Overflowing gutters are one of the most common roofing complaints in a wet region — and one of the most damaging, because the water ends up running down your walls instead of away from the house. The good news is the causes are usually simple and fixable.
Why gutters overflow
- Blockages — leaves, moss and debris are the number-one cause, especially under trees.
- Undersized gutters or downpipes — can’t carry the flow off a large or steep roof in heavy rain.
- Wrong fall or sagging — gutters that no longer slope to the downpipe pond and spill over.
- Damaged joints and brackets — leaking or dropped sections overflow at the fault.
Why it matters
Water spilling over the gutter runs down the wall face, soaking masonry and causing internal damp, rotting fascias and soffits, and — over time — undermining the ground at the base of the wall. What looks like a minor overflow is often the hidden cause of a damp wall inside.
Persistent overflow means damp walls.
If a gutter overflows every time it rains hard, deal with it — the water is going somewhere, usually into the wall.
Preventing overflow
- Clear gutters and downpipes at least twice a year
- Check the fall runs toward the downpipe
- Re-secure sagging sections and brackets
- Consider larger downpipes on big or steep roofs
- Related reading: how often to clean your gutters, how rainfall affects your roof, and dealing with a roof leak.
- Gutters overflowing? Find a local NFRC member roofer.
Frequently Asked Questions
Twice a year suits most homes — spring and after autumn leaf fall — and more often if you’re under trees. Our gutter cleaning guide has the detail.
Sources & Methodology
- Roof Helpline editorial standards — How we research and review roofing guidance.
