How a gutter joint is put together
Plastic guttering is usually made of straight lengths clipped into union brackets, corner pieces and running outlets. Each of these fittings contains a rubber gasket that the gutter presses into, making a watertight seal while still allowing the plastic to expand and contract with temperature. Older cast iron and some metal systems are bolted together with a sealing compound between the sections instead.
Either way, the joint is the weakest point of the run. It is where two parts meet, where movement concentrates and where a seal has to last through years of sun, frost and standing water.
Why gutter joints start leaking
Rubber gaskets harden and shrink as they age, especially on south-facing elevations that bake in summer sun. Once they lose their flexibility they no longer grip the gutter, and water seeps past. Frost can then work into the gap.
Movement is the other big cause. A length that has dropped because a bracket worked loose pulls slightly out of its union. Debris can also hold water against a joint for days at a time, so a seal that would cope with brief rain starts to weep under constant pressure.
How we repair a leaking joint
First the run is cleared so the joint is clean and visible, and we check whether the gutter is still properly seated and falling towards its outlet. If the fitting is sound but the seal has failed, the joint is cleaned and resealed. If the fitting itself is cracked or the gutter has pulled out, the joint is remade so the lengths sit correctly.
Where a dropped bracket caused the problem, that is put right too, otherwise a new seal would soon be pulled apart again. We then explain what was done, with photographs.
Sealant from a tube: why it often fails
Squeezing sealant over the outside of a dripping joint is a common quick fix. It rarely lasts, because the leak is coming from inside the union where the gasket meets the gutter. Sealant applied to a damp, dirty surface does not bond well, and if the gutter is still moving it simply cracks away.
If you do try a temporary fix on a low joint, make sure the surface is clean and completely dry and work from a properly footed ladder. Anything at first-floor height or above, or above a conservatory roof, is better left to us.
Corners and outlets need particular care
Corners collect debris because water slows as it changes direction, so their seals spend more time under water than straight unions. Running outlets carry all the water from a run into the downpipe, and a blocked pipe below can back water up until it forces past the outlet seal.
When a corner or outlet leaks, we check the downpipe and the adjoining lengths as well as the fitting itself. Fixing only the visible drip can leave the cause in place.
One joint, or the whole run?
If one joint has failed, others of the same age may not be far behind. We will tell you if neighbouring unions look close to failing, so you can choose to deal with them while access is set up, but you are never obliged to.
Where the gutter itself is brittle, cracked in several places or badly distorted, resealing joints will not give a lasting result. In that case we say so clearly, and our guide to the signs gutters need replacing explains what to look for.
What to send when a joint drips
A clear photograph of the dripping joint from the ground, and a wider shot showing the whole run, helps us see whether the length either side has dropped. Tell us whether the drip happens in every shower or only in heavy rain, since that hints at whether water is backing up.
If several joints are dripping, number them on a photo or describe them by position. We will then explain which can be resealed and whether any fitting needs remaking.
Common questions
How do you fix a leaking gutter joint?
Clear the run, check the gutter is seated and falling correctly, then reseal the joint or remake it if the fitting is damaged. Any dropped bracket is corrected too.
Can I just put sealant on the outside of the joint?
It may stop a drip briefly, but the leak usually comes from inside the union. Sealant on a damp or moving joint tends to crack away.
Why does the same corner keep leaking?
Corners collect debris and hold water, and a blocked downpipe nearby can force water past the seal. Both need checking alongside the joint.
Is gutter joint repair part of gutter cleaning?
No, it is a separate repair. If cleaning reveals a leaking joint, we describe it and quote the repair for you to approve.
How long does a resealed gutter joint last?
That depends on the age of the gutter, its exposure and whether the cause, such as a dropped bracket, has been corrected. We explain what we did and why.
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Based in Petersfield, working across Hampshire · Surrey · Sussex, insured to £5,000,000 public liability.