspouts sold with 5-inch, and leaves margin for the 9 inch per hour rain bursts Jacksonville sees in August and September. The material difference per foot is small. The difference in what happens to your foundation during a tropical downpour is not. Gutter Pro does not install 5-inch on any home in Northeast Florida; a 6-inch seamless system runs $9 per linear foot installed.
5-Inch vs 6-Inch Gutters at a Glance
| Spec | 5-Inch K-Style | 6-Inch K-Style |
|---|---|---|
| Capacity (gallons per minute) | About 11 GPM | About 16 GPM, roughly 45 percent more |
| Standard downspout | 2x3 (6 square inches of outlet) | 3x4 (12 square inches of outlet) |
| Jacksonville roof it can handle at 9 in/hr peak rain | Under about 1,800 sq ft of roof, no margin | Up to about 3,000 sq ft of roof with 3x4 downspouts |
| Where it is common | Builder default in lower-rainfall states and on Florida production homes | Gutter Pro standard for most Northeast Florida homes |
| Debris handling (live oak, pine, Spanish moss) | Narrow trough clogs and overflows fast | Wider trough; the size LeafBlaster Pro and Alu-Rex DoublePro guards are installed on |
| Fascia coverage | Shallower, less of the fascia board protected | Deeper profile, covers more fascia, more room for a proper pitch to the outlet |
| Gutter Pro installed price | Not offered | $9 per linear foot, 0.032 seamless aluminum, hidden hangers every 24 inches |
| Step up when | Always, in Florida | Metal or tile roof, steep pitch, long roof planes or 3,000+ sq ft: see 6 vs 7 vs 8 inch |
Capacity figures are the same ones used in our Florida gutter pricing report. Roof-size limits assume a standard 5/12 pitch at Jacksonville's 9 inch per hour peak rate; tile, metal and steep roofs shed faster and need the next size up.
Why 5-Inch Gutters Overflow in Jacksonville
Nothing is wrong with a 5-inch gutter in Ohio. It was sized for moderate, steady rain. Northeast Florida gets about 53 inches of rain a year, and most of it arrives in short, violent bursts between June and October, with the heaviest events in August and September. A gutter is rated by how much water it can move in one minute, and a Florida storm is a one-minute problem repeated for an hour.
The math on a 2,000 square foot roof
A 2,000 square foot roof at a standard 5/12 pitch, under a 9 inch per hour peak rate, produces about 12 gallons per minute of runoff. A 5-inch K-style carries about 11. The gutter is full before the storm peaks, and everything after that goes over the front lip. A 6-inch carries about 16, which is the margin that keeps the water in the trough through the worst ten minutes of the storm.
The downspout is the real bottleneck
A gutter can only drain as fast as its outlets. 5-inch systems are almost always hung with 2x3 downspouts, which have 6 square inches of opening. The 3x4 downspouts we install with 6-inch have 12 square inches, double the outlet. In a downpour the 2x3 backs up first, the water stacks at the outlet end of the run, and the gutter overflows there even if the run itself was wide enough. That is why the overflow on a 5-inch house is usually at one corner.
Live oak, pine and Spanish moss
A narrow trough clogs faster. Oak tassels in spring and pine needles year-round build a mat in a 5-inch gutter that a 6-inch takes months longer to accumulate, and a 6-inch is the width that LeafBlaster Pro micromesh and Alu-Rex DoublePro guards are built to sit on properly.
Roof pitch and roof material multiply the flow
Steep architectural pitches, standing-seam metal and barrel tile shed water faster than asphalt shingle on a moderate pitch. Two homes with the same square footage can need different gutter sizes on pitch and material alone. That is also why some homes in Nocatee, Ponte Vedra and the coastal communities move past 6-inch to 7-inch gutters with 4x5 downspouts.
Where the overflow ends up
Water that clears the gutter lands at the drip line, 12 to 18 inches from the slab. On Northeast Florida sand and clay it cuts a trench, washes out the mulch bed, saturates the soil along the footing and, on a two-story home, drives water into the soffit and behind the fascia. Most of the drainage work we do starts with a gutter that could not keep up.
