Replace a broken downpipe section

Replace a damaged downpipe section by removing the broken length, cutting a new piece to size, and refitting it securely to the wall.

DP-01Identify your downpipe material and buy matching partsMost UK homes have plastic (PVCu) downpipes, usually black, white or grey, in 68mm round or 65mm square sizes. Older or listed properties may have cast iron pipes, which are heavier and repaired differently. Measure the diameter and shape of your existing pipe, then buy a matching replacement section, a coupling piece and pipe clips from a builders' merchant.

RULES

1 each · PVCu downpipe section (2.5m)

Buy:B&QAmazon

1 each · Downpipe coupler/socket

Buy:B&QAmazon

KNOW THE RULES

If your home is listed or in a conservation area, check with your council's conservation officer before changing the pipe material or appearance - swapping cast iron for plastic can count as altering the outside of the building.

DP-02Gather your toolsYou'll need a tape measure, hacksaw or pipe saw, PVC solvent cement, pipe clips, screws or wall plugs, a cable and pipe detector, a drill, a screwdriver and a dust sheet to catch debris. Lay everything out on the ground before you go up the ladder so you don't need to keep climbing down.

1 each · Hacksaw

Buy:B&QAmazon

1 each · PVC solvent cement (250ml)

Buy:Travis PerkinsB&QAmazon

1 each · Cable and pipe detector

Buy:Tooled UpB&QAmazon

1 each · Dust sheet

Buy:Tooled UpB&QAmazon

DP-03Set up safely and support the pipePosition your ladder on firm, level ground, following safe ladder practice. Place a bucket or dust sheet below the damaged section to catch any water or debris. Check the pipe above the break is still firmly clipped so it won't fall once you cut it free.

1 each · Bucket

Buy:Tooled UpB&QAmazon

DP-04Remove the broken sectionUndo the screws holding the pipe clips above and below the damaged length, using your screwdriver or drill. Slide or twist the pipe free at the socket joints - older joints may be solvent-welded and need cutting through with a hacksaw instead. Lift the damaged section clear and set it aside.

DP-05Measure and cut the new pipe to lengthMeasure the gap left by the old section, including how far it needs to sit inside the couplings at each end. Mark this length on your new pipe and cut it square using a hacksaw or pipe saw. Smooth the cut edge with sandpaper or a file so it seats properly in the joint.

1 sheet · Sandpaper

Buy:Tooled UpB&QAmazon

DP-06Join the new sectionFor plastic pipe, apply solvent cement to the socket and pipe end, push together firmly, and hold for the time stated on the tin - usually 30 seconds. Wipe away any excess cement straight away. For cast iron, repairs usually need a specialist coupler or a plumber, as the pipe is heavy and brittle.

DP-07Refix the pipe clips to the wallDownpipe clips fix to the outside wall of your house, which is almost always solid brick, block or stone, not a stud wall - so timber and metal stud fixings don't apply here. Before drilling, use a cable and pipe detector to check for anything hidden, but still be cautious: detectors can miss deep cables, alarm wiring or pipes feeding outside taps and lights. Find your stopcock (usually under the kitchen sink) and check it turns before you start, and if you're at all unsure, turn off the relevant circuit at the consumer unit first. On solid brick or block, drill a 6mm hole about 40mm deep, insert a plastic wall plug, and fix with a 50mm screw. On rendered walls, drill through the render into the masonry behind and use a slightly longer 60mm screw so it still grips the brick or block. On timber fascia boards, feather-edge cladding or a timber-framed outbuilding, skip the plug and drive a 40mm wood screw straight into solid timber, avoiding soft or rotten wood.

1 pack · Plastic wall plugs (pack)

Buy:Travis PerkinsB&QAmazon

1 pack · 50mm screws (pack)

Buy:Travis PerkinsB&QAmazon

1 pack · 40mm wood screws (pack)

Buy:Travis PerkinsB&QAmazon

2 each · Pipe clips

Buy:B&QAmazon

DP-08Test with waterPour a bucket of water down the pipe from the top, or run a hose into the gutter above, and watch the new joints for leaks. Tighten any clips that look loose, and reapply solvent cement to any joint that weeps.

DP-09Tidy upDispose of the old pipe section - plastic can usually go in household recycling or to the tip, cast iron should go to a scrap metal recycler. Clean solvent cement off tools with the recommended cleaner and store leftover materials safely. Fold away your dust sheet and put the ladder away.

Travis Perkins and Tooled Up links are affiliate links: if you buy after clicking, we may earn a small commission at no extra cost to you. B&Q and Amazon links are plain searches and earn us nothing.

Save this as a project

Back to all guides

Related guides