Gutters · South Miami
Gutters in South Miami, FL
In South Miami, a 10-year storm can drop rain at 11 inches an hour for five minutes. That is far harder than most gutters were sized to handle. Gutters here need to be sized for short, intense bursts, not just the total rain in a day. Miami-Dade's housing stock is also older, with a median build year of 1969 for the city, so many existing gutters may be original.
Updated October 2026
Our workSizing for the storm
How much rain your gutters need to carry in South Miami
Rain at this site is measured in bursts as well as totals. A 1-hour rain in a 10-year storm falls at 3.36 inches an hour, and a 100-year storm at 5.18. The 5-minute rate is the number that matters most for gutter flow, because it arrives all at once. Most of the water in a short, heavy burst has to leave through the gutter and downspout before it can overflow.
IllustrationIllustration: micro mesh guard
Over a full day, a 10-year storm here delivers 8.43 inches, and a 100-year storm delivers 14.8 inches. Those totals matter for drainage around the lot, but the short burst is what overwhelms a small gutter. By our arithmetic, a 10-year rain of 8.43 inches spread across the day still has short bursts that can overflow a narrow channel.
The plumbing code sizes horizontal gutters from the flow off the roof, so a larger roof needs a larger channel. At Miami International Airport the 1991 to 2020 normal is 67.41 inches a year, so the flow off a Miami-Dade roof is heavy in the wet months. Moving up one size adds about 49 percent more capacity at the same slope. For a larger roof or a steep pitch, that jump is often the difference between a gutter that holds and one that spills.
Code rules for discharge
Where downspouts must send the water
Florida's building code asks for gutters where eaves stick out less than 6 inches, which is common on older Miami-Dade ranch homes built around a 1969 median. Gable end rakes and a roof built over a lower roof are left out of that rule. The same section sets how far each downspout must carry water from the sidewall, and says how that run can be built.
Downspout capacity is also set by size. A 4-inch round leader carries 192 gallons per minute, a 5-inch round leader carries 360, and a 2-by-2-inch leader carries only 30. A gutter sized correctly but drained through a small downspout still backs up at the corner. Confirm the leader size with the building office before a replacement.
Trees and upkeep
Leaves, pollen and cleaning on South Miami lots
Southern live oaks are semi-evergreen and drop fruit and leaves as a litter problem, and they can reach 60 to 80 feet tall. Oaks, pines and melaleucas are among the major pollen producers in Florida. The pollen season runs from January to June, peaking in March and April. Those drops end up in gutters and screens.
- Clear them once the spring oak leaf drop finishes, around late April to May.
- Before storm season runs from June through September, make sure they are cleared out once more.
- Clear them a third time when the autumn pine needles stop falling, late in the year.
Clean at least twice a year and more often under heavy canopy, since clogged gutters can cause water damage, mold and foundation problems. Gutter screens help less than many expect: Consumer Reports found even the top-scoring screen was only middling at containing a severe downpour. Climbing a ladder is still needed.
Rain on your roof
Preset: 8.43 inches, the 10-year 24-hour rain (NOAA Atlas 14 at South Miami).
10,504 gallons run off that roof, all of it toward the gutters and downspouts.
Math: square feet × inches × 0.623 gallons.
Questions
Gutters in South Miami: questions
How hard does it rain in South Miami?
A 10-year storm here drops rain at 11 inches an hour over five minutes, and at 3.36 inches an hour over one hour. A 24-hour 10-year storm delivers 8.43 inches. These are NOAA Atlas 14 design values for this town, so a gutter should be checked against the short burst, not only the daily total. The building office can confirm the design basis used for your permit.
Source: NOAA Atlas 14 Volume 9 version 2, partial-duration intensity estimates at the South Miami 2020 Census internal point (25.7085, -80.2951), read Oct 5, 2026
Where do my downspouts have to drain?
The Florida residential code says downspouts must discharge at least 1 foot from the building's sidewall, using underground piping, tail extensions or splash blocks. The rule applies to gutters on buildings with eaves under 6 inches. In South Miami, where a 10-year storm drops 8.43 inches in a day, water that lands near the foundation is the most common cause of wall and slab trouble.
Source: 2023 Florida Building Code, Residential, 8th ed., R318.5 (UpCodes viewer, unofficial transcription); FBC-Building 1503.7, read Oct 5, 2026
How often should I clean gutters with trees around my home?
Experts cited by a Florida home insurer recommend cleaning gutters at least twice a year, in spring and fall, and more often with overhanging trees. In South Miami the pollen season runs January to June and peaks in March and April. Under oaks and pines, plan a cleaning after the spring leaf drop, before June, and after the autumn pine-needle peak.
Source: thig.com, read Oct 5, 2026
Are gutters required on South Miami homes?
The Florida code calls for gutters with downspouts where eaves project under 6 inches, with exceptions for gable end rakes and a roof above another roof. Wider eaves fall outside that rule. Check your eave width and any permit with the City of South Miami Building Division before work starts. A 2026 check of its page found the permit information verified.
Source: 2023 Florida Building Code, Residential, 8th ed., R318.5 (UpCodes viewer, unofficial transcription); FBC-Building 1503.7, read Oct 5, 2026
Sources for this page(28)
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- 3.U.S. Census Bureau, American Community Survey 2024 5-year estimates (2020-2024), table B25035, via Census Reporter API. Read Oct 5, 2026.
- 4.Median year homes were built: 1969. U.S. Census Bureau, American Community Survey 2024 5-year estimates (2020-2024), table B25035, via Census Reporter API. Read Oct 5, 2026.
- 5.Permit office: City of South Miami - Building Division. City of South Miami - Building Division. Read Oct 10, 2026.
- 6.2023 Florida Building Code, Plumbing, 8th ed., Chapter 11 (UpCodes viewer, unofficial transcription). Read Oct 5, 2026. FBC text read from UpCodes (unofficial transcription): check floridabuilding.org or the ICC viewer before quoting (spec 8.7). Source URL inherited from COM-20 (the research cites it "as COM-20").
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- 16.NOAA Atlas 14 Volume 9 version 2, partial-duration intensity estimates at the South Miami 2020 Census internal point (25.7085, -80.2951), NOAA Hydrometeorological Design Studies Center. Read Oct 5, 2026.
- 17.NOAA Atlas 14 Volume 9 version 2, partial-duration 24-hour depth estimates at the South Miami 2020 Census internal point (25.7085, -80.2951), NOAA Hydrometeorological Design Studies Center. Read Oct 5, 2026.
- 18.City of South Miami - Building Division, City of South Miami. Read Oct 5, 2026.
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- 28.NOAA Atlas 14 at South Miami: 11 in/hr (5-minute, 10-year). NOAA Atlas 14 Precipitation Frequency Data Server. Read Oct 5, 2026.
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Gutters in South Miami
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