If you can see damp patches, cracked mortar or stained ceilings near a chimney or roof junction, failing lead work in Burwell could be the cause.
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Lead is used wherever a roof meets a vertical surface - chimneys, dormer walls, parapet walls, soil pipes and roof-to-wall abutments. It is also used in valleys, where two roof slopes meet, and occasionally as a flat roof covering on smaller areas. Its job is to create a watertight seal at these junctions, which are the points most vulnerable to water ingress on any roof.
When lead work is in good condition and properly installed, it will outlast most other roofing materials by decades. When it fails - or was badly fitted in the first place - water gets in silently and the damage can be well advanced before you notice anything inside the property.
We carry out lead flashing, valley work and flat roof lead work in Burwell and the surrounding area. All lead is dressed by hand to the correct Code specification and fixed properly into the masonry or substrate beneath.
This is the angle most homeowners need to understand, because lead work fails gradually and the signs are easy to misread or ignore. Knowing what to look for - and what is causing it - means you can act before the damage becomes expensive.
A damp patch appearing on a ceiling or upper wall, particularly close to a chimney breast, is one of the most reliable indicators of flashing failure. The water is not necessarily entering directly above the stain - it may be tracking along a rafter or ceiling joist from a point several feet away. If the damp appears after rain and dries out in dry weather, lead work is a strong candidate.
What is usually happening: the flashing has lifted at one edge, the mortar pointing that holds the flashing into the raggle joint has cracked and fallen away, or the lead itself has split. Water then runs down behind the flashing rather than over it.
Look at the line where lead flashing meets a chimney stack or wall. The top edge of the flashing is tucked into a cut groove (the raggle) in the mortar course and then pointed over. Over time, this pointing cracks, shrinks and drops out. Once it goes, the top edge of the flashing is open and water runs straight in behind it.
This is a common problem on older properties where the original pointing has simply reached the end of its life. It is also seen on chimneys where thermal movement has been significant - a tall brick stack expands and contracts with temperature changes, and if the flashing is not dressed correctly, it pulls the pointing apart over years of movement.
Lead is a soft metal and it moves with temperature. In summer it expands; in winter it contracts. If a piece of lead is too long, or was not given enough room to move when it was installed, it will split or crack over time. This is called fatigue cracking, and it is almost always a sign of incorrect installation rather than poor-quality material.
Correctly installed lead flashings are cut into individual sections no longer than 1.5 metres, with small gaps between each piece to allow movement. If a previous roofer ran one long piece up a full chimney face, fatigue cracking is inevitable. You may be able to see this from the ground with binoculars - look for hairline cracks running across the face of the lead, particularly on south-facing elevations where thermal movement is greatest.
Dark streaking or green algae growth on brickwork below a roof valley or parapet wall can indicate that water is escaping from a valley gutter or that a parapet lead gutter is overflowing or leaking through a joint. Lead valley gutters accumulate debris - moss, leaves, grit - and if the outlet is blocked the water backs up and eventually finds a way through.
A lead valley that has been patched repeatedly with bitumen sealant is also a warning sign. Bitumen patches are a short-term fix that rarely last more than a season or two. If you can see black patches on a valley from the ground, the valley probably needs relining rather than patching again.
Before a leak becomes visible on a ceiling, it often shows up as a musty smell in the loft. If you go up into your loft after a period of heavy rain and notice dampness on the timbers around the chimney stack or at the gable ends, that is worth investigating before it becomes a ceiling stain. Wet timbers that stay wet will eventually rot, which is a far more expensive repair than the lead work that caused it.
Understanding why lead fails helps you judge whether a repair will hold or whether a full replacement is the right answer.
A significant proportion of lead work failures come down to how it was put in originally. Common installation errors include: lead dressed too thinly (too low a Code number for the application), single long runs without expansion joints, insufficient overlap between the flashing and the roof tiles or slates beneath, and pointing that was done with the wrong mortar mix. These problems may not become obvious for several years, but they will eventually surface.
The Lead Sheet Association publishes guidance on Code weights, lap dimensions and fixing methods, and a competent roofer will follow these. Code 3 lead (1.32mm thick) is the minimum for flashings; Code 4 (1.80mm) or Code 5 (2.24mm) is used for heavier applications such as valleys and flat areas. Using the correct Code for each application is not optional - it directly affects how long the work will last.
