Why gutters leak at the joints
Plastic gutters are made in lengths joined by unions, corners and stop ends, each with a rubber seal. Those seals harden and shrink with age and sunlight. Plastic also expands and contracts with temperature, so on a hot day a gutter can pull slightly out of its connector and stay there. Dirt trapped in the joint stops it closing properly. The result is a steady drip at the same spot every time it rains. On cast iron gutters, the joints are bolted and sealed with putty or sealant, which dries out and cracks, and rust can eat into the overlap.
The fix is normally to clean the joint and fit a new seal or connector. If the gutter ends have been distorted, a short length may need replacing so the joint can close.
Why a gutter overflows
An overflowing gutter is usually a flow problem rather than a leak. Common causes:
- Leaves, moss or silt blocking the gutter or outlet.
- A downpipe blocked lower down, often at a bend or the swan neck.
- The gutter has lost its fall and water sits instead of running.
- A valley or a large roof slope pouring more water into one spot than the gutter can take.
- The gutter is set too low or too far out, so water shoots over it in heavy rain.
Clearing the gutter is the first step; our gutter cleaning page covers that. If it overflows when clear, the size, position or fall is likely the problem.
Sagging gutters
A gutter that dips between brackets is either carrying too much weight from debris and standing water, has brackets spaced too far apart, or is fixed to a fascia that's gone soft. Re-setting or adding brackets restores the fall. If the screws won't hold because the timber is rotten, the fascia needs replacing first.
What you can check safely
From the ground during rain, watch where the water escapes. Note whether it's at a joint, over the front, or at the downpipe. Look for staining on the wall and check whether the downpipe is carrying water. Photos help a lot when you get in touch. Avoid leaning a ladder against plastic gutters, which can crack them, and don't work at height alone.
Repair or replace?
One leaking joint or a short sag is a straightforward repair. If seals are failing all along the run, the plastic has gone brittle, or the gutter keeps overflowing because it's undersized, new guttering is better value. See our gutter replacement page for the options, and the guttering, fascias and soffits page for all our roofline work.
Need it sorted?
Book a gutter repair or use the quote form. We cover Somerset and Devon up to about 50 miles from Taunton, and every quote is free and in writing. Call 07399 680142.