In short
Gutters overflow because water cannot get away fast enough: a blockage, a gutter that has sagged or lost its fall, a joint pulling apart, or a blocked downpipe. Leaves and moss are the usual cause. If the gutter is clear and still overflows in ordinary rain, the brackets or the fall are wrong and it needs refitting.
This is a job for our Fascia, Soffit & Guttering service.
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The usual causes, in order
- Blockage. Leaves, moss off the roof, a tennis ball, a bird's nest. Checkatrade's 2026 gutter guide says plants growing out of the gutter or water spilling over the edge often means a clean is all that is needed. Around Bungay, Beccles and Harleston, where houses sit under mature trees, this is a lot of what we see.
- Lost fall. A gutter has to run downhill to the outlet. FloPlast, who make the uPVC systems we fit, set the maximum fall at 1:350. If brackets have dropped, or the fascia behind them has rotted, water pools in the low spot and spills.
- Too few brackets. FloPlast specify fascia brackets no more than a metre apart. Older installs often have them much further apart, so the gutter bows under the weight of water and ice.
- Joints letting go. uPVC moves with temperature. If a union was fitted tight against the gutter end with no room for expansion, it pulls apart and drips.
- Blocked downpipe. The gutter looks clear but water backs up from the bottom. A hopper full of leaves is the classic.
- Undersized gutter. A big roof draining to one outlet in a heavy downpour needs a deeper profile or a second downpipe.
Why it matters
Overflowing water runs down the wall, saturates the brickwork and shows up inside as blown plaster and damp patches, usually in the top corner of a bedroom. It also rots the fascia board the gutter hangs from, which is how a cheap clean turns into a roofline job. A good share of the internal plaster we repair across Norfolk started as a gutter problem outside.
What we do
We clear it first and, if we can, watch it in the rain. Then:
- Refix or replace dropped brackets and reset the fall to the outlet.
- Replace failed unions and end caps. Checkatrade's May 2026 guide puts a joint repair at roughly £60 to £90, so a leak at a union is a small job.
- Where the fascia behind has gone soft, replace the fascia and soffit and hang the new gutter on sound boards.
- Add a downpipe or step up to a deeper profile if the run is too long for one outlet.
Keeping it clear
Clear gutters once a year, twice if you have trees close by, and check the downpipe outlets at the same time. Fit a leaf guard at hoppers under trees. If your fascias are timber, look at them while you are up there: peeling paint and soft spots mean water is already getting in.