What 6-Inch Gives You That 5-Inch Cannot
- About 45 percent more capacity. 16 GPM against 11 GPM is the difference between margin and overflow on an ordinary Jacksonville roof.
- 3x4 downspouts. Twice the outlet area of a 2x3, so the run drains as fast as it fills. We place downspouts by roof plane, not by what looks tidy from the street.
- Room for a real pitch. A deeper trough lets the gutter fall properly toward each outlet without the back edge dropping below the drip line.
- More fascia covered. The taller back of a 6-inch profile shields more of the fascia board from wind-driven rain.
- Guards that fit. LeafBlaster Pro 316 stainless micromesh fits 6, 7 and 8-inch, and the Alu-Rex DoublePro continuous hanger is a 6-inch product (it is also made in 5-inch, which we do not install; 7-inch takes the Alu-Rex single-layer continuous hanger). Guards on a 5-inch gutter protect a trough that was already too small.
- Seamless 0.032 aluminum, formed on site. One continuous run per roof edge, no mid-run seams, hidden hangers at 24-inch maximum spacing. Sectional 5-inch from a home center leaks at every joint within a few seasons.
Should You Replace 5-Inch Gutters with 6-Inch?
Replace them when they are failing, not because of the number on the profile. Signs that a 5-inch system has already lost the argument with Florida rain:
- Water sheets over the front edge at one or two corners during a hard rain.
- A trench or washed-out mulch line directly under a gutter run.
- Staining, peeling paint or soft wood on the fascia behind the gutter.
- Downspouts that spit from the top elbow in a storm (a 2x3 that cannot keep up).
- Sectional joints dripping between storms, or hangers pulling out of the fascia.
- A two-story home, a metal or tile roof, or a roof over about 1,800 square feet carrying 5-inch at all.
If a small single-story home has 5-inch gutters that do not overflow and the fascia is dry, there is no emergency. The sensible time to move to 6-inch is when the roof is replaced, when guards are added, or when the first of the signs above shows up. Our guide to gutter repair vs replacement covers the rest of that decision, and coordinating gutters with a roof replacement is the cheapest sequence when both are due.
Find out what size your roof actually needs
Albert Urbank measures roof area, pitch and downspout count on site, free, and the written itemized quote is the price the job is installed at.
Get a Free QuoteWhat a 6-Inch Seamless System Costs in Jacksonville
A 6-inch K-style seamless aluminum system from Gutter Pro is $9 per linear foot installed, plus $110 per first-story downspout. A 1,200 to 1,600 square foot single-story home with 120 to 160 feet of gutter and four downspouts lands at about $1,520 to $1,880; a 2,400 to 2,800 square foot home with 190 to 240 feet and six or seven downspouts at about $2,370 to $2,930. Second-story runs add $1 per foot and $220 per downspout. LeafBlaster Pro micromesh guards add $12 per foot and Alu-Rex DoublePro $14 per foot.
Every figure above comes from the Florida gutter pricing report, which lists real installed jobs by neighborhood and a cost-by-house-size table, or run the free Jacksonville gutter cost calculator for your footprint. New installs carry our lifetime workmanship warranty.
How We Size a Home on Site
On-Site Assessment with Owner Albert
Albert walks the roof edge, checks the fascia and looks at where the existing gutters have been overflowing. Stain lines, washed mulch and soft fascia tell the story before a tape measure comes out.
Roof Area, Pitch and Material
Each roof plane is measured and its pitch and surface noted. Shingle at 5/12 and metal at 8/12 drain the same square footage very differently, and the size follows the plane that sheds the most water, not the average.
Downspout Count and Placement
Outlets are placed by roof plane and valley, sized 3x4 on 6-inch and 4x5 on 7-inch and 8-inch, and routed to discharge away from the slab or into underground drainage where the yard needs it.
On-Site Fabrication and Install
The roll-forming machine comes to the house. 0.032 aluminum is formed into one continuous run per roof edge, hung on hidden hangers at 24-inch maximum spacing, with sealed miters at the corners. Our in-house crew does the work; nothing is subcontracted.
Flood Test and Walkthrough
Every run is water-tested from the roof before the crew leaves, and you get the walkthrough. If a 5-inch system comes off, it goes with us.
