How to Fix a Leaking Gutter (UK Parts, Prices and When to Stop)

Most gutter leaks come down to a £6 part and forty minutes of work. The catch is that the part sits four metres above a concrete path, and the difference between a repair that lasts fifteen years and one that fails by November is all in the preparation done before the sealant leaves the tube.

We have stripped off sound guttering because a homeowner was told from the pavement that the whole run was shot, and seen a bedroom wall ruined across two winters by one dripping joint nobody could reach. Here is the diagnosis, the repair and honest numbers.

Gutter work puts you side-on at the top of a ladder with both hands busy, which causes more serious DIY injuries in the UK than any power tool.

• •Pitch the ladder at 75 degrees, one metre out for every four up, on a board if the ground is soft.
• •Never rest the ladder on the guttering. A stand-off (£25-£45 at Screwfix) holds you clear of the fascia.
• •Keep your belt buckle between the stiles. A 4m run needs three repositionings, not one long lean.
• •Above single-storey eaves, or for anything needing two hands, hire an alloy tower: £70-£120 a week.
• •Before raising an aluminium ladder, check where the overhead electricity cable lands — on older terraces it arrives at the eaves.
• •Grey cement guttering on a pre-2000 garage may be asbestos cement: do not cut, drill or pressure-wash it.
• •Cast iron is heavy — 15kg for a 1.8m length — so it is a two-person job from a tower.

Nine out of ten uPVC leaks are one of three faults: a perished EPDM seal in a union bracket, a hairline split, or a run dropped out of level so water stands and creeps over a joint.

• •Union bracket with new EPDM seal, £3-£6. Photograph the profile first — half-round, square-line and ogee are not interchangeable.
• •Fascia brackets, £1.50-£3 each, fixed at 800mm centres and tightened to 600mm on exposed elevations.
• •Gutter and downpipe: £7-£11 for 2m of half-round, £9-£14 for 2.5m of 68mm downpipe.
• •MS polymer sealant such as CT1, £8-£14 a tube. Bathroom silicone will not bond to cold, damp uPVC.
• •Butyl gutter repair tape, 100mm x 5m, £15-£25, for splits longer than 100mm.
• •Filling knife, water-pump pliers, 120-grit abrasive, methylated spirits, rags, a hose and a bucket.
• •Washing-up liquid as a seal lubricant — never petroleum jelly, which destroys EPDM.

Allow 30-45 minutes to reseal one union joint once the ladder is set, 45 minutes plus cure time for a hairline split, and up to 2.5 hours to re-hang a 4m run. A ladder and stand-off is £120-£220, so buy once — our ladder buying guide covers what lasts.

Paid, a handyman is £30-£45 an hour and a two-man roofing firm £200-£300 a day, £280-£380 in London and the South East. Minimum charges of £70-£120 are why a fifteen-minute repair never costs fifteen minutes of money.

Watch where the money goes. A £120 joint repair contains £6-£10 of materials; the rest is access and risk, which is why small jobs look dear. On a full replacement expect roughly 30-35% materials to 65-70% labour, with scaffolding the swing factor at £400-£900 per two-storey elevation — added to a bungalow job, that is padding. Our gutter installation cost guide breaks replacement down by property type.

• •Reseal or replace one leaking union joint, ladder access: £80-£150
• •Replace a damaged 3-4m section, single storey: £130-£240
• •Re-hang a full run, correct the fall, new brackets: £200-£400
• •Clear a blocked downpipe and the gulley beneath: £70-£140
• •Full uPVC replacement, three-bed semi at 25-35 linear metres: £900-£1,800
• •Cast iron replacement on a period property: £3,500-£9,000

• •1. Find the real leak, not the wet patch. Run a hose in two metres upstream while someone watches from below: water tracks along the underside of uPVC, so the drip shows 300-600mm downhill of the fault.
• •2. Clear the run first, because a gutter holding silt weeps at every joint; our safe gutter cleaning method avoids wrecking the brackets.
• •3. Check the fall with a string line: 3mm of drop per metre to the outlet. Standing water over 5mm deep means the brackets are at fault, not the seal.
• •4. Squeeze the gutter sides inward, release the clip, lift the section out and peel out the old seal. Check the bracket body for cracks while it is down.
• •5. Scrape the seal channel, abrade both gutter ends with 120-grit and wipe with meths. Dirty surfaces cause most repairs that fail inside a year.
• •6. Fit the new seal dry, smear washing-up liquid across it and clip the gutter back against the moulded stops, leaving the marked expansion gap. uPVC moves about 1mm per metre a year; butted tight, it splits.
• •7. For a hairline crack work from inside: dry, abrade, degrease, then lay a 3mm bead of MS polymer 25mm either side, tooled flat with a wet finger. Butyl tape anything over 100mm.
• •8. Test it: plug the outlet with a rag, fill the run, pull the rag and watch every joint for three minutes, checking behind for water tracking down the fascia.

• •Still dripping after resealing: contamination, or the wrong product. Bathroom silicone on damp uPVC peels away in one strip within a season.
• •Overshooting at one spot in heavy rain: the roofing felt has sagged into the gutter or stops short of it. An eaves protector tray, £4-£7, prevents the damp patch that shows at the top of an upstairs wall.
• •Downpipe weeping at the swan-neck only in downpours: those joints are push-fit by design, so the real fault is a partial blockage lower down.
• •Green staining down the wall: chronic slow overflow that saturates brickwork and eventually appears indoors — see our damp and mould guide.
• •Gulley backing up in every downpour: the gutter is fine, the ground drainage is not. Improving garden drainage is the actual fix.

Stop and pay someone if the gutter is two storeys up, sits above a conservatory roof, is cast iron, or runs behind a parapet or into a valley. If the fascia behind it is soft, that is joinery, not drainage.

Get two quotes over £400 and compare what each says is wrong, not just the totals. If both land on replacement, ask which failure they saw: perished ogee joints, sun-degraded plastic, rusted cast iron ears. Signs your gutters need replacing sets out what genuine end-of-life guttering looks like.

• •Good sign: a written quote naming profile and material, with labour, materials and access listed separately.
• •Good sign: a firm willing to do the £110 joint repair, and photographs of the defect taken from the ladder before work is agreed.
• •Warning sign: a price quoted from the pavement, or a cold-caller conveniently working on a roof nearby — most UK doorstep gutter scams open that way.
• •Warning sign: scaffolding priced into a bungalow, cash only, or a large deposit before anything is ordered.