Failing lead flashing is one of the most common reasons Hethersett homeowners find water inside their roof - here is how to spot the warning signs before the damage spreads.
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Lead is the material of choice wherever a roof meets a vertical surface - around chimney stacks, along parapet walls, in valleys between two roof slopes, and where a flat roof or extension abuts the main house wall. It is pressed, dressed and fixed by hand so that it sits tightly against the masonry or tiles without gaps. When it is done properly, it outlasts almost every other roofing material on the house. When it is done badly, or when old lead finally fails, water tracks straight into the roof structure.
We carry out all types of lead work: step flashings, soakers, back gutters, valley linings, and flat roof coverings. Every piece is cut from code-appropriate lead sheet - the thickness varies depending on where it sits and how much movement it needs to handle. Thinner sheet on a small soaker, heavier code on a flat roof or a wide chimney back gutter. Getting that right is basic to doing the job correctly.
Most lead failures give you clear warnings before serious water damage sets in. The difficulty is that some of these signs appear inside the house, some on the roof itself, and some only become visible after a run of wet weather. Knowing what you are looking at means you can act early rather than waiting until plasterboard is soaked or timbers are rotting.
You do not need to go on the roof yourself to spot several warning signs. Standing back and looking at the chimney stack, the roof valleys and the junction between a lean-to roof and the house wall will often tell you enough to know whether a closer look is needed.
Some lead failures are intermittent and only show up in certain conditions. A flashing that is slightly lifted may only allow water in when the wind is driving rain in a particular direction. A split valley liner may only overflow when the rainfall is heavy enough to overwhelm a partial blockage. If you notice damp patches that appear and then seem to dry out, that pattern is worth noting when you call us - it helps narrow down the likely cause.
Understanding why lead fails helps you have a more informed conversation with any roofer and gives you a basis for judging the quality of the repair being proposed.
Lead expands and contracts significantly with temperature. A long, unbroken run of lead flashing that has not been properly divided into shorter sections with expansion joints will eventually crack or buckle. The correct way to install step and cover flashings is in sections no longer than around 1.5 metres, with small laps between each piece to allow for movement. Flashings installed as one long piece - often a sign of a rushed or inexperienced job - are likely to fail within a few years.
Lead sheet is sold in codes that refer to its thickness and weight. Code 3 and Code 4 are the lightest and are only suitable for soakers and small flashings in sheltered positions. Code 5 and above is needed for chimney flashings, back gutters and valley linings where there is more exposure and more water movement. Using underweight lead to save money is one of the most common causes of early failure on chimney and valley work.
Where lead is fixed into a mortar joint, the pointing must be done correctly. Weak or crumbling mortar lets the lead pull free. Pointing that is too hard and inflexible cracks as the lead moves. A properly pointed flashing uses a mortar mix suited to the brick or stone it is being fixed into, and the top edge of the lead is turned into the raked joint before pointing - not just stuck on the surface with sealant.
A common problem across older roofs is the layering of temporary repairs over previous temporary repairs. Bitumen paste, lead repair tape, silicone sealant and flashing tape are all sold as repair products, but none of them last more than a few seasons and all of them mask the real condition of the lead underneath. By the time a proper roofer looks at the flashing, there can be several layers of different products, each hiding further deterioration. Stripping back to the lead and assessing its actual condition is the only reliable way to know what you are dealing with.
Well-installed lead in a sheltered position can last 60 to 80 years or more. Lead on a chimney stack or in a valley, subject to more movement, more water and more UV, typically has a working life of 40 to 60 years. If your home was built or substantially re-roofed in the 1960s or 1970s and the original lead has never been touched, it is approaching or past its natural lifespan and worth having inspected.
When we come to carry out lead work on a Hethersett property, the process follows the same steps regardless of whether it is a small flashing repair or a full chimney lead replacement.
We start by stripping back any existing lead and any sealant repairs so we can see the substrate clearly. We check the underlying structure - the boarding, felt or masonry - for any water damage that needs addressing before new lead goes on. There is no point putting new lead over rotten timber or crumbling mortar.
