If you have a leak around a chimney, valley or parapet in Swaffham, failed lead flashing is the most likely cause - and getting the lead work done properly is what stops it happening again.
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Lead is the material roofers have used for centuries to seal the joints where a roof meets a wall, chimney, skylight or another roof slope. It forms a flexible, weathertight barrier that moves with the building through heat and cold without cracking. When it is properly dressed and fixed, it outlasts almost every other roofing material around it.
The main types of lead work on a typical house are step and cover flashings around chimneys, soakers tucked under each course of slates or tiles where a roof meets a side wall, valley linings that channel rainwater down the angle between two roof slopes, and flat roof coverings or bay top coverings where lead is used as the primary weatherproofing layer. Each of these is a distinct task requiring different lead codes and different fixing methods.
Lead is graded by thickness, described as a code number. Code 3 is the lightest, used for soakers. Code 4 is the everyday standard for most flashings. Code 5 and above is used for valleys, flat roof sections and any area carrying a significant volume of water. Using the wrong code is one of the most common reasons why lead work fails prematurely, and it is something worth asking about before any job begins.
Understanding what a lead work job actually involves, step by step, helps you know what to expect and makes it much easier to spot whether the work being carried out is thorough or corners are being cut. Here is how a properly done lead job runs from start to finish.
Before any lead is touched, the area needs a proper look. That means getting close enough to see what is actually there - not just a view from the ground with binoculars. The roofer should check the existing lead for cracking, lifting, poor laps, failed mortar pointing, and whether the lead has been correctly stepped and wedged into the masonry joints.
A common problem is lead that has been over-dressed in one piece rather than in correctly sized bays. Lead expands and contracts significantly with temperature changes. Bays longer than roughly 1.5 metres will ripple, buckle and eventually crack at the stress points. A good inspection will identify whether this is what caused the original failure.
The roofer should also check the tiles or slates immediately around the lead. Sometimes the lead itself is not the leak source - a cracked or slipped tile nearby is letting water in. Getting that right before the lead is replaced saves a return visit.
Access has to be right before the work begins. On most houses that means a scaffold tower or a properly footed ladder, depending on the pitch and height involved. For chimney work above a two-storey house, scaffold is the correct approach - both for safety and because you cannot do careful, accurate lead dressing while balancing on a ladder.
The area below the working zone should be cleared or protected. Lead offcuts, old mortar and tile fragments will fall during a strip-out. A decent roofer will lay boards or tarpaulins to protect paths, drives and planted borders before starting.
The failed lead comes off first. On a chimney stack, that means removing the flashing in sections, clearing the mortar from the raggle (the groove cut or raked into the mortar joints), and checking the condition of the brick or stonework beneath. If the raggle has been filled with modern sealant rather than properly cut and pointed, that sealant needs to come out completely - sealant on its own is not a substitute for proper lead fixings.
On a valley, stripping out means lifting the tiles or slates on either side of the valley, removing the old lining, and checking the valley boards and any underlying felt for rot or damage. Replacing a valley liner over rotten boards is a waste of time and money - the boards should be replaced at the same time.
For soakers, each soaker sits under an individual slate or tile and tucks against the adjacent wall. Replacing them means lifting those slates or tiles one by one, removing the old soakers, and setting them aside carefully for re-use if they are undamaged.
Clean, stable substrate is what makes lead work last. For chimney flashings, that means clearing the raggle joints fully, brushing out loose mortar and dust, and checking that the brickwork itself is sound. Spalled or loose bricks should be pointed before the new lead goes in - otherwise water will track through the brickwork even if the flashing is perfect.
For valley work, new timber boards should be fitted where needed, and any tears or gaps in the underlay beneath should be patched. The valley board surface should be smooth and even so the lead lies flat without bridging over any gaps.
This is the skilled part of the job. Lead sheet comes in rolls and is cut to size using a knife or shears, then dressed by hand using a bossing mallet and wooden dresser. It cannot simply be bent flat against a surface - it has to be worked carefully to form tight corners, neat laps and correctly formed upstands without splitting or thinning the material.
Each bay of flashing is cut to no more than 1.5 metres in length with an expansion gap of around 10mm between bays. This is not optional - it is what stops the lead from buckling and cracking over time. The bays overlap correctly so water cannot track back between them.
Lead wedges or clips are used to secure the top edge into the raggle joint. The wedges are cut from off-cuts of lead and driven into the mortar joint at regular intervals - roughly every 450mm - before the joint is repointed. Fixings should not show on the face of the finished work.
