OUTDOOR & GARDEN

Fix a leaking gutter joint

Stop a leaking gutter joint by cleaning it, resealing or rebolting it, then testing with water before tidying up.

GJ-01Set up safely and find the leakPosition your ladder on firm, level ground and follow your usual ladder safety checks before you climb. Run water through the gutter with a hose or watering can and watch where it drips to pinpoint the exact joint. Mark the leaking joint with a strip of tape so you can find it again quickly once you're back up the ladder.
1 roll · Masking tape
GJ-02Clear debris from the gutterScoop out leaves, moss and silt for about 300mm either side of the joint using a gloved hand or small trowel. Wipe the gutter and the joint itself dry with a cloth so you can see the fault clearly. While you're there, check the brackets either side of the joint for looseness or bending.
1 each · Bucket
1 each · Cloth
1 pair · Gardening gloves
GJ-03Work out what type of gutter you haveMost gutters fitted since the 1970s are plastic (PVC) — lightweight, usually grey, black or white, with clip-together joints. Older properties often have cast iron or metal gutters, which are heavier, painted, and bolted together at the joints. Check which you have before you go further, because the two need different repairs.
GJ-04Plastic (PVC) gutter: repair the jointUnclip or unsnap the union bracket at the joint and lift the gutter section clear. Wipe off old grit and sealant, then check the rubber seal inside the union for cracks or flattening. Fit a new seal if it's worn, run a thin bead of gutter sealant around the joint, and clip it firmly back together.
1 each · Replacement rubber union seal
1 tube · Gutter sealant
GJ-05Cast iron or metal gutter: repair the jointUndo the nut and bolt holding the two sections together and separate them. Wire-brush both faces back to clean metal, removing rust, flaking paint and old mastic. Apply a bead of gutter mastic or sealant to both faces, rebolt the joint, and wipe away any excess before it skins over.
1 each · Wire brush
1 tube · Gutter mastic or bituminous sealant
1 each · Replacement nut and bolt
GJ-06Check and refix a loose bracketA leaking joint is often caused by a slipped bracket changing the gutter's fall, so check both brackets are tight before you finish. If a bracket is loose in a timber fascia board, remove it, plug the old screw hole with a wood filler dowel and glue, then drive a new 40mm stainless steel screw slightly clear of the old hole. If there's no fascia and the bracket fixes straight into brick or block, use a cable and pipe detector first, but still treat it as a guide only — detectors miss cables and pipes that run outside the usual zones, especially near soil stacks or outdoor lighting circuits. Find your stopcock (usually under the kitchen sink) and check it turns, so you can shut the water off fast if you hit a pipe, and if you're at all unsure, isolate the relevant circuit at the consumer unit before you drill. Drill a 6mm pilot hole 50mm deep, push in a masonry wall plug, and drive a 50mm screw through the bracket into it.
1 each · Cable and pipe detector
1 set · Wooden filler dowel and wood glue
2 each · Stainless steel screw 40mm
2 each · Masonry wall plug (Rawlplug)
2 each · Masonry screw 50mm
1 each · 6mm masonry drill bit
GJ-07Check the gutter fallHold a spirit level along the gutter run near the repaired joint; it should show a gentle drop of about 5mm per 3m toward the downpipe. If the joint dips or humps, loosen the brackets either side, adjust the level, and retighten. A wrong fall lets water pool at the joint and start the leak again.
GJ-08Test the repairPour a full bucket of water down the gutter from the highest point and watch the repaired joint closely as it passes. Check underneath for drips and let any sealant cure for the time stated on the tube, usually 24 hours, before heavy rain is expected. If it still leaks, undo the joint and repeat the repair.
GJ-09Tidy upWipe away any excess sealant and dispose of old rubber seals, rusty bolts or offcuts responsibly. Seal the lid on any leftover sealant or mastic so it's usable next time. Fold the ladder away and put your tools back in your kit.

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