If your roof is leaking around a chimney, dormer or valley in North Walsham, failed lead flashing is one of the most likely causes - and getting it sorted properly matters more than getting it sorted fast.
Lead is the material used to seal the joints where your roof meets a vertical surface - a chimney stack, a parapet wall, a dormer, or a change in roof plane. It is also used in valleys (the channels where two roof slopes meet) and as a flat roof covering on smaller areas such as bay tops, porch roofs and flat dormers. Done properly, lead work outlasts almost every other roofing material, with well-fitted lead lasting 50 to 80 years in normal conditions.
The key word is properly. Lead sheet is worked by hand on site, dressed into shape using specialist tools so it sits tight to every surface without gaps or lifting edges. It is fixed using clips that hold it securely while still allowing it to expand and contract with temperature changes - because lead moves significantly between a cold morning and a warm afternoon, and fixings that do not allow for that movement will cause the lead to crack or pull away within a few years.
Every section of lead used should be the correct code for the job. Lead sheet is graded by weight and thickness, from Code 3 through to Code 8. Valleys on pitched roofs typically need Code 4 or Code 5; chimney flashings generally call for Code 4; flat roof coverings on bays or porches usually need Code 5 or Code 6. Using underweight lead because it is cheaper is one of the reasons lead work fails prematurely.
Most residential lead work falls into one of these categories:
The most common reason flashing fails is age combined with the natural movement of lead over many cycles of heating and cooling. Older properties often have lead that was fitted 40 or 50 years ago and has simply reached the end of its useful life. The lead becomes rigid, small cracks appear, and water works its way under the flashing at points where it has lifted away from the brick or tile.
A second common cause is mortar deterioration. The top edge of a chimney flashing is typically tucked into a horizontal mortar joint and held with a bead of pointing. When that mortar crumbles - which it does eventually, especially on older brickwork exposed to driving rain - the flashing loses its seal at the top edge. Water tracks behind it and appears inside the house, sometimes at a point that looks completely unrelated to the chimney.
Poor original workmanship is also a factor on some properties. Lead that was laid without adequate fall, fixed rigidly without movement clips, or cut too short at the overlap will fail well before its time. On properties where a cowboy job was done at some point, the lead itself may still look intact while the fixings or the laps are the problem.
Finally, physical damage - from a fallen branch, from someone walking on the roof carelessly, or from a poorly secured aerial - can split or puncture lead that would otherwise last many more years.
Water staining on a ceiling below a chimney breast is the classic sign. So is damp appearing on a chimney breast wall, particularly after persistent rain. If water appears inside only during or after heavy rain and dries out when the weather improves, the source is almost certainly the roof rather than rising damp or condensation.
Valleys that are blocked or deteriorating show up differently - you may notice water overflowing the valley rather than running down it in heavy rain, or damp patches on ceilings in the angle of a hip or the junction between a main roof and an extension.
On flat lead roofs over bay windows or porches, the first signs of failure are usually blistering or cracking on the lead surface, or damp patches on the ceiling of the bay below. Lead can also lift at the drip edge and allow water to run behind the fascia board rather than into the gutter.
This section matters more than most people realise. The gap between spotting a problem and having a roofer on site can be several days, and what you do - or do not do - in that time can make a real difference to the extent of any damage inside the property.
Move possessions away from the damp area. If water is coming through a ceiling, move furniture, rugs, electrical equipment and anything else that can be damaged away from the affected zone. Water travels along joists and ceiling plaster before it drips, so the drip point is rarely directly below the roof fault. Err on the side of moving things further than you think necessary.
Protect what you cannot move. Lay polythene sheeting or old towels over anything in the affected area. If water is collecting in a ceiling and the plaster looks swollen or the paint is bubbling, place a bucket underneath and, if there is a clear collection point, you can carefully make a small hole in the plaster to allow the water to drain in a controlled way rather than bringing down a larger section of ceiling without warning. Do this only if the ceiling is already visibly sagging - not as a precaution.
Photograph everything. Take photos of the damp patch or staining, the ceiling, and if you can see the roof from a safe vantage point, the area around the chimney or valley. These photographs help a roofer diagnose the problem more quickly and are useful if you need to make a claim on your buildings insurance.
Turn off electrics in the affected area if water is near fittings. If a ceiling light fitting, a socket, or any wiring is in or near the wet zone, switch off the relevant circuit at the consumer unit as a precaution. Wet insulation and plaster dry slowly, so leave the circuit off until you are confident everything is dry, not just when the rain stops.
Contact your buildings insurer. Most policies cover sudden damage from roof leaks, though they typically do not cover the repair to the roof itself - just the resulting damage inside. Report the problem promptly rather than waiting until after the repair, as some policies require early notification. Keep receipts for anything you buy to limit the damage.
Keep a note of when the problem started and what weather preceded it. Insurers and roofers alike will ask when you first noticed the damp and what the conditions were. A clear timeline helps.
