Fakenham Roofers carries out lead flashing, valley lining, soakers, and dormer lead work for homeowners in Dersingham, working to BS EN 12588 standards.
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Most lead failures announce themselves inside the property before the damage on the roof is visible from the ground. By the time you see a stain on a ceiling or a damp patch on a chimney breast wall, water has usually been finding its way through for some time. Knowing the warning signs - and understanding what causes them - lets you act before the damage spreads into plasterboard, ceiling timbers or wall cavities.
This page explains the most common signs that lead work is failing, what lies behind each one, and what a proper repair involves. We carry out lead flashing, valley lining, soakers, dormer flashings, and lead-lined gutter work across Norfolk from our base in Fakenham, and we work to BS EN 12588 - the British Standard for milled lead sheet - on every job.
A brownish stain or soft patch on a ceiling directly below a chimney stack is one of the clearest signs that the flashing at the base of the stack has failed. The flashing - or more precisely the combination of step flashings up the sides and the apron at the front - is the watertight junction between the lead sheet and the chimney brickwork. When this joint opens up, rain runs straight down the outside of the chimney and into the roof space.
The cause is usually one of three things. The mortar joint holding the top edge of the flashing in place has decayed and opened up, allowing water to run behind the lead rather than over it. The lead itself has pulled away because it was fixed in a single length that is too long and has worked itself out of the chase through thermal movement. Or a previous repair used a bitumen-based strip product rather than properly formed lead, and that strip has now lifted or cracked.
On older brick chimney stacks - common across Norfolk properties - frost repeatedly attacking open mortar joints is the dominant cause. The joint looks intact from a distance but is hollow behind. The fix is to rake the old mortar back, dress in new lead correctly fixed with clips, and re-point the chase in a suitable mortar.
Dormers are another common source of lead failure. A dormer has multiple lead details: an apron at the base where the dormer cheek meets the main roof slope, step flashings up each side, and often a gutter along the base that may be lead-lined. Any one of these can fail independently.
A damp patch on the wall inside the dormer, particularly in a corner or along the base of the cheek, usually points to the side flashing or the apron. On timber-framed dormers the cheek is often clad in tiles or slates, and the lead soakers hidden under each course can corrode or lift over time. On render-clad dormers, the junction between render and lead is a common failure point - render cracks and water runs behind the flashing edge rather than over it.
Dormers that were added to a property at a different time to the main roof are worth inspecting carefully. The junction between an original roof structure and a later dormer addition can have multiple layers of previous repair, each one added over the last rather than the underlying problem being properly resolved.
A lead valley - the channel formed where two roof slopes meet - relies on continuous, clean lead sheet that drains freely to the gutter. A valley that is leaking or causing water ingress typically shows one of these problems.
The lead has cracked or split. This happens when the original lead was undersized (Code 3 where Code 4 should have been used), when the underlying boarding has deteriorated and is no longer giving the lead adequate support, or when the valley has been walked on and the lead distorted. A crack in a valley is not always visible from the ground - the first sign is often a damp patch on the ceiling of the top floor at the junction of two roof slopes.
The valley has lifted at the edges. If the lead has not been properly clipped and dressed against the tile courses on either side, rain can blow under the edge rather than running down the channel. A valley where you can see daylight under the edge of the lead from roof level needs re-dressing at minimum, and full replacement if the lead is too old and stiff to work.
Debris has dammed the valley. Leaves, moss, and silt that build up in a valley cause water to pond behind the obstruction. Standing water puts the lead under pressure it was not designed for and accelerates deterioration at the edges. The solution to this is maintenance - clearing the valley regularly - not lead replacement, unless the ponding has already caused damage.
White staining on tiles or brickwork below a lead flashing is lead carbonate - a natural byproduct of lead weathering. A small amount is normal. Heavy staining suggests the lead surface has been disturbed, the patina has not been allowed to develop, or the lead is very new. It is cosmetic rather than structural but worth noting.
Dark streaking below a flashing, particularly where moss or algae growth follows the streak, is a sign that water is running off the lead in an uncontrolled way - either because the flashing edge is lifting and water is running under and then out at the bottom, or because the lead is dressed at the wrong angle and pooling rather than shedding. Either warrants investigation.
You do not always need internal damp to know your lead work is under threat. From the ground with binoculars, look at the mortar joints at the base of the chimney stack, the pointing around the chimney pot, and the condition of the coping or cap stones if fitted. Open joints, crumbling mortar, or a leaning chimney pot all let water into the stack from above, and that water has to go somewhere.
A chimney stack with open pointing and failing flashings is essentially an open funnel into the top of your property. Repairing the flashings alone without addressing the stack above them is a partial fix - the water will still find a way in, just by a different route. A proper inspection looks at the full stack: pointing, lead work, pot, and cap or coping.
A lead repair is not simply cutting a new piece of lead and sticking it over what is already there. The old material is stripped back, the substrate and mortar work are inspected, and any underlying issues are dealt with before new lead is dressed in. If the boards beneath a valley are rotten, they are replaced before the lead goes back. If the brickwork at a chimney is friable, it is cut back to sound material before the chase is re-formed.
New lead is cut to the correct BS EN 12588 code for each application and dressed to shape using traditional lead-working tools. Each section is clipped at the fixed end so it can move freely as temperatures change. The top edge is tucked into a raked mortar chase and pointed back in. There are no sealant tubes over the top of a well-executed lead job.
For dormer flashings, the approach depends on the construction. A render-clad dormer may need the render to be cut back before the lead can be properly terminated. A tile-clad dormer cheek requires each soaker to be formed individually and lapped correctly under each tile course - this is time-consuming but it is the right way to do it.
Chimney flashing replacement - stripping old lead, re-pointing the chase, forming and fitting new step and cover flashings and a new apron - typically costs between £350 and £700 for a standard stack in Norfolk. Valley relining costs depend on the length and pitch but commonly falls in the range of £400 to £900 for a typical residential roof. These figures assume reasonable access and a stack or valley in otherwise sound condition; the actual cost depends on what is found when the old material comes off.
We work from Fakenham across Norfolk. As well as Dersingham, we carry out lead work in towns and villages across the surrounding area. If you are in the area and have spotted any of the warning signs above, call Fakenham Roofers and we will arrange a proper look at the roof.
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Call any time. Calls are answered day and night and passed straight to our roofers.
