Lead Work in Bungay

Expert Lead Work
in Bungay

Why Lead Work Fails - and What to Look For

Lead work is the waterproofing detail that sits at every joint, junction and abutment on a roof. It seals chimneys to the main roof slope, bridges the meeting point of two pitches in a valley, and wraps around dormers, skylights and parapet walls. When it works, you never think about it. When it fails, water finds a way in quickly - and by the time you see damage inside, the problem has usually been building for months.

The warning signs are worth knowing, because catching them early saves money. A damp patch on a chimney breast wall, particularly after heavy rain, is one of the most recognisable signs of failed chimney flashing. You might also see white salt staining on an internal wall near the top - that is moisture working through the masonry repeatedly over time.

What the Warning Signs Actually Tell You

Different symptoms point to different failures, and knowing which is which helps you describe the problem clearly when you call a roofer.

• Damp ceiling patches below a valley: The lead lining the valley has split, lifted or been pushed out of position. Valleys carry a large volume of rainwater and are under constant movement stress as the roof timbers expand and contract.
• Stained or bubbling plaster on a chimney breast: Step flashings or the back gutter behind the chimney have failed. The back gutter sits in the angle where the chimney meets the uphill slope - it is the most vulnerable point and the most common source of chimney damp.
• Damp appearing at a flat roof edge or parapet wall: Lead capping or upstand flashings have lifted, split or been pushed back by frost. Water pools behind the lifted section and soaks into the wall.
• Visible cracks in lead with a white crystalline crust: This is lead carbonate forming where the metal has fatigued. It often follows years of thermal movement without adequate expansion joints. Lead expands and contracts significantly with temperature, and fixings or mortar that hold it too rigidly cause splits over time.
• Mortar fillets crumbling away from a chimney: Mortar was used instead of lead at some point - a cost-cutting measure that almost always fails within a decade. Mortar cannot flex and cracks as the chimney stack moves independently of the roof.
• Water appearing after wind-driven rain but not ordinary rain: Step flashings have lifted slightly at the top. In calm rain they shed water, but under wind pressure water forces its way underneath. A proper step flashing is dressed into a raked mortar joint, not just stuck to the surface.

What Causes Lead Work to Fail Prematurely

Good-quality lead work, installed correctly, should last several decades before it needs attention. When it fails much sooner, the cause is almost always one of a handful of specific problems.

Thermal movement without expansion joints. Lead moves considerably as temperatures swing between summer heat and winter frost. A long run of lead fixed without expansion joints will buckle, crack and eventually split. Each section of lead flashing should be kept to around 1.5 metres, with dressed overlaps that allow movement.

Incorrect code of lead. Lead is graded by code numbers - the higher the code, the thicker the sheet. Different applications require different codes. A valley needs heavier lead than a small step flashing. Using undersized lead in a high-wear position means the material fatigues and thins much faster than it should.

Poor fixings. Lead should be clipped or wedged, not nailed through. Nails create fixed points that stop the lead moving naturally, concentrating stress until it splits at the fixing point.

Mortar instead of lead. A mortar fillet around a chimney or abutment may look neat when first applied, but it is not a substitute for formed lead flashing. It cracks, loosens and allows water behind it - often within a few years.

Roof alterations without proper detailing. When an extension is added, a dormer cut in, or a velux fitted, the junction between old and new structure needs new lead work specified correctly for the angle and exposure. Rushed or under-detailed work at these junctions fails quickly.

What Lead Work Actually Covers

Lead is used across several distinct parts of a roof, and problems in one area rarely mean the whole roof needs work. Understanding the different elements helps you have a clearer conversation with your roofer about what needs doing.

• Chimney flashings: These include the apron at the front, step flashings up the sides, and a back gutter where the stack meets the uphill slope. All four sides need to be sealed and dressed correctly.
• Valley linings: Formed lead laid into the angle between two meeting roof slopes. Valleys are high-volume water channels and need lead thick enough to handle the flow without wearing through.
• Abutment flashings: Wherever a roof slope meets a vertical wall - the side of a chimney, a party wall, a dormer cheek - a soaker and cover flashing combination is the correct approach. Soakers slip under each tile course; the cover flashing is dressed into the mortar joints above.
• Flat roof upstands and cappings: At the edges and parapets of flat roofs, lead is dressed up the wall and over the top to stop water tracking back. Where it cracks or lifts, the wall behind becomes saturated.
• Pipe and vent flashings: Soil pipes and ventilation pipes penetrate the roof covering and need a weathertight collar. A lead slate is the most reliable long-term solution here.

What Good Lead Work Looks Like

When a roofer completes lead work properly, the lead should be neatly dressed into joints - not just sitting on top of the surface and sealed with mastic. Mastic-only joints fail within a few years as the sealant dries out and pulls away. The correct method uses lead wedged or tucked into raked mortar joints, then pointed over with fresh mortar.

Lead surfaces should have an even, slightly rippled finish from dressing rather than being stretched flat. Flat, shiny lead that has been hammered tightly is under tension and will crack sooner. A good roofer works the lead with a bossing mallet and stick to shape it around corners and details without thinning the material.

Expansion joints should be visible at regular intervals on any long run of flashing. If you see a single unbroken length of lead running two metres or more without any overlap, that is worth questioning.

Repair or Replace?

Small areas of failed lead - a split step flashing, a lifted apron - can often be repaired without replacing the whole detail. The decision depends on the age and overall condition of the existing lead. If the surrounding sections are thinning, corroding or already poorly fitted, a full replacement of that detail is the better investment. Patching deteriorated lead gives only short-term relief.

If damp has been entering for some time, the timber beneath may also need checking. Wet timbers under lead flashings can develop rot, particularly at the foot of chimney stacks and in valley boards. A roofer who does not check the substrate before relaying is leaving a potential problem in place.

Talk to Diss Roofers About Lead Work in Bungay

We carry out lead work across Bungay and the surrounding area. If you have spotted any of the warning signs described above, it is worth getting a roof inspection before any work is agreed.