When water is getting in through your roof, the instinct to do something immediately is understandable. Some of those instincts will make the problem worse, or put you in danger.
Do not go onto the roof. This is the most important point. Pitched roofs are slippery even in dry conditions and working on one without proper equipment and training is genuinely dangerous. Every year people are seriously injured - or worse - falling from domestic roofs. Lead work in particular is located around chimneys and at valleys, both of which require working near a ridge or on a slope. A professional will use scaffolding, access equipment and fall protection. You should not attempt to replicate that with a ladder and determination.
Do not apply sealant or mastic over a flashing. Roof repair sealant in a tube is sold at every builders' merchant and seems like a quick fix. In practice, applying mastic over a failed flashing almost always causes more problems than it solves. Sealant applied over a damp or dirty surface does not bond properly and will peel away, often taking the flashing with it. It also masks the underlying problem, meaning that when a roofer eventually inspects the area, the true extent of the failure - and sometimes additional damage underneath - is hidden. Lead cannot be properly re-dressed over old mastic; it has to be stripped back and the area cleaned before new lead can be fitted. You may be adding cost and complexity to what would otherwise be a straightforward job.
Do not attempt to repoint a chimney from a ladder. Repointing a chimney properly requires reaching all four sides of the stack, working at height and mixing mortar correctly for the application. Applying a blob of ready-mix mortar to a joint you can just reach from a top-rung ladder position is unlikely to achieve a proper bond and is likely to result in a fall hazard. Chimney pointing is a job that requires scaffolding or a cherry picker, not a DIY ladder job.
Do not use expanding foam. Foam applied in a roof void to try to block a water path through the structure is occasionally done in desperation and almost always causes additional problems. It can trap moisture, cause timber rot, void ventilation paths and make future repairs significantly harder. It does not address the source of the leak.
Do not ignore a small leak. A damp patch that appears after heavy rain and dries out can seem manageable. Left unattended, water working through a failed flashing causes timber rot in the roof structure, damaged insulation, mould growth in the ceiling void, and eventually plaster failure and damage to decorations and contents. A small lead repair carried out promptly is almost always significantly less expensive than the cumulative cost of the internal damage a slow leak causes over one or two winters.
When a roofer carries out a proper lead job - rather than a temporary patch - the work follows a clear sequence. The old lead and any failed mortar pointing is stripped back completely. The underlying surfaces, whether brick, tile or decking, are checked for damage and repaired if necessary before any new material goes on.
New lead sheet of the correct code is cut to the dimensions of each section. Chisel dressing tools are used to work the lead into shape so it sits tight against every surface without relying on sealant to fill gaps. Movement clips are fixed at the correct spacing so the lead can expand and contract without pulling away from its fixings. Overlaps between sections are sized correctly - typically a minimum of 75mm for flashings and more for valley sections - so that water cannot track uphill under the joint.
At chimneys, the top edge of the flashing is tucked into a mortar joint and secured with lead wedges, then pointed with a mortar mix appropriate to the brickwork. Some roofers use sealant to point a flashing chase rather than mortar - this is generally considered less durable and not the correct approach for a long-term repair.
At the end of the job, all debris - old lead, mortar, tile offcuts - should be cleared from the roof and gutters. Old lead has scrap value and is usually taken away by the roofer.
Lead work pricing depends on the type and scale of the job. As a general guide, chimney flashing repairs on a typical semi-detached or detached house typically cost between £300 and £800, depending on the number of sides involved and whether the pointing also needs attention. A full lead valley replacement on a pitched roof typically costs £400 to £900 for a standard domestic valley. Flat lead roofs over bays or porches are usually priced by the square metre; a typical bay top might cost £600 to £1,200 depending on size and access.
Scaffold costs are separate from the lead work itself when a scaffold is required. A chimney flashing repair on a two-storey house will almost always need scaffold, and this adds £300 to £600 in most cases. Some roofers include scaffold in their overall price; it is worth asking when you get a quote.
Lead is a commodity and its price fluctuates. Quotes given several weeks apart may differ for this reason alone.
Before agreeing to any lead work, ask the roofer what code of lead they intend to use and why. Ask whether the existing lead will be fully stripped or whether they plan to work over it. Ask what will happen to the old lead. Ask whether the pointing will be done in mortar or sealant. These are not trick questions - any experienced lead worker will answer them readily and will have clear reasons for their choices.
If a quote seems very low, it is worth asking whether it includes scaffold where scaffold is needed, and whether it covers the cost of the lead at current prices. A price that looks attractive but does not include these elements may not be the most economical choice once the full cost is clear.
We carry out lead work in North Walsham and travel to neighbouring towns and villages across the area, including Aylsham and other communities within reach of our Norwich base. For any lead flashing repair, valley lining, chimney work or flat lead roof on a bay or porch, call us to arrange a survey and a clear quote before any work begins.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