For valleys, the lead is dressed over the boards and turned up at the edges beneath the tiles to form a proper upstand. The width of the exposed lead gutter in the valley depends on the pitch of the roof - the shallower the pitch, the wider the valley needs to be. A valley on a low-pitched roof running too narrow is a common reason for water overshooting in heavy rain.
Once the lead is fixed and dressed, the raggle joints are repointed with mortar. The mix matters - modern cement-heavy mixes are inflexible and tend to crack away within a few years as the lead moves. A slightly weaker, more workable mix bonds better and lasts longer in this application.
Where the bottom edge of the flashing sits against a horizontal surface, such as a flat roof or a parapet coping, it is dressed down and the arris (the bottom edge) is turned slightly to prevent water tracking back behind it by capillary action.
Any tiles or slates lifted during the job go back in the correct order and correctly fixed. If any were damaged during the strip-out, they should be replaced with matching material. This matters - a mismatched tile on a clay or slate roof stands out clearly, and on an older property it can also affect planning considerations if the property is listed or in a conservation area.
The roof covering around the new lead should be checked and any loose or lifted fixings put right while access is already in place. It makes no sense to leave a potentially loose tile adjacent to new flashing work.
All off-cuts, old lead, broken tile fragments and mortar debris come off the roof and are cleared from the area below before the roofer leaves. Old lead is a recyclable material and any responsible roofer will either take it away or leave it for you to dispose of as you prefer - scrap lead has a realisable value.
A final check from below and, where practical, from the access equipment confirms the flashing is sitting flush, the pointing is filled and neat, and there are no obvious gaps or lifted sections. If the work involved a chimney, the visual check should include the flaunching (the sloped mortar cap around the chimney pot base) - this is often in poor condition on chimneys where the flashing has failed, and attending to it at the same time avoids a separate visit later.
Most lead flashing failures come down to one of four causes: lead cut too short so the upstand is too low to stop water overtopping it in heavy rain; bays cut too long so the lead buckles and cracks; poor fixing into the raggle so wind lifts the flashing over time; or mortar pointing that has shrunk away and left a gap at the top edge.
A straightforward chimney flashing repair on a standard two-storey house in and around Swaffham typically costs in the region of £250 to £600, depending on the size of the stack, the number of sides to be flashed and how much of the existing lead can be reused. A full strip and re-lead of a chimney stack is usually £400 to £900. Valley re-lining costs vary considerably with the length of the valley - roughly £80 to £150 per linear metre is a realistic range. Flat roof lead coverings on a bay or porch typically run from £500 to £1,500 depending on the area involved.
These are typical current UK figures and are a starting point for comparison, not fixed prices. The only way to get an accurate cost is to have the job looked at properly.
A dripping ceiling or a damp patch on a top-floor wall does not always point directly to the obvious candidate. Water travels before it drops, and the entry point can be some distance from where you first see the damp. A leak appearing near a chimney breast is very likely to be flashing-related, but a leak at an internal corner of a dormer or extension can come from failed soakers, a cracked tile or a blocked gutter causing water to back up under the eaves.
Getting the diagnosis right before stripping out lead is important. Replacing a chimney flashing when the actual leak is a cracked ridge tile two metres away is frustrating and expensive. Any reputable roofer will look at the whole area around a reported leak, not just quote for the most visible piece of lead work.
Old lead does not always need full replacement. Lead that is still correctly secured and the right code, but has a small split or a section of failed pointing, can often be repaired by cleaning back the area, fitting a patch and re-pointing the joint. This is a legitimate approach and considerably cheaper than a full strip and re-lead.
However, lead that is heavily fatigued - showing multiple cracks, significant corrosion or extensive buckling - is better replaced fully. Patching fatigued lead buys limited time. On a roof where the lead is original to a house built more than 60 or 70 years ago, the material may have given good service but simply be at the end of its useful life.
The roofer's recommendation should include a clear explanation of why repair is or is not the right call. If you are told the whole lot needs replacing on a roof where sections look visually fine, asking why those sections cannot be retained is a reasonable question.
These are not awkward questions - they are the basics of what a properly priced lead work job should include. Any experienced roofer will be happy to answer them before work starts.
Norwich Roofers carries out lead work across Swaffham and the wider Norfolk area. We cover the full range of lead work tasks - chimney flashings, step and cover flashings, soakers, valley linings and flat roof lead coverings - using code-appropriate lead sheet and traditional hand-dressing techniques.
If you are unsure whether we cover your area, call and ask - it is a straightforward question.
If you have a leak you think is related to failed lead work, or you want a proper look at lead flashing that is showing signs of age, call us to arrange a roof survey. We will inspect, explain what we find and give you a straight answer on what needs doing and what it will cost.
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Call any time. Calls are answered day and night and passed straight to our roofers.
