The short answer
Flashing is the strip of lead, zinc or other metal that seals where a slope meets a wall, chimney or dormer. When wind lifts it, rain can run behind it into the structure. Keep clear of the roof, note where water is arriving inside, and have it covered temporarily, then refixed or replaced once someone can see the cause.
Spotting flashing that has lifted or gone
Flashing is the thin metal skirt that covers the seam between sloping roof and anything rising out of it, such as a chimney stack, a gable end, the side of a dormer or a porch roof. On most houses it is lead, though zinc, aluminium and cheaper bitumen strips turn up on extensions and garages. Wind gets under a loose edge, peels it back like the lid of a tin, and sometimes carries the whole piece into the garden.
From the ground, look for a bright strip of metal lying in the flowerbed, a flap standing proud of the brickwork, or a dark gap along the line where the slope runs up to the wall. Binoculars help. Inside, the clues are a brown stain on a chimney breast, damp wallpaper beside a dormer, or drips in the loft directly under the junction.
Never go up to look. A lifted sheet of lead has a sharp edge, and a wet roof in a gusty wind is no place to find that out. Ladders against a wet gable are just as risky, and the damage will still be there when a roofer arrives with the right access.
Keeping water out until the repair
The aim is to stop rain reaching the timbers, nothing more. Put a bucket under any drip, move furniture and electrical items out of the way, and lift the loft insulation back from wet timber if you can reach it safely from the hatch. Photograph the damage, and the stain as it spreads, saving each picture with its date.
A roofer can make the junction safe by fixing a temporary covering over the gap, usually a sheet of lead-substitute strip or a tarpaulin battened down across the junction. Leaks jump the queue with us, and the opening visit is aimed at making the building watertight before anything else. Our page on using a roof tarpaulin explains what a temporary cover can and cannot do, and why it is a stop-gap rather than a repair.
Do not push mastic or expanding foam into the gap yourself. It traps water behind the sealant, hides the real fault and makes the later repair slower, because every trace has to be cut out before new lead can be dressed in.
How lead flashing is refixed properly
A proper repair starts by finding why the flashing failed. Sometimes the lead was never tucked far enough into the mortar joint. Sometimes the mortar has perished and the lead has loosened. Sometimes the piece was simply too long or too lightweight for the exposure.
Lead is sold in codes, which are thicknesses. Code 4 is the usual weight for ordinary flashing, with Code 5 chosen where the run is exposed or long. Flashing is cut and dressed into a raked-out joint, wedged, and pointed. On a chimney it is built in stages: a base apron at the front, stepped pieces climbing each side, and a back gutter tucked behind. Each piece laps over the one below, so water keeps travelling outwards and away from the brickwork.
Where a long run has blown off, patching the end rarely works. Replacing the whole run is cleaner and gives a joint that will not lift at the next gust.
What affects the cost
The price rests on how much flashing has to be replaced, how high it sits, and what else was damaged when it went. A single short piece beside a low porch is a small job. A stepped run up a tall chimney, which may need scaffold access, is another thing entirely.
For a sense of scale, MyBuilder's chimney repair guide, updated in August 2026, puts a flashing repair at £250 to £1,200. Checkatrade's repair guide, updated in October 2026, prices Code 5 lead flashing at £50 to £70 per metre and stepped flashing at £80 to £120 per metre, excluding VAT. Those are typical UK figures and say nothing firm about your roof. When quotes arrive, ask each firm if VAT and scaffold hire are counted in the figure.
Rotten battens or damp boards behind the flashing add to the work, and you only find them once the old lead is off. The written quote follows the survey.
Insurance and records
If you think the damage was caused by a storm, tell your insurer early. ABI advice issued for Storm Eunice in 2022 urged householders to phone the insurer straight away and, where emergency repairs looked necessary, to talk to the insurer before booking them. Keep every receipt. Our page on whether a roof leak is worth claiming weighs up the excess and the wear-and-tear question.
Flashing that has been loose for months can be treated as maintenance rather than storm damage, so dated photographs matter. Whether a claim succeeds is between you and your insurer. Our part is to show you what we found in photographs and to put the repair in writing.
Where a blown-off flashing is part of wider damage, accidental damage to a roof and a fallen tree on a roof cover those situations.
Why we survey before we quote
One lifted strip often points to others nearby that have not gone yet. When we survey, we walk the full length of each junction, test the pointing and take pictures of every defect, so the repair covers the weak spots as well as the one that failed. The fix we propose is the smallest that cures the fault. Our workmanship carries a written 10-year guarantee. When we leave, the roof, drive and garden are tidy. To book a survey, ring 01793 626096, drop us a WhatsApp or complete the form on this page. Our emergency roof repairs page sets out the wider picture.