If you have a leak around a chimney, skylight, or roof valley in Newmarket, there is a good chance the lead work is the cause.
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Lead is the material used to seal the joints where your roof meets a vertical surface, a change in angle, or another roof plane. Chimneys, dormer walls, skylights, bay roofs, roof valleys and flat roof edges all rely on lead to stay watertight. When it is properly installed, lead can outlast the tiles around it. When it fails, water finds a way in quickly and the damage spreads fast into ceilings, timbers and insulation.
Lead work covers several distinct tasks. Flashing is the strip of lead dressed into mortar joints and over the top of tiles or slates to seal a junction. Valley work uses either a continuous lead lining or individual soakers to carry rainwater down the angle between two roof slopes. Flat roof lead work covers areas of flat or near-flat surface, typically on bay window roofs, small outbuildings and porches.
All of these need to be dressed by hand to the correct Code of lead. Code refers to the thickness of the sheet, measured in kilograms per square metre. Code 3 is the lightest and is used for soakers and small flashings. Code 4 is the most common for chimney flashings and step flashings. Code 5 and above are used for valleys, large flat areas and exposed positions. Using the wrong Code is one of the most common mistakes made by roofers who treat lead as an afterthought rather than a skilled trade.
Lead work fails for several reasons. The most common is poor installation from the outset, where the lead has not been properly bedded into the mortar joint, not dressed tightly enough to the surface, or cut too short to overlap correctly. These faults can go unnoticed for years until a heavy rain event pushes water past a gap that should never have been there.
Thermal movement is another cause. Lead expands and contracts with temperature changes, and if a sheet is fixed over too long a run without a proper drip or roll joint, it will eventually crack or pull away from its fixing. The standard maximum length for a single piece of lead flashing is 1.5 metres. Longer than that and you need a lap joint to accommodate movement. A tell-tale sign of this failure is a crack running across the width of a flashing rather than along a joint.
Old lead work simply wears out. Lead that has been on a roof for fifty or sixty years may have thinned through oxidisation and physical weathering to the point where it can no longer be relied upon. At that stage, patching becomes a short-term measure at best.
Mortar joints also fail. The lead itself may be sound, but if the pointing holding it into the masonry has cracked and fallen away, water runs behind the flashing rather than being deflected by it. This is a straightforward repair but one that is easily missed by someone who only looks at the lead rather than the whole junction.
Finally, lead is stolen. It is a valuable metal and flat roofs, porches and valleys are targeted on properties across Newmarket and the wider area. When lead is stripped off, the roof below is immediately exposed to weather and the damage that follows can be severe.
This is the question homeowners in Newmarket ask most often when a lead work problem is identified, and the honest answer is that it depends entirely on the condition of what is already there. There is no single rule, and anyone who says "always replace" or "always repair" without inspecting the work first is not giving you useful advice.
A repair is the right call when the lead itself is in sound condition but a specific, identifiable fault has caused the problem. A cracked mortar joint behind a chimney flashing, a short section of flashing that has lifted at one end, a patch of oxidisation that has broken through on a small flat roof, or a valley soaker that has slipped out of position: all of these are legitimate repair jobs. The lead around the fault is still serviceable, and replacing it would mean spending money on material that has years of life left in it.
Repairs are also appropriate on newer lead work that has been poorly installed. If a previous roofer used the wrong Code, cut the lead too short, or failed to lap joints correctly, the fix may be to re-dress the existing material properly rather than strip it all back and start again. On relatively new lead, that is often the most cost-effective route.
Replacement becomes the right answer when the lead is genuinely worn out, when it has been patched repeatedly and the repairs are no longer holding, or when the coverage is so poor that a proper repair would cost nearly as much as starting fresh. On chimney stacks that have never had correct flashing, or on properties where lead has been stolen and the underlying structure has suffered, full replacement is almost always the better investment.
The age of the property gives you a rough guide. On older properties, if the lead is original or has not been replaced within living memory, replacement is usually the more sensible conversation to be having.
Cost also plays into it. A repair on a single chimney flashing might cost in the region of £150-£300 depending on what is needed. A full chimney re-flash using Code 4 lead, correctly bedded and pointed, typically runs from £400-£800 or more depending on the size of the stack and how many sides need attention. Valley replacement, where the entire lead lining is stripped and relaid, can range from £600-£1,500 depending on the length and pitch of the valley and the Code of lead used. These are indicative figures for the UK currently and will vary with access, scaffold requirements and the condition of the underlying structure.
Before you commit to either a repair or a full replacement, there are several things worth asking any roofer who comes to look at the job.
A roofer who cannot give you clear answers to these questions is not someone you want working on lead. Lead work is not a job that can be hidden behind tiles or pointing after the fact. Good work shows, and so does bad work when the rain comes.
On a chimney, correct flashing involves an apron flashing at the front, step flashings up each side dressed into individual mortar joints in the brickwork, and a back gutter behind the stack to collect any water running off the chimney face. Each piece of lead is fixed with lead clips or wedges before the mortar is packed in and pointed. The lead is dressed tight to both the brickwork and the tiles or slates using a dresser, not just pushed into place by hand.
On a valley, the lead is laid in sections with correct overlaps based on the pitch of the roof. On a shallow pitch the overlaps are longer because water moves more slowly and has more opportunity to be driven back by wind. The edges are turned up to form a check that keeps water on the lead rather than allowing it to creep under the tiles at the sides.
On a flat or near-flat lead roof such as a bay window top, the lead is dressed in bays with separate drip edges and roll joints to manage movement. The falls need to direct water toward a gutter rather than toward the wall. Poor falls are a common fault on bay roofs and lead to pooling water that accelerates wear.
Access affects cost and should be discussed honestly. A chimney flashing at low eaves level on a single-storey extension may be accessible from a ladder or a short tower scaffold. A chimney on a two-storey house will almost always need a full scaffold lift to work safely and to give the lead enough room to be dressed properly. Rushed lead work from an awkward position is a false economy.
If scaffold is going up anyway for other work on a property, it makes sense to include lead work in that visit. Combining jobs saves on the scaffold hire and reduces the disruption to the property. If you are getting tiles replaced or a chimney repointed, ask the roofer to inspect all of the lead at the same time.
For flat roof sections such as porch roofs and bay tops, EPDM rubber is an alternative to lead that some homeowners choose, particularly where lead theft is a concern. EPDM is a single-ply membrane laid in large sheets with very few joints, which reduces the number of potential failure points. It is lighter than lead and less attractive to thieves. On the other hand, lead is the traditional and technically correct material for flashings at junctions with masonry, and EPDM is not always appropriate where the detail requires a dressed joint into brickwork.
The right choice depends on the specific detail, the exposure of the roof, and the preferences of the homeowner. It is a conversation worth having with a roofer who understands both materials rather than one who only works with one of them.
If you have noticed a damp patch on a ceiling below a chimney, below a valley, or below a flat roof section, do not wait for the next wet spell to see if it gets worse. Lead work problems do not resolve themselves, and the water damage behind the scenes can progress faster than the visible staining suggests.
The right first step is a proper inspection from roof level, not a look from the ground with binoculars. Ground-level inspections can miss the detail that tells you whether a repair will hold or whether the lead needs to come off and be replaced. We carry out lead work surveys across Newmarket and the surrounding area. Call us to arrange a survey so we can give you an honest assessment of what the lead is doing and what it actually needs.
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