How to Fix a Leaking Gutter: DIY Fixes vs Professional Repair

A leaking gutter might seem like a minor annoyance, but left unaddressed it can cause serious damage to your home. Water running down external walls leads to damp, staining, and eventually structural issues. In this guide, we explain how to diagnose the source of a gutter leak, the DIY fixes available, and when it makes sense to call a professional — particularly for older properties across Kent and South East London.

Step 1: Diagnose the Source of the Leak

Before you can fix a leak, you need to find it. Not all gutter leaks are obvious — water can travel along the outside of the gutter and drip some distance from the actual leak point. The best time to diagnose is during or just after rainfall.

Common Leak Locations

• Gutter joints — the most common source. Where two lengths of guttering connect, the seal can degrade over time. This is especially prevalent on uPVC guttering that has been in place for 15+ years.
• Gutter brackets/fixings — if a bracket has worked loose, the gutter can sag and water pools rather than flowing to the downpipe. The pooling water then overflows or finds weak points.
• Cracks and holes — uPVC gutters can crack from impact damage or UV degradation. Cast iron gutters on older properties in Bromley, Lewisham, and Greenwich can develop rust holes.
• Downpipe connections — where the gutter meets the outlet and downpipe, seals can fail or the outlet can become partially blocked, causing overflow.
• Overflow from blockage — sometimes what looks like a leak is actually an overflow caused by a blocked gutter. Always rule this out first with a thorough gutter clean.

Top tip: If you cannot spot the leak during rain, have someone direct a garden hose into the gutter while you watch from below. Work methodically from the far end towards the downpipe.

Step 2: DIY Fixes for Common Gutter Leaks

Fixing a Leaking Gutter Joint (uPVC)

Leaking joints are the single most common gutter problem we see on properties across Kent, Sussex, and South East London. Here is how to fix one yourself:

1. Wait for a dry day — sealant will not adhere to wet surfaces
2. Set up your ladder safely with a standoff bracket
3. Carefully unclip the gutter section from the joint connector
4. Remove the old rubber seal or degraded sealant from inside the joint
5. Clean both surfaces thoroughly with a cloth and some white spirit
6. Apply a bead of quality gutter sealant around the inside of the joint connector
7. Refit the gutter section, pressing firmly into the connector until it clips into place
8. Wipe away any excess sealant with a damp cloth
9. Test with water from a hose before packing up

For advice on choosing the right sealant, see our gutter sealant guide, which compares silicone, butyl, and mastic options for different gutter materials.

Patching Cracks and Small Holes

For small cracks in uPVC guttering, a gutter repair tape or patch kit can provide a temporary fix. Clean the area thoroughly, ensure it is completely dry, and apply the self-adhesive repair patch over the crack. For a more permanent solution, apply a generous layer of gutter sealant over the patch.

Bear in mind that patches are a temporary measure. If the guttering has multiple cracks or is generally degraded, replacement is the more cost-effective long-term solution.

Tightening Loose Brackets

If a bracket has come loose from the fascia, the gutter will sag and water will pool. In many cases, you can simply re-screw the bracket into a slightly different position on the fascia board. Use stainless steel screws rather than the original fixings, as these resist rust. If the fascia board itself is soft or rotten, the bracket will not hold — you may need fascia board replacement before re-fixing the gutter.

Special Considerations for Cast Iron Gutters

Many period properties in areas like Bromley, Lewisham, Greenwich, Tunbridge Wells, and Sevenoaks still have their original cast iron guttering. Cast iron is extremely durable but does corrode over time, and repairs require a different approach to uPVC.

• Rust holes: Small rust spots can be treated with a wire brush to remove loose rust, then primed with a rust-inhibiting metal primer and sealed with a bituminous compound or epoxy repair paste.
• Leaking joints: Cast iron gutter joints are typically sealed with putty and bolted together. To repair, you need to remove the old bolt, clean out the degraded putty, apply new putty or mastic, and refit with a new galvanised bolt.
• Cracked sections: Unlike uPVC, cracked cast iron cannot be patched effectively. The affected section needs to be replaced. Matching profiles for period guttering can be sourced from specialist suppliers, though it is worth considering a like-for-like cast aluminium replacement for a maintenance-free alternative.

Important: If your property is in a conservation area — common in parts of Tunbridge Wells, Sevenoaks, and Greenwich — you may need to maintain the original gutter style. Check with your local planning authority before replacing cast iron with uPVC.

Temporary vs Permanent Fixes

It is important to understand which repairs are temporary and which are lasting solutions:

• Gutter repair tape: Temporary (6–12 months). Good for an emergency fix until you can arrange a proper repair.
• Gutter sealant on joints: Semi-permanent (2–5 years depending on quality and application).
• New joint connectors/seals: Permanent fix. The rubber seals in uPVC joints should last 10–15 years if properly fitted.
• Section replacement: Permanent. If a section is cracked, replacing it is always better than patching.

When to Call a Professional

Some gutter repairs are straightforward DIY jobs. Others really do require professional help:

• Multiple leaks — if you have leaks at several points, the guttering may be reaching the end of its life
• Cast iron repairs — the weight and brittleness of cast iron makes it hazardous to work with on a ladder
• High or difficult access — two-storey properties, overhanging extensions, and steep roofs
• Rotten fascia boards — if brackets will not hold because the fascia is damaged, the fascia needs replacing first
• Persistent leaks after DIY repair — if your fix has not worked, there may be an underlying issue

At Gutter Maintenance Tech Ltd, we carry out gutter repairs and replacements across Kent, Sussex, and South East London. Our team works in Bromley, Orpington, Beckenham, Croydon, Bexleyheath, Chislehurst, Swanley, Dartford, Maidstone, Tonbridge, Southborough, Crowborough, Paddock Wood, and Ashford. We offer a two-year guarantee on all repair work and a five-year guarantee on replacements. We are SafeContractor approved and Trading Standards registered with 150+ five-star reviews.

Frequently Asked Questions

How much does it cost to fix a leaking gutter?

A simple joint reseal typically costs £40–£80 as part of a service visit. Replacing a section of uPVC guttering is usually £80–£150 depending on access. Cast iron repairs cost more due to the specialist skills and materials involved. We provide free quotes for all work across our service areas.

Can I use silicone sealant on gutters?

Standard bathroom silicone is not ideal for gutters. It does not adhere well to wet surfaces and can peel away. Use a dedicated gutter sealant such as a butyl-based or hybrid polymer product. See our gutter sealant guide for specific product recommendations.

Why does my gutter leak only in heavy rain?

This usually indicates either a partial blockage (the gutter copes with light rain but overflows in heavy downpours) or insufficient gutter capacity. Some older properties in Kent and Sussex have undersized guttering that was adequate when originally installed but cannot handle modern rainfall intensities. Upgrading to a larger profile gutter or adding additional downpipes can resolve this.

Is a leaking gutter covered by home insurance?

Generally, no. Home insurance covers sudden, unexpected damage (such as storm damage) but not wear and tear or gradual deterioration. However, if a leaking gutter causes internal damp or structural damage, the resulting damage may be covered. Check your specific policy.

A leaking gutter is always worth addressing promptly. What starts as a drip can lead to hundreds or thousands of pounds in damp repairs if left. Whether you fix it yourself or call in our team, do not ignore it. For professional gutter repairs anywhere in Kent, Sussex, or South East London, call Gutter Maintenance Tech Ltd on 0204 541 7121 (London) or 01892 337966 (Kent).