North Walsham Roofers provides lead flashing and weathering services for properties in Swanton Abbott, dressing and fixing lead to the correct Code specification on chimneys, dormers, skylights, and valley junctions.
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Lead is used wherever your roof covering meets a vertical or near-vertical surface and a watertight seal is needed. The most common locations are chimney stacks (stepped flashings, back gutters, and aprons), dormer cheeks and heads, the upstands around roof windows and skylights, and the valleys where two roof slopes meet. At each of these points, lead is cut, dressed into shape, and fixed in a way that allows it to move slightly with temperature changes without opening up a gap.
When this lead is in good condition, these junctions are the most weatherproof parts of the roof. When it fails - through age, poor original installation, or physical damage - these same points become the most likely source of a leak. Water does not have to pour in; even a small gap at a chimney flashing can allow enough moisture to cause serious damage to a chimney breast or ceiling over time.
This is the question most homeowners face once a problem with lead work is diagnosed. The answer depends on the condition of the existing lead, how it was originally installed, and where the failure has occurred. Neither repairing nor replacing is always the right answer - the correct choice depends on an inspection of the actual material.
As a general rule, repair is appropriate when the lead itself is in sound condition but a localised failure has occurred - for example, a mortar chase that has cracked and allowed the flashing to pull away slightly, or a single bay where the lead has slipped. In these cases, lifting the affected section, re-dressing it where needed, re-wedging it into a freshly cut chase, and re-pointing can produce a result that will last as long as new lead.
Replacement is the better choice when the lead is old and has begun to crack from thermal fatigue, when the Code used was too light for the application and the lead has rippled or split, when a previous contractor has bodged the original with too many overlapping pieces or excessive sealant, or when the lead has been stolen. Attempting to repair lead that is fundamentally too thin, cracked through, or incorrectly dressed is a short-term fix that will fail again.
You will not always be able to tell from a visual inspection whether repair or replacement is appropriate, but there are signs worth noting. If you can see that the lead has visibly rippled or buckled across its surface, that is a sign of thermal movement in lead that was laid in bays that are too long. This stresses the material and eventually causes cracks. Lead that has been in place for many decades and shows fine surface crazing may still be perfectly serviceable; lead with actual splits through the thickness is not.
If you can see that flashing tape or mastic sealant has been used over the lead at some point, that is a sign of a previous repair that has or will fail. Mastic and self-adhesive tape are not long-term solutions for lead joints. They typically last three to five years before UV degradation and thermal movement cause them to lift or crack, and they can mask the underlying condition of the lead beneath.
Internally, a tide mark or stain on a ceiling directly below a chimney or dormer is a sign that water has been getting in. The stain does not always appear directly below the entry point - water can travel along roof timbers before it drops - so an internal inspection of the roof space is a useful part of any assessment.
A properly executed repair costs less than a full replacement and, done correctly, can give many more years of service. The key word is properly. Lifting a section of lead, re-cutting the chase, dressing the lead back flat, re-wedging with lead clips, and re-pointing with an appropriate mortar is skilled work. If the repair is carried out on lead that is still in good overall condition, it is the most cost-effective approach.
A repair also makes sense when only one element of a junction has failed while the rest is sound. For example, the apron (the front flashing at the base of a chimney) may have slipped while the stepped side flashings are still well fixed. Replacing the whole chimney lead when only the apron needs attention is unnecessary expenditure.
Old lead that has been repaired multiple times, or lead that was originally installed with inadequate material or incorrect technique, is often cheaper in the long run to replace fully rather than repair again. Each repair adds cost, and if the underlying lead is failing, those repairs will not hold.
Replacement also makes sense when there are structural issues behind the lead - for example, a chimney stack where the brickwork joints have eroded to the point where there is nothing sound to chase the new lead into. In that case, the brickwork needs repointing before new lead work can be properly fixed. A contractor who replaces