Lead flashing is one of the longest lasting parts of any roof, often outliving the tiles or slates around it. But a lifespan of a century is only realistic if it was fitted properly in the first place, and plenty of flashing around Bridgend was not. Here is what to expect, what shortens its life, and how to tell when yours needs attention.
Correctly fitted lead flashing should last 50 to 100 years. Older lead on Victorian terraces in Bridgend, Maesteg and Porthcawl is often original, and a good deal of it is still doing its job. Lead does not rust or rot, and the natural patina that forms on the surface protects the metal underneath.
The thickness of the lead matters. Lead is graded by code, with Code 3 being the thinnest commonly sold and Code 4 or Code 5 the usual choice for flashings. Code 4 (1.8mm thick) is the standard for chimney and abutment flashings, while Code 5 (2.24mm) is better for wider valleys and gutters. Thin Code 3 lead used to save money on a flashing job tends to fatigue and split within 15 to 25 years.
Most lead failures we see are down to installation rather than the material itself. Lead expands and contracts with temperature, and a single long piece will crack at the point of most movement. Flashings should be fitted in lengths no longer than 1.5 metres with overlaps between pieces, so each one can move independently.
The South Wales coast adds its own pressures. Salt air, driving rain and strong south westerly winds all test the fixings and mortar that hold flashing in place. Where a flashing has been pointed into a chimney with cement mortar rather than dressed into a chase and secured with lead wedges, the mortar fails long before the lead does, and water tracks in behind it.
Damp patches on the ceiling near a chimney breast are the classic sign, but by then water has usually been getting in for a while. Look first from the ground with binoculars, or check the loft after heavy rain for staining on the chimney brickwork or timbers.
Hairline cracks along the lead, especially running across the direction of the fold, mean the metal has fatigued. Lead that has slipped down or curled away from the wall has lost its fixing. Small holes or pinpricks in the surface usually mean the lead is thin and near the end of its useful life.
Small splits can be lead welded, and a lifted flashing can often be re-dressed and re-wedged in an afternoon if the lead itself is sound. Where the lead is thin, widely cracked or has been patched with sealant more than once, replacement is the better long term option. Flashing sealant and tapes are a temporary measure at best and rarely last more than a couple of winters in our weather.
Costs depend on access, scaffolding and how much lead is involved. Re-flashing a single chimney stack with Code 4 lead typically sits in the region of £400 to £900 in this area, with scaffolding or a tower adding to that if the stack is not reachable from a roof ladder. Lead is priced by weight, so a wide valley or a long abutment will cost more than a small step flashing. Always ask what code of lead is being quoted, since that is where corners are most easily cut.
Very little, but a check every few years is worthwhile. Look for cracks, lifted edges and failed pointing, and clear any moss or debris that holds water against the lead.
For lifespan, yes. Self adhesive flashing tapes and some lead substitutes last 10 to 25 years, whereas properly fitted lead should outlast the roof covering itself.
Sometimes, if it is Code 4 or thicker and free of cracks. In practice most roofers replace it during a re-roof because the cost of new lead is small compared with the scaffolding already in place.
Got a roof job in mind after reading this? Give Paul a call or send a photo, and you will get a straight answer and a free quote.