Gutter Size Calculator
SEQ summer storms push domestic gutters hard. This tool estimates runoff flow from catchment area and rainfall intensity, then suggests a gutter class and downpipe count (indicative only).
Results
- Estimated peak flow
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- Suggested gutter
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- Downpipes
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- Spacing hint
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Not a hydraulic design certificate. Box gutters and large catchments need engineering. Default 150 mm/h is a planning figure — local design rainfall may differ.
Overflowing gutters often mean undersized profiles, blocked outlets or poor falls — not just “more downpipes”. See gutters & box gutters.
SEQ tips
- Coastal debris and leaf litter reduce real-world capacity — plan maintenance
- Box gutters over living areas need correct sumps, overflows and freeboard
- Match downpipe discharge to stormwater, not over footings
Planning a roof in Brisbane or on the Coast?
Use the calculators for ballparks, then get a site measure for materials that fit your home.
Call 0411 510 699