Fix It Britain

Autumn is when gutters cause the most trouble. Leaves, moss and seeds pile up, the next downpour spills over the edge, and before long you’ve got a damp patch on an inside wall or green streaks down the brickwork. The good news is that you can usually clear and fix a leaking gutter yourself in an afternoon, as long as you work safely from a ladder and pick the right fix for the problem. This guide covers the plastic (PVC) guttering found on most UK homes.

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• Difficulty: Easy to moderate (the hardest part is working safely at height)
• Time needed: Allow an afternoon for a typical single-storey or two-storey run, longer if you need to buy parts
• Best time to do it: Late autumn once most leaves have dropped, and again in spring. Pick a dry, calm day.
• Best for: Plastic gutters that overflow, drip at the joints or sag in the middle

Why gutters leak

Before you climb up, it helps to know what you’re looking for. Most leaking gutters come down to one of five causes:

• A blockage. Leaves and moss stop water reaching the downpipe, so it backs up and spills over the front edge. This is by far the most common cause.
• A failed joint seal. Plastic gutter lengths are joined with clip-on union brackets that have a rubber seal inside. Over time the seal hardens, perishes or slips, and water drips from the joint.
• The wrong fall. Gutters need a very gentle slope towards the outlet. If a section is level or slopes the wrong way, water sits and overflows.
• Sagging. A broken or loose fascia bracket lets the gutter drop, creating a dip where water pools.
• A crack or split. Plastic can become brittle with age and sunlight, and a ladder resting on it can crack it.

The easiest way to diagnose the problem is to watch the gutter from the ground during heavy rain. Note exactly where water escapes: over the edge in the middle of a run, at a joint, or at the outlet. That tells you which of the steps below you’ll need.

What you’ll need

• A sturdy leaning ladder long enough to reach comfortably, ideally with a stand-off (stay) so it rests against the wall, not the gutter
• A ladder mat or stopper if you’re on a smooth or uneven surface
• Thick waterproof gloves and safety glasses
• A gutter scoop or small plastic trowel
• A bucket with a hook, or a bin bag hooked to the ladder
• Garden hose or a watering can
• A tape measure, string line and spirit level (for fixing the fall)
• Replacement union brackets or seals, fascia brackets, or gutter sealant – only for the repairs you need
• Screwdriver or drill/driver, and stainless or zinc-plated screws for brackets
• A helper to foot the ladder and pass things up

Before buying parts, check your gutter’s profile. UK plastic gutters come in several shapes – half round, square line, deep flow and ogee are the most common – and sizes, and the parts from different brands don’t always fit each other. Take a photo of an existing bracket or joint, or a small offcut, to the shop.

Step 1: Set up your ladder safely

Falls from ladders are the real risk with this job, so take your time. Stand the ladder on firm, level ground and set it at the right angle – the usual rule is one unit out from the wall for every four units up. Don’t rest the ladder on the plastic gutter itself, as it can crack or give way. A stand-off bracket holds the ladder away from the wall and spreads the load across the brickwork.

Once you’re up, keep your body between the stiles and don’t overreach – it’s much safer to climb down and move the ladder every metre or so. Don’t stand on the top three rungs of a leaning ladder. Have someone foot the ladder, and don’t go up in wind, rain or ice. If the gutter is above a conservatory, over a steep drop or more than two storeys up, this is a job for a professional with the right access equipment.

Step 2: Clear out leaves and debris

Start at the downpipe outlet and work away from it. That way, you clear the exit first and don’t push debris into the downpipe. Scoop out leaves, moss and silt with your gutter scoop and drop it into your bucket, not onto the path below – it’s slippery and stains paving. Pay special attention to the outlet itself, where debris tends to compact into a plug.

Leaf and moss debris from gutters can go in your garden waste bin or on the compost heap. If moss on the roof keeps refilling the gutter, it’s worth tackling the roof separately – but avoid scraping or pressure-washing roof tiles yourself, as it can damage them.

Step 3: Flush the gutter and check the downpipe

Run a hose or pour a watering can into the far end of the gutter and watch the water flow. It should run steadily towards the outlet and disappear down the downpipe without pooling. Watch every joint for drips.

If water backs up at the outlet, the downpipe is blocked. Try flushing it from the top with the hose. If that doesn’t work, many downpipes have a bend (offset) near the top that pulls apart, or an access point near the bottom – remove it and clear the blockage with a length of stiff wire or a drain rod, working from below where possible. Also check the gully or drain at the bottom of the downpipe isn’t clogged with leaves.

