If you have a roof leak near a chimney, dormer or valley in Aylsham, failed lead work is the most likely cause - and catching it early saves a great deal of money.
Lead is the material used to seal the joints where your roof meets a vertical surface - a chimney stack, a dormer wall, a parapet, a skylight kerb, or a change in roof pitch. Water will always find the lowest point, and those junctions are exactly where it tries to get in. A correctly fitted lead flashing directs rainwater away from that joint and out over the tiles or slates below.
The lead work on a roof takes several forms. Step flashings and cover flashings seal around chimney stacks. Soakers are small interlocking pieces of lead tucked beneath each individual slate or tile where a roof meets a wall. Valley gutters channel water running down from two converging roof slopes. Flat roofs, box gutters and parapet gutters can also be covered in lead sheet where the fall and detailing call for it. Each type is cut and dressed by hand on site to fit the exact geometry of your roof.
Lead is a traditional roofing material because it works. It is malleable enough to be shaped tightly into angles and stepped profiles, it expands and contracts with temperature changes without cracking, and when fitted properly it outlasts most other roofing materials by a considerable margin. The problems come when the lead was not fitted correctly in the first place, or when an older installation has eventually reached the end of its useful life.
This is where most homeowners get caught out: the symptoms of failed lead flashing often appear somewhere other than directly above the leak. Water entering at a flashing can travel along a rafter, across a ceiling joist, or pool on top of a flat section before eventually dripping through. By the time you see a damp patch on your ceiling, the water may have been getting in for some time.
The most direct warning signs to look for from ground level or from inside the loft are:
Understanding why lead work fails helps you ask better questions when getting a repair quoted, and helps you spot whether a proposed repair is actually addressing the root cause.
Lead sheet is sold in different thicknesses, identified by code numbers. Code 3 (1.32mm thick) is generally the minimum for soakers. Code 4 (1.80mm) is used for most standard flashings. Code 5 (2.24mm) is used for valley gutters, parapet gutters and flat roof coverings where additional durability is needed. Using code 3 where code 4 is appropriate means the lead will thin and pit more quickly, and is more likely to crack under thermal stress. A common problem is previous repair work carried out using the cheapest sheet available regardless of the application.
Some older lead work, and some poor modern work, relies entirely on mortar to hold the lead in place. Mortar alone is not adequate. Correctly fitted lead should be clipped using lead clips or lead tacks screwed or nailed to the roof structure, with the mortar pointing serving only as a weatherproof seal at the top edge. Without clips, the lead sheet creeps downward over time as it expands in summer heat, eventually pulling the top edge out of the chase and opening a gap.
Lead expands and contracts significantly with temperature. On a south-facing roof slope the lead surface temperature on a warm day can reach 80 degrees Celsius or more. The material needs room to move. When a single piece of lead is run too long without an expansion joint, it has nowhere to go. Over repeated heating and cooling cycles it work-hardens, then cracks. This is a particularly common failure on valley gutters and parapet gutters where a single sheet has been run the full length for convenience.
A chimney stack requires several separate pieces of lead to waterproof it correctly - a front apron, two sets of step flashings up each side, soakers beneath the stepped courses, and a back gutter or back flashing behind the stack. The back gutter takes the most water because it catches anything running down from above. A common problem is the back gutter being too shallow, so in heavy rain the water overflows the lead edge and runs down the back of the stack.
On older properties the pointing around the lead chase can also be lime mortar that has become porous over decades, allowing water to track along the mortar course even when the lead itself looks intact. Repointing alone is sometimes sufficient to stop a slow leak, but an inspection from the roof is needed to identify which element has failed.
Lead sealant compounds and waterproof tape are sometimes applied as a temporary fix over cracked or lifted lead. These materials can delay water ingress for a season or two, but they are not a permanent solution. Sealant loses adhesion as the lead moves, tape lifts at the edges, and in the meantime the underlying problem continues. When an inspector eventually looks at the roof, layers of old sealant can also make it harder to assess what is going on underneath. A repair that strips out and replaces the failed section properly is the only reliable outcome.
The main categories are:
A flashing repair is not simply a case of pressing new lead over the old. We start by lifting the tiles or slates immediately below the flashing to check the condition of the soakers or underfelt. If water has been getting in, the felt may be split, the battens may have softened, or there may be rot in the decking. Any of that needs to be dealt with at the same time - there is no point fitting a perfect flashing onto a compromised substrate.
The old lead is stripped out entirely. The chase in the brickwork is raked clear of old mortar and recut if necessary to accept the new lead cleanly. New lead sheet of the correct code is cut to length - a maximum of 1.5 metres per bay for flat sections, shorter for stepped work - and dressed into the chase and over the tiles below. Clips are fixed at the appropriate centres. The chase is pointed with a fresh mortar mix to seal the top edge. Tiles are refitted and pointed where required.
If the chimney stack brickwork is also pointing or repointing is needed while the scaffolding or staging is in place, it makes sense to do it in the same visit. Getting up to a chimney safely takes time and equipment; combining work saves cost and disruption.
Lead sheet fitted correctly to the right code and specification is one of the longest-lasting roofing materials available. A well-fitted lead valley or chimney flashing will typically perform for several decades before it needs replacing. Soakers and flashings fitted with modern clips and correct expansion provision have a similar lifespan. That said, the mortar pointing at the top of the chase will need inspecting and repointing periodically - usually every 10 to 20 years depending on exposure. Mortar is the weak point, not the lead itself.
The lifespan of a poor installation is a different matter entirely. Lead fixed without clips and laid in overlong bays can fail within a decade. That is why the method matters as much as the material.
Lead work is priced by the job rather than a simple rate per metre, because the access required varies significantly - a chimney mid-slope needs scaffolding or a tower, a low-level porch flashing does not. As a general indication, having a chimney stack fully re-flashed with new step flashings, soakers, apron and back gutter on a typical two-storey house typically falls in the range of £500 to £1,200 depending on the size of the stack, the number of sides to be flashed and the access needed. A straightforward front apron replacement on a smaller stack can be considerably less.
Valley gutter relining in lead sheet is priced per linear metre and typically costs in the range of £80 to £150 per metre, again depending on width, existing structure and access. Flat roof lead coverings are priced per square metre and can range from £100 to £200 per square metre for lead sheet, reflecting the weight and cost of the material and the labour-intensive nature of dressing and joining it correctly.
These are typical current UK ranges. A proper price for your specific roof requires someone to see the existing flashing, assess the substrate and confirm the access required. Call us to arrange a roof survey in Aylsham and we will give you a clear, itemised figure before any work is agreed.
We carry out lead work throughout Norfolk, across Norwich and surrounding areas including Sprowston, Hellesdon, Taverham, Costessey and Thorpe St Andrew. If you have noticed any of the warning signs described above, the sensible move is to get the flashing inspected promptly.
A small area of failed flashing can allow water to enter slowly over months without causing visible damage. By the time a damp patch appears on a ceiling, the water has often been sitting on ceiling plasterwork, insulation or timber for long enough to cause secondary problems. Catching and fixing a flashing early is nearly always cheaper than dealing with the ceiling, plasterwork and potential structural timber repairs that can follow a long-running leak.
If you are getting quotes from roofers for lead flashing work, here are the practical questions worth asking:
A roofer who can answer all of those questions clearly and specifically is one who knows what they are doing. Vague answers or resistance to those questions is a signal to look elsewhere.
To book a lead work inspection on your Aylsham property, call Norwich Roofers directly. We will inspect the flashing, explain exactly what has failed and why, and give you a straight answer on what the repair involves and what it will cost.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