Even correctly installed lead has a finite lifespan, though that lifespan is long - typically 50 to 70 years for well-installed flashings, and 100 years or more in some cases. As lead ages, it becomes harder and less ductile, which means it is more prone to cracking under thermal stress. Old lead on a Victorian or Edwardian property may simply have reached the point where repair is no longer sensible and full replacement is the right call.
Chimney stacks settle and move independently of the main roof structure. Even small amounts of differential movement - a few millimetres over years - can pull flashings away from the masonry. If a stack has been repointed without attention to the flashings, or if the chimney itself has been taken down and rebuilt, the lead work around it needs to be checked and often redone.
Bitumen sealant, lap tape and silicone are not permanent solutions for failing lead. They may stop an immediate drip, but they do not address the underlying cause, and they can make a proper repair more difficult later - particularly if sealant is worked into the raggle joint, which then has to be raked out before new pointing can be done. If your lead work has been patched before, ask what was used and where, so the next roofer understands what they are working with.
A chimney typically requires four separate components: the front apron (at the base of the front face), the two side step flashings (which step up with the roof slope), the back gutter (which collects water running down the back face) and soakers (individual pieces of lead that sit under each tile or slate course). All of these need to be dressed correctly and in sequence for the system to work. Replacing just one component without checking the others is a common cause of a leak recurring after a repair.
Lead valleys are used where two roof slopes meet. They are a more durable alternative to mortar-bedded tiles or pre-formed valley troughs, and they look better on period properties. A lead valley is formed from dressed lead sheet laid into a timber valley board, with the edges dressed under the adjacent tiles or slates on either side. The minimum width of exposed lead in a valley gutter is 100mm for a roof pitch of 30 degrees or more - this gives enough width to carry water without backing up under the tiles in heavy rain.
Where a roof slope meets a wall - such as a side extension roof butting against a two-storey wall - step and cover flashings are needed. The step flashing pieces are worked into the mortar courses of the brickwork and overlap the tiles below; the cover flashing laps over the top of the step flashing. Getting the overlap right matters: the cover flashing should lap the step flashing by at least 75mm to prevent wind-driven rain getting behind it.
Lead is one of the traditional materials for small flat roof areas - bay tops, dormers, outhouse roofs. For flat or near-flat applications, Code 6 or Code 7 lead is typically used, as the extra thickness provides the rigidity and durability these exposed areas need. Bossing or welding at corners and upstands requires genuine skill - a poor corner joint is a guaranteed leak point. We dress all lead by hand to ensure proper seating and waterproofing at every junction.
If you are getting quotes for lead work, it helps to know what a thorough job should include so you can judge what you are being offered.
If a quote does not make clear what is being removed and replaced, ask. A price that seems very low may reflect lead being patched rather than replaced, or a lighter Code being used than the job requires.
Lead work is priced by the job rather than by a simple square metre rate, because the complexity of dressing, the amount of preparation and the type of junction all affect the time involved. As a general guide, a full chimney flashing replacement on a standard semi-detached property typically costs in the range of £400 to £900 depending on the size of the stack and the number of components involved. A lead valley relining might run from £600 to £1,500 or more for a longer valley. Smaller repairs - replacing a section of cracked flashing or repointing a raggle - will cost considerably less.
These are typical current UK figures. The actual cost for your property will depend on access, the condition of the existing work and what preparation is needed. Any quote should specify what is being done, what materials are being used and what the price includes.
This is the key question for most homeowners. A repair is appropriate when the lead itself is in good condition - correct Code, no fatigue cracking - and the problem is limited to failed pointing or a single lifted section. A replacement is more appropriate when the lead is thin, cracked across multiple sections, has been heavily patched, or is simply old enough that further deterioration is predictable within a few years.
Getting a replacement done properly once is nearly always better value than paying for repeated repairs on lead that is past its useful life. Ask any roofer who quotes for a repair to tell you honestly what condition the surrounding lead is in and how long they expect the repair to hold.
If you have noticed any of the warning signs described above - damp patches, cracked mortar, stained ceilings or a musty loft - call us to arrange a roof survey. We will inspect the lead work and tell you exactly what the problem is, what needs doing and what it will cost. There is no obligation and no pressure. Call Mildenhall Roofers today to book your survey.
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