Failing lead flashing is one of the most common reasons Norwich homeowners find damp patches on ceilings near chimneys, dormers, and skylights - and North Walsham Roofers carries out lead work across Norwich and the surrounding area.
Lead flashing sits at every junction where your roof meets a vertical surface: around chimney stacks, along the sides of dormers, above bay windows, and in the valleys where two roof slopes meet. When it is sound, you will never think about it. When it starts to fail, water finds its way in quickly and the damage spreads further than the leak itself.
The warning signs are not always obvious from ground level, but there are things you can check from inside and outside the property. Acting early saves money - a failed flashing caught before water has soaked into timbers or plasterwork is a straightforward lead repair. Leaving it means a bigger job and, often, secondary repair work on ceilings and roof structure too.
Damp patches or tide marks on a ceiling directly below a chimney breast or dormer are a strong signal that lead flashing is letting water in. The stain is often circular or irregular rather than a straight line, because water tracks along timbers before it shows through. You might also notice peeling wallpaper or blistering paint on a chimney breast wall, particularly after heavy rain.
A musty smell in a loft space or upper room that has no obvious cause is worth investigating. Moisture getting in through failed flashing does not always drip through to finished ceilings immediately - it soaks into insulation and timbers first, causing rot and mould that you smell before you see it.
From ground level, or from a safe vantage point such as an upstairs window looking onto a lower roof, look for these specific signs:
Lead is a naturally soft, malleable metal, and that is exactly why it works so well at roof junctions - it can be dressed tightly to masonry and shaped around awkward angles. But that softness means it moves with temperature changes, expanding in summer heat and contracting in winter cold. Over many years, repeated thermal cycling causes metal fatigue, and the lead cracks along the lines where it has been folded or fixed.
Step flashing and soaker sets on dormer cheeks work in small individual pieces precisely to allow this movement. When the pieces are too long, or fixed too rigidly, cracking happens sooner. A common problem is lead that was installed in one continuous run where it should have been cut into shorter sections - this is a workmanship issue that accelerates failure.
Mortar failure is the other main cause. The top edge of a flashing is wedged into a chase cut into the brickwork and pointed with mortar. That mortar weathers over time, especially where frost gets into it. Once the pointing breaks down, the top edge of the flashing is no longer held, and rain can get in behind the lead even if the lead itself is sound. Re-pointing the chase and re-securing the flashing is sometimes all that is needed on an otherwise sound installation.
Thermal movement can also cause lead to creep downward on a pitched surface. When you see the bottom edge of a flashing sitting proud of the surface it should be bedded against, that is thermal creep - the lead has slowly moved from its original position over many hot summers.
Finally, corrosion can affect lead where it is in contact with certain materials - runoff from new oak timbers, for example, contains tannic acid that corrodes lead over time. This is less common but worth knowing if a roof has recently had timber work done alongside lead flashing.
Chimney stacks on older properties are the most likely place to find failed lead work, for several reasons. The chimney projects above the roofline, which means it takes the full force of wind and rain from all sides. Mortar joints on exposed stacks deteriorate faster than elsewhere on the building. And chimney stacks can move slightly independently of the main roof structure, putting stress on any fixed flashing between them.
A properly detailed chimney will have a front apron flashing at the low side, stepped soakers up each side that interleave with the tiles or slates, a back gutter at the high side behind the stack, and a cover flashing over all of the above. Each element serves a specific purpose. When any one of them fails or was never installed correctly, water gets in.
Properties in and around Norwich often have chimneys that were last properly attended to decades ago. Temporary mastic repairs are widespread because they are cheap and quick, but mastic does not bond permanently to lead and fails within a few years. It is always better to cut out failed sections and re-dress in new lead than to rely on sealant.
Modern skylights have their own integral flashing kits, but lead is still used to weatherproof the junction between those kits and the surrounding tiles. When a skylight starts to leak, the fault is as often in the lead apron or side flashings as it is in the unit itself. Before assuming the skylight needs replacing, it is worth having the lead work checked.
Dormers are more complex. A dormer has a flat or pitched roof of its own, cheek walls clad in lead, slate, or tiles, and a series of junctions between all of these elements. Lead is typically used on the cheeks, in the valleys where the dormer roof meets the main slope, and above the dormer window frame. Any one of these junctions can fail independently, and tracing the exact source of a leak in a dormer can take careful investigation.
A drip in dry weather, or a barely visible damp patch, is easy to put off. The trouble is that water damage compounds. A small amount of moisture getting into a roof space each time it rains will, over one or two winters, cause timber decay, saturated insulation, and potentially damage to the masonry itself if frost gets into wet brickwork. What starts as a lead repair can become a much larger structural problem.
If you have spotted any of the signs described above on your property in Norwich, or in neighbouring villages, call us for a roof survey so we can assess exactly what the flashing is doing and advise you on what work is needed. We cover Norwich and the wider Norfolk area from our base in North Walsham.
Our lead work covers all the standard applications on domestic roofs:
We cut and dress lead to the correct Code specification for each application. The Code number (Code 3 through to Code 8 in common use) refers to the thickness of the sheet, and the right Code for a given location depends on the exposure and the size of the area being covered. Using the wrong Code - typically too thin a sheet - is another reason flashings fail prematurely.
If you are unsure whether what you are seeing is a lead flashing problem or something else, call us and describe what you have noticed. We cover Norwich and towns and villages across Norfolk including Rollesby, Martham, Holt, and Sheringham. Getting the diagnosis right before any work starts is the only way to make sure the repair actually solves the problem.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
