If you have a roof leak near a chimney, skylight or valley in Dereham, failed lead work is the most likely cause - and understanding what the job will cost helps you plan properly.
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Lead flashing is the folded and dressed sheet metal that seals every junction on your roof - where the roof slope meets a chimney stack, where a dormer joins the main roof, where slates or tiles abut a parapet wall, and in the valleys where two roof slopes meet. Without properly fitted lead, rainwater forces its way into the gap between the masonry and the roofing material, and once that happens you get damp on internal ceilings, rotting timbers and, eventually, structural damage.
Lead has been used on British roofs for centuries because it is soft enough to be worked by hand, expands and contracts with temperature without cracking, and lasts far longer than any modern substitute when fitted correctly. A well-dressed lead flashing on a chimney can remain weathertight for fifty years or more. Poorly fitted lead, on the other hand, can fail within a few years - and the damage it causes is always more expensive than the original job would have been.
Lead work should be carried out to traditional hand-dressed standards - step flashings, cover flashings, soakers, back gutters, valley linings and flat roof coverings. Every piece of lead sheet is selected by the correct BS code for its location and purpose. Code 3 and Code 4 are typical for flashings and soakers; Code 4 and Code 5 for valleys; heavier codes for flat roof sections. Getting the code right matters because underweight lead moves too much with thermal expansion and splits at the folds over time.
Chimney flashings are the single most frequent source of roof leaks. A chimney stack projects through the roof plane on all four sides, which means it needs step flashings up the pitched sides, a back gutter behind it and a cover flashing at the front. A common problem is that one section is re-bedded in mortar when it lifts, rather than the whole system being inspected. Mortar alone cannot hold flashing long-term - the lead needs to be properly dressed into a raked joint in the brickwork and fixed with lead wedges, with the joint then pointed in a flexible sealant or sand-and-cement mortar.
Valley gutters are another frequent failure point. An open lead valley channels water from two converging roof slopes down to the eaves. When the lead splits - usually at a lap joint or a fold - water tracks beneath the surrounding slates or tiles invisibly, often for months before the ceiling stain appears. By then, the underlying timber valley board can be saturated. Replacing a failed valley means lifting the surrounding slates, cutting back to sound material, fitting new valley boards if needed, and laying new lead to the correct code and lap dimensions.
Flat roofs covered in lead are less common on modern homes but still appear on older properties. The lead on these sections is often original and, if the sections were not weighted or the falls were never properly formed, can pond water and eventually crack. Repairs are sometimes possible; a full re-lead is the correct solution when the sheet is pitted or has multiple cracks.
Soakers are small individual lead pieces that sit under each course of slates or plain tiles at an abutment wall - the junction between a roof slope and a brick wall, for example beside a chimney or where a lean-to joins a house. A common problem is that soakers were never fitted at all and the original builder relied on mortar-bedded flashing alone. When the mortar cracks, there is nothing behind it. The fix requires lifting the slates, fitting correctly sized soakers under each course, and then re-dressing the cover flashing over the top.
Cost is the angle most homeowners want clarity on before they call anyone, so here is a straightforward breakdown based on typical current UK rates. These figures reflect the cost of the work itself - materials and labour - for a competent tradesperson working to correct standards. Prices vary depending on access, the condition of the surrounding roof structure and whether any timber repairs are needed alongside the leadwork.
A full chimney re-flash - step flashings, cover flashing and back gutter - on an average two-bedroom semi typically costs in the region of £400 to £900. A small chimney on a single-storey extension at the lower end; a large double stack on a detached house at the higher end. The range reflects the difference in the amount of lead needed, the complexity of the work and the height of the stack above the roof level.
Partial repairs - re-dressing a lifted cover flashing or re-pointing a stepped joint - are cheaper, but only worthwhile if the rest of the system is genuinely sound. If the surrounding lead is tired, patching buys limited time.
Replacing a lead valley on a typical pitched roof costs roughly £350 to £800 for a short run, rising to £1,200 or more for a longer valley or one where the timber valley board has deteriorated and needs replacement. The slates or tiles lifted to access the valley need to be re-fixed carefully - good roofers keep them sorted and numbered so the pattern is matched. Any that are broken during lifting need replacing, which adds to the final figure.
Fitting soakers and a cover flashing at a standard abutment - a lean-to roof meeting a house wall, for example - costs roughly £300 to £600 depending on the run length and access. If soakers were never fitted originally, the cover flashing alone cannot keep water out long-term, so the full job is necessary even if it costs more upfront.