Where 5-Inch Gutters Show Up Across Northeast Florida
St. Johns County production communities
Nocatee, Julington Creek, Durbin Crossing and the newer phases along County Road 210 were largely delivered with builder-grade 5-inch sectional gutters. Lots are tight, so one overflowing corner sends water onto the neighbor's slab. See our St. Johns, Nocatee and Julington Creek pages.
Clay County and the Westside
Fleming Island and Orange Park homes from the 1990s and 2000s commonly carry original 5-inch runs under heavy pine and oak canopy, the worst combination for a narrow trough.
Coastal and Intracoastal
Salt air, wind-driven rain and standing-seam metal roofs push Jacksonville Beach and Ponte Vedra homes straight past 5-inch, and often past 6-inch to 7-inch with marine-grade fasteners.
Mandarin, San Marco and the older Jacksonville neighborhoods
Large oaks and long single-story roof lines in Mandarin and the historic core mean heavy debris and long runs to each outlet. 6-inch with correctly placed 3x4 downspouts is the floor, and Jacksonville homes under full canopy usually add guards at the same time.
5-Inch vs 6-Inch Gutters FAQ
Are 5-inch gutters big enough for a house in Florida?
Not reliably. A 5-inch K-style carries about 11 gallons per minute, and a 2,000 square foot roof at a standard pitch produces about 12 gallons per minute at Jacksonville's 9 inch per hour peak rain rate. The gutter is full before the storm peaks. 6-inch, at about 16 gallons per minute, is the minimum we install on any Northeast Florida home, and larger or steeper roofs move to 7-inch.
How much more water does a 6-inch gutter hold than a 5-inch?
About 45 percent more by flow: roughly 16 gallons per minute against 11. The bigger gain is at the outlet, because 6-inch pairs with 3x4 downspouts that have 12 square inches of opening, double the 6 square inches of the 2x3 downspouts usually hung with 5-inch. Capacity and outlet together are why a 6-inch system keeps up in a tropical downpour and a 5-inch does not.
Is it worth upgrading from 5-inch to 6-inch gutters?
Yes when the 5-inch system overflows, the fascia is staining or soft, there is a trench under the drip line, or the home is two stories or has a metal or tile roof. A 6-inch seamless system from Gutter Pro is $9 per foot installed, typically $1,500 to $2,900 for a 1,200 to 2,800 square foot home, with a lifetime workmanship warranty. A small single-story home whose 5-inch gutters do not overflow can wait until roof or guard work is due.
Can I put gutter guards on 5-inch gutters?
You can, but you are protecting a trough that is already too small for Florida rain, and a guard slows the water slightly at the edge, which a 5-inch has no margin to absorb. Alu-Rex DoublePro is made for 5-inch and 6-inch, but we only install it on 6-inch because we do not install 5-inch at all; LeafBlaster Pro fits 6, 7 and 8-inch. If guards are the goal, the right order is 6-inch seamless first, then guards on the same visit.
What size downspouts go with 6-inch gutters?
3x4 rectangular downspouts are standard on 6-inch. They move twice the water of the 2x3 downspouts sold with 5-inch systems. 7-inch and 8-inch gutters step up to 4x5 downspouts. We size the outlet to the roof plane feeding it, and we do not install 2x3 downspouts on any system.
Why do Florida builders install 5-inch gutters?
Cost and habit. 5-inch is the national default and the cheapest profile to buy and hang, so production builders specify it across every phase of a community regardless of roof size, pitch or canopy. Nothing in the sales process checks it against the roof. It fails the first August storm instead, which is why so many homes in St. Johns and Clay County replace builder gutters within the first few years.
Does a 6-inch gutter look too big on a one-story house?
No. The extra inch sits against the fascia, and on most Jacksonville homes the 6-inch profile actually looks more proportional because it covers more of the fascia board. K-style 6-inch is the most common profile on new custom homes in the area. If a different look matters, half-round and box profiles are available in 6-inch and larger too; see our guide to K-style vs half-round vs box gutters.
Quick Answers
Still on 5-inch?
Roof area, pitch and downspout count decide what your home needs, and that takes a tape measure, not a guess. Albert Urbank sizes it on site, free, and the written itemized quote is the price the job is installed at.
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