New lead is cut and dressed on site. Chimney flashings are raked into the mortar joints and pointed. Soakers are slipped in under the tile courses. Valley liners are cut to fit the angle of the valley and fixed with clips. Where a flat roof section uses lead, it is dressed over the edge and secured with appropriate fixings. Every joint and upstand is formed by hand using the correct tools so the lead sits flat and tight.
After the new lead is in place, we check the adjacent tiles or slates and re-bed or re-point any that have been disturbed during the work. We clear any debris from gutters in the immediate area before we leave.
Lead work pricing varies quite a bit depending on the scope of the job. A straightforward re-pointing of an existing chimney flashing where the lead itself is still sound might cost £150 to £300. Replacing all the lead on a standard chimney stack - step flashings, cover flashings and back gutter - typically runs from £400 to £800 depending on the size of the stack and the access involved. Valley work depends on the length of the valley and the tiles either side; a full valley relining on a typical semi-detached house is usually in the range of £500 to £1,200.
The cost of lead sheet itself has risen with metal prices generally, so any quote you received more than two or three years ago is likely to be out of date. Ask any roofer quoting the job to specify the code of lead they are using and the total length or area being replaced - that gives you a basis for comparing quotes properly.
A chimney stack is the most complex lead detail on most houses. It requires flashing on all four sides: step flashings down the two sloping sides, a front apron at the low edge, and a back gutter at the high edge where water from the main slope collects before draining off to either side. Every one of these elements needs to be correctly sized, correctly coded and correctly fixed. A failure in any one of them can send water into the roof.
The back gutter is the piece most often done poorly or neglected entirely on older roofs. It sits out of sight on the high side of the stack and collects a significant amount of water in heavy rain. If it is undersized, cracked or blocked with debris, water backs up behind the stack and soaks through. Chimney back gutter failures are a particularly common cause of the damp patches on chimney breast walls that homeowners sometimes mistake for rising damp or a condensation problem.
Lead is also used to cover small flat roof areas - bay windows, porch roofs, dormers - where a traditional look is wanted or where the area is too small and complex for a felt or EPDM system to sit neatly. A lead flat roof needs to be laid in bays, with drips and rolls formed between sections to manage thermal movement. Lead laid as a single unbroken sheet over a flat area will crack and fail regardless of its code, because it has nowhere to go when it expands. If you have a lead flat roof that is cracking, the first thing to establish is whether it was laid in the correct bay widths in the first place.
Soakers are the small, often overlooked pieces of lead that sit under each course of tiles where a sloping roof meets a wall or a dormer cheek. Each soaker hooks over the tile batten and tucks under the tile above, directing water away from the junction. They are invisible once the tiles are laid, which means they are also invisible when they fail. Signs of soaker failure are usually a damp patch running down a wall at the base of a roof slope, or staining on a ceiling directly below a tiled junction.
Valley liners carry water from the junction of two roof slopes down to the gutter. In an open valley the lead liner is visible; in a swept or laced valley it sits under the tiles. Blockages from moss, leaves or debris are a common problem in valley gutters and can cause water to back up even when the lead itself is sound. Clearing the valley and checking the liner condition at the same time makes sense.
This is the question most homeowners want answered before work starts. The honest answer depends on the age and condition of the existing lead. Lead that is sound, correctly coded and still sitting flat in its mortar joints may only need re-pointing and a clean. Lead that is cracked, that has been repeatedly repaired with sealant, or that is showing signs of fatigue - small cracks running across the surface, sections that have become brittle - needs replacing. Patching lead that is at the end of its life buys a short amount of time at a similar cost to doing the job properly.
If you are uncertain, ask the roofer to show you the lead before they remove it and to explain specifically what they found. A roofer who can point to the crack, show you the underweight code or demonstrate where the mortar has failed is giving you information you can rely on. One who simply says it needs replacing without showing you why is not.
If your property is within reach of Norwich, call us to discuss the job.
We will inspect the lead work on your Hethersett property and explain clearly what we have found, what the options are, and what we recommend. No pressure, no upselling, no jargon. Call us to arrange a roof survey and get a proper assessment of the lead work on your home.
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