Lead on a flat surface - a bay window top, a porch or a small flat roof - is priced per square metre. Typical rates for supply and installation of code-appropriate lead sheet on a flat section run from around £150 to £250 per square metre, depending on code weight, the complexity of the falls and the condition of the decking below. A standard bay window top of around 2 square metres might therefore cost £300 to £500 before any structural repairs to the boarding.
The process matters as much as the price. When a roofer quotes for a chimney re-flash, the correct approach starts with removing all of the existing lead, not just the section that has visibly lifted. Chasing out the mortar joints in the brickwork, dressing new step flashings individually from flat sheet, fixing them with lead wedges and then pointing with an appropriate mortar or sealant. Each step flashing should lap the one below by at least 65mm. The cover flashing should be set at least 25mm into the raked joint and turned down to lap the step flashings by at least 150mm.
For valleys, the lead should be laid in manageable lengths - generally no more than 1.5 metres per piece - with a proper lap joint so thermal movement does not cause buckling or splitting. The lead should be secured with clips, not nails driven through it, as nail holes are a future leak waiting to happen.
Flat lead sections need properly formed falls to shed water - a minimum fall of 1:60 is the standard recommendation. Lead should be fixed at one edge only to allow movement, and bossed or welted at corners rather than cut and overlapped without proper joints.
Ask any roofer quoting for lead work what code of lead they intend to use and where the sheet will come from. A legitimate supplier and the correct BS code for each location are both signs that the job will be done to a standard that lasts.
Lead work is a skilled trade that takes time to learn properly. It is not something that can be taught in an afternoon, and the difference between a hand-dressed flashing that lasts decades and one that lifts within a year is entirely down to the care taken with each individual fold, welt and chase.
When comparing quotes, check whether the price includes removing all existing lead or just fitting over the top. Re-leading over old, failed sheet is not an acceptable approach - the old material needs to come off so the substrate can be inspected properly. Check also whether any timber repairs are included or quoted separately, and whether the scaffold cost is included or an addition.
A low quote that assumes good access and no timber damage can quickly become expensive if those assumptions turn out to be wrong. A detailed quote that sets out what happens if the valley board needs replacing, or if the chimney brickwork requires pointing, is more useful than a headline figure that excludes every possible extra.
Lead work rarely sits entirely on its own. A chimney that needs re-flashing may also need re-pointing or have loose pots that need re-bedding. A valley replacement often exposes slipped or broken slates in the surrounding area. It makes sense to address these at the same time rather than returning to the same section of roof in twelve months.
We work across Norwich and the surrounding area, including Dereham and nearby towns and villages throughout Norfolk. If you have a suspected lead work failure - a damp patch on a ceiling near a chimney breast, staining on a wall beside a lean-to, or water tracking into a loft after rain - call us to arrange a roof survey. We will inspect the lead work, explain what we find in plain terms, and give you a clear picture of what needs doing and what it is likely to cost before any work starts.
If the lead itself is in reasonable condition and has simply lifted from the joint, it can sometimes be re-fixed and re-pointed without full replacement. If the lead is cracked, pitted, has been patched repeatedly or is the wrong thickness for the location, replacement is the right answer. A roofer should be able to tell you which applies after a proper visual inspection from close up, not from the ground.
A well-maintained roof in good condition - including properly dressed lead flashings - is something buyers and surveyors look for. A surveyor noting failed flashings or evidence of water ingress is likely to flag it as a defect, which can affect a sale price or become a renegotiation point. Getting lead work done before putting a house on the market removes that risk. It will not add dramatic value on its own, but failing lead work actively reduces it.
Small re-pointing jobs at accessible locations are sometimes tackled by homeowners using flexible roofing sealant, but this is a temporary measure, not a repair. Dressing lead correctly requires tools - a bossing mallet, dresser and chase wedges - and the skill to form weathertight joints without cracking the lead. An incorrectly dressed joint often makes the problem worse by channelling water in a new direction. For anything beyond pushing a slightly lifted flashing back into place, a roofer is the safer choice.
Correctly specified and hand-dressed lead flashings can last fifty years or more. Lead valley linings on properly maintained roofs frequently outlast the surrounding slates. Flat lead sections on bays and porches, where the sheet may be thinner or the falls poorly formed, sometimes fail sooner. The key factors are the correct lead code for the location, proper jointing to allow thermal movement, and a sound substrate beneath.
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