When lead work fails on a Tuddenham property, the signs are rarely obvious until water has already found its way in - knowing what to look for early can save you a costly repair bill.
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Lead is used in several places on a roof, and each application has its own demands. Flashings seal the joint between a roof slope and a vertical surface - a chimney, a parapet wall, a dormer, or a soil pipe. Lead valleys channel rainwater down between two roof slopes. Step flashings work their way up a chimney course by course. Soakers slip under each course of slates or tiles alongside a chimney or abutment. And on some flat roofs, lead forms the weathering surface itself.
Each of these details is hand-dressed on site, shaped to the exact profile of the masonry or timber beneath it. No two jobs are identical because no two chimneys or roof junctions are built exactly the same way. That is why lead work is one of the more skilled trades within roofing - a roofer who handles it well has put in years of practice before they reach a high standard.
All lead work should be installed to the correct Code. The Code of lead refers to its thickness - Code 3 is thinner and suited to soakers and internal gutters, Code 4 is the most common specification for flashings, and Code 5 or 6 is used for valleys and flat roof areas where the sheet needs to carry more water or resist greater movement. Using the wrong Code for the application is a common cause of early failure.
Lead is a long-lasting material when it is installed correctly and maintained. But it does fail, and when it does, the roof becomes vulnerable to water penetration at the very points that are hardest to waterproof with any other material. Knowing the warning signs means you can act before the damage spreads.
Damp patches on a chimney breast or ceiling near a chimney. This is one of the most telling signs. If you notice a damp patch appearing on an interior wall or ceiling close to where a chimney passes through the roof, the flashing around that chimney is the first thing to investigate. Water does not always travel straight down - it can run along a rafter or joist before appearing in a different spot to where it entered, so a damp patch a metre away from the chimney stack can still be caused by flashing failure.
Lifting or pulling-away lead. Stand back and look at your chimney or dormer. Lead that has separated from the masonry or that is curling upward at the edges is no longer sealing the joint. This can happen because the lead was not properly fixed into a mortar joint, because the mortar joint itself has failed, or because the lead has expanded and contracted over many seasons without enough room to move.
Cracked or missing mortar where lead meets brickwork. Lead step and cover flashings are tucked into a raked mortar joint and fixed with lead wedges before the joint is pointed up. Over time, mortar shrinks, cracks and falls out. When the pointing goes, the top edge of the flashing is exposed to water running behind it. This particular failure is very common on older chimney stacks where the mortar is lime-based and has gradually weathered away.
Splits or cracks in the lead itself. Lead expands and contracts with temperature. If sheets are cut too long and not given adequate roll joints or drips to accommodate thermal movement, the metal fatigues and cracks over time. A cracked lead valley or flat roof lead sheet will leak steadily in rain and is not repairable with sealant - the damaged section needs to be replaced.
Discolouration or white streaking on brickwork. A white chalky stain running down a chimney from the flashing line is a sign that water has been tracking behind the lead for some time. The streaking is caused by salts leaching out of wet mortar. It tells you the leak has been ongoing, not a recent event.
Interior mould or musty smell in a loft or top-floor room. Persistent low-level leaks through failing lead work often do not produce obvious drips. Instead, they introduce moisture slowly into roof timbers and insulation. A musty smell in a loft, or mould appearing on rafters or on the underside of roof boarding, is worth investigating. A roofer checking the lead details is a sensible first step before assuming the problem is elsewhere.
Understanding why lead work fails helps you ask the right questions before work is carried out, and helps you assess the quality of what you are being quoted for.
Poor original installation. Lead installed by someone without proper experience in the trade is the single biggest cause of early failure. Common errors include using lead that is too thin for the application, failing to dress the lead tightly into mortar joints, leaving insufficient overlap between flashings, and not allowing for thermal movement with correct jointing. A flashing that looks presentable from the ground can still be technically inadequate.
Thermal movement not accounted for. Lead moves. On a warm day, a lead sheet heats up and expands; on a cold night, it contracts. If a sheet is fixed rigidly over too great a length without a roll joint or expansion joint to absorb the movement, the repeated stress causes fatigue cracking over several years. Lead sheets in valleys and on flat roofs should not exceed around 1.5 metres in length without a proper drip or roll joint to manage this movement.