Step 4: Fix a leaking joint

Dripping joints are the most common leak on plastic gutters, and usually the easiest to fix. Unclip the union bracket from the two gutter ends – most have clips at the front and back that you ease open with your thumbs or a flat screwdriver. Clean the inside of the union and the ends of both gutter lengths with a cloth; grit and moss stop the seal sitting flat.

Look at the rubber seal. If it’s cracked, flattened, hard or has slipped out of its groove, replace it – you can buy replacement unions that come with a seal already fitted, and some ranges sell the seals on their own. Clip the union back on, making sure both gutter ends sit within the marked limits inside the bracket so they have room to expand in hot weather.

If the seal looks fine but the joint still weeps, a thin bead of gutter sealant inside the union before reassembly can help. Think of sealant as a backup for a sound seal, not a replacement for a perished one – smearing it over the outside of a bad joint rarely lasts.

Step 5: Correct the fall and fix sagging sections

If water pools in one spot or overflows away from any joint, check the fall. Gutters need only a very slight slope towards the outlet – UK suppliers commonly quote around 1 in 600, which works out at about 5mm of drop over 3 metres. You barely see it by eye, so use a string line stretched tight between the highest and lowest brackets, or a long spirit level.

Where the gutter dips below the line, a bracket has usually worked loose, broken or been knocked out of line. Unclip the gutter, then unscrew and refix the bracket at the right height using a new screw hole in sound timber. Replace any cracked brackets. Check the manufacturer’s guidance for bracket spacing on your system, and add an extra bracket where a long run sags between two fixings.

If the screws won’t hold because the fascia board is soft or rotten, stop there. Re-fixing into rotten wood won’t last, and the fascia needs replacing first – see when to call a professional below.

Step 6: Replace a cracked section

Sealant or tape over a crack is only a stopgap. For a lasting repair, replace the damaged length. Unclip it from its brackets and unions, take it down and use it as a template for the new piece. Cut the new length with a fine-toothed hacksaw, file off any burrs, and clip it back in place, making sure each end sits correctly inside its union. On longer runs you may find it easier to replace the cracked section with a short new piece joined by an extra union.

Once all repairs are done, flush the gutter again with the hose and check every joint from the ground.

Common mistakes to avoid

• Leaning the ladder on the gutter. Plastic guttering isn’t designed to take the weight and can crack or pull off its brackets.
• Overreaching. It’s tempting to stretch for the last bit. Move the ladder instead.
• Washing debris down the downpipe. Clear by hand first, then flush, or you’ll just move the blockage underground.
• Using sealant instead of replacing seals. Sealant over a perished seal or crack rarely lasts more than a season.
• Mixing parts from different systems. Profiles vary between brands and older ranges, so check compatibility before you buy.
• Forcing gutter ends tight together. Plastic expands in hot weather. Leave the expansion gap marked inside each union.
• Ignoring the fascia. If brackets keep coming loose, the timber behind them is probably the real problem.

When to call a professional

Get a roofer or guttering specialist in if the gutter is high up, above a conservatory or extension roof, or anywhere you can’t set up a ladder safely. The same goes for rotten fascia boards, cast iron gutters (they’re very heavy and awkward to handle) and a system that’s cracked or sagging along most of its length, where replacing the whole run is often better value than patching it.

Some older homes have grey cement gutters and downpipes that may contain asbestos. Don’t drill, cut, break or scrub them – get advice from a licensed asbestos professional or your local council before doing any work on them.

Frequently asked questions

How often should I clean my gutters?

For most homes, once a year in late autumn is a good minimum, after the bulk of the leaves have fallen. If you have large trees nearby or a mossy roof, a second check in spring is worth doing.

Why is water coming over the front of my gutter?

Usually because of a blockage, either in the gutter or the downpipe, so the water can’t drain away fast enough. If the gutter is clear, check the fall – a section that’s level or sloping away from the outlet will overflow in heavy rain.

Can I just use sealant on a leaking gutter joint?

Only as a backup. If the rubber seal inside the union is cracked or perished, replace it or fit a new union. Sealant works best as a thin bead inside a clean joint with a sound seal.

Are gutter guards worth fitting?

Mesh guards or brush inserts can cut down on how often you need to clear out leaves, especially under trees. They still need checking and cleaning from time to time, as fine debris and moss can build up on top of or inside them.

Who is responsible for shared gutters on a terraced or semi-detached house?

Generally each owner looks after the guttering on their own property, but where a gutter or downpipe is shared it’s best to agree repairs with your neighbour first. If you rent, report leaking gutters to your landlord rather than repairing them yourself.

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