How often should roof flashing be replaced?

Roof flashing has no service interval, and treating it like one is how leaks get missed. It goes when the detailing goes.

Scott has spent more than 36 years on Surrey roofs, still answers the phone himself and hands over a 25-year written workmanship guarantee that covers repairs as well as new roofs. Whether you need lead work & flashing or lead work & flashing services Godalming, we cover the whole area.

Call 07428 300474 any time and a real person answers, day, night or weekend.

How often should roof flashing be replaced?

Roof flashing should be replaced when it fails rather than on a fixed schedule, and good milled lead laid properly will often run 60 years or more, while cement fillets, mortar-only detailing and thin modern substitutes commonly need attention within 15 to 25 years. Inspect every few years and replace on evidence, not on age alone.

What actually decides how long flashing lasts

Two pieces of flashing on the same street can be 40 years apart in useful life, and it is almost never the metal that decides it. It is the detailing. Lead that has been cut to the right size, dressed without being stretched thin, wedged and pointed into a raked joint and given room to move with temperature will outlive the tiles around it. Lead that was cut too long in one piece, nailed tight at both ends and then buttered over with sand and cement will split along a fatigue line within a decade or two, because the metal expands and contracts every single day and something has to give.

Position matters too. A chimney on the weather side, an abutment under a valley discharge, a step flashing on a south-facing wall that bakes and then cools fast: all of those work harder than a quiet back-slope apron. Cement fillets are the usual culprit we find on Surrey properties, often sitting where lead should be, cracked and letting water track behind them. Lead Sheet Association guidance is clear enough on sizes, laps and fixing centres, and where that guidance has been followed the flashing tends to be the last thing on the roof that needs touching.

Whether you need lead work & flashing or lead work & flashing in Guildford, we cover the whole area, and the honest answer on most first visits is that the flashing itself is fine and the pointing or the fillet around it is not.

The signs that bring the replacement date forward

Flashing rarely fails quietly. It tells you, usually months before the ceiling does. Worth a look from the ground with binoculars, or from a safe upstairs window, a couple of times a year and after any real gale.

• Cracks or a fine split line running across a lead upstand or apron, often dead straight, which is thermal fatigue rather than damage.
• Lifted or lapping edges where wedges have dropped out and the wind has got underneath and rolled the metal back.
• Cement fillet crumbling at a chimney or abutment, with pieces on the roof slope or in the gutter.
• White or grey staining on brickwork below a flashing line, showing water has been running down the wall face for a while.
• Damp patches inside in a bedroom ceiling corner or on a chimney breast, particularly after wind-driven rain rather than steady rain.
• Very thin, brittle, dull lead that has been repeatedly patched, or aluminium and felt-based strips used as a shortcut on a previous repair.

Any one of those means the flashing needs looking at properly. Two or three together usually means the detail wants stripping and remaking rather than patching again, because each patch buys less time than the one before it.

The same team covers lead work & flashing in Woking.

Replacing the flashing against repairing the detail

Most jobs split into three. A localised repair, where a couple of wedges and a re-point restore a sound flashing that has simply loosened. A remake of one detail, where a chimney gets stripped of the old fillet and given proper front apron, step and back gutter in the right code of lead. Or a full renewal, where the whole abutment or every chimney on the roof is done in one go because the same age and the same original detailing means the rest is a season or two behind.

Deciding between them is a matter of looking, not guessing. A free survey, with a drone view where the chimney is awkward to reach, sorts it out quickly, and if a smaller repair will hold for years we say so rather than selling a new roof. Whether you need lead work & flashing or lead work & flashing in Woking, we cover the whole area, and the price comes back fixed and in writing before anybody starts.

One thing worth saying plainly: renewing flashing is not a cosmetic job. A chimney flashing that has been leaking for two winters has usually been wetting timber, plaster and sometimes the top of a wall plate. Getting the metal right stops the cause. The rest follows.

Fitting flashing renewal into the rest of the roof

Timing matters as much as frequency. If a roof is within a few years of a reroof, remaking every flashing now and again then is money spent twice, so it usually makes sense to do a holding repair and then renew the leadwork properly as part of the reroof, when the tiles are off and the details can be built from the brickwork out. Fixing and wind uplift on the new covering falls under BS 5534, and the flashings get sized and lapped to suit rather than being squeezed in afterwards.

The other way round, a sound roof with a failing chimney flashing wants the flashing done and nothing else. There is no sense disturbing a covering that has 20 years left in it. Work done by our own experienced local roofers, and the 25-year written workmanship guarantee covers repairs and leadwork, not only new roofs, so a remade chimney detail is backed the same as a full reroof would be.

Scott has spent more than 36 years on Surrey roofs, and the pattern is consistent: lead fails on the day it was fitted, not on the day it splits. Get the detail right once and the replacement question moves a generation down the road.

Four things to take away

• Well-detailed milled lead can run 60 years or more, so there is no routine replacement interval to diarise.
• Cement fillets and thin patched substitutes are the parts that typically fail inside 15 to 25 years.
• Replace on evidence: splits, lifted edges, crumbling fillets, wall staining or internal damp after wind-driven rain.
• If a reroof is close, hold the flashing and renew it properly with the new covering rather than paying twice.