Mortar failure. The mortar that holds flashing joints into brickwork has a limited lifespan, particularly in older lime mortar joints. As it weathers, it recedes and eventually falls out, leaving the top edge of the flashing open to water. Re-pointing the mortar joints around flashings is a maintenance job that should be done before the joint is fully open.
Incorrect Code specification. Code 3 lead is sometimes used where Code 4 or 5 is the correct choice. Thinner lead is cheaper, but it is less durable and more susceptible to thermal fatigue. Specifying the correct Code for each application is not optional - it is part of doing the job properly.
Incompatible sealants applied over lead. A very common bodge repair is to apply bitumen or silicone sealant over a failing lead joint. This delays the problem very briefly and then makes it worse, because sealant prevents the lead from moving naturally, concentrating stress at one point and accelerating cracking. It also makes the underlying problem harder to assess. If you can see sealant over lead on your roof, the lead beneath it needs to be properly inspected.
Age and natural wear. Lead is not immortal. Properly installed Code 4 flashings on a well-maintained chimney can last 50 to 80 years, but that lifespan depends on the installation quality and maintenance history. On roofs where the original lead has never been replaced, it may simply have reached the end of its serviceable life.
When a roofer assesses failing lead work, the first decision is whether the existing lead can be repaired or whether it needs to be replaced. Minor issues - a single cracked section, a failing mortar joint, a piece of lead that has pulled away but is otherwise sound - can sometimes be addressed without a full replacement. In most cases, though, where lead has failed in one area, other sections of the same installation are likely to be close to failure as well. Replacing everything in one visit is usually more economical than returning in 18 months to deal with the next section.
Replacing chimney flashings typically involves stripping all the existing lead from around the chimney, raking out the mortar joints to create a clean chase to tuck new flashing into, cutting and dressing new lead sheets to the correct profile, fixing them with lead clips or wedges into the raked joints, and then pointing up with an appropriate mortar. On a straightforward chimney on a standard pitched roof, this is a day's work for an experienced roofer.
Valley replacement is a larger job. The tiles or slates on either side of the valley need to be lifted, the old lead or felt valley stripped out, and new lead laid in sections with proper lapped and dressed joints. The slates or tiles are then relaid and re-bedded as needed. The cost and time depend on the length of the valley and the type of roof covering alongside it.
Flat roof lead work - typically a lead-clad flat roof or a lead gutter - is more material-intensive and requires careful attention to drips and rolls to manage drainage and movement correctly.
A lead work job done properly should leave no exposed fixings, no sealant used as a primary weathering detail, and no section of lead that is rigid over more than about 1.5 metres without a movement joint. The mortar pointing at flashing joints should be neat and fully filled. On a chimney stack, the back gutter behind the chimney is just as important as the side flashings - if water pools behind the stack and there is no proper dressed back gutter, leaks will continue even after the side flashings are replaced.
Ask your roofer what Code of lead they are specifying for each part of the job, and why. A competent roofer will be able to explain the choice. Ask whether they are replacing all the lead on the chimney or just the section that has obviously failed. Ask what they will do with the mortar joints - whether they are being raked out and properly re-pointed, or just filled over.
The cost of lead work in Suffolk typically ranges from around £300 to £600 for a straightforward chimney flashing replacement on a standard semi-detached or terraced property, rising to £800 or more for a larger or more complex chimney stack with a back gutter and step flashings on both sides. Valley replacement costs depend heavily on the length and the roof covering, but a typical single valley in lead might cost £600 to £1,200 or more depending on access and whether scaffolding is required.
We carry out lead flashing, valley, and flat roof lead work in Tuddenham and across the surrounding area, including Mildenhall and neighbouring villages. If you have noticed any of the warning signs described above - damp patches near a chimney, lifting lead, cracked mortar at flashing joints, or staining on brickwork - call us and we will come out to assess the lead work and give you a clear picture of what needs to be done and why.
Getting to the cause of a leak early is nearly always cheaper than dealing with the water damage that follows if it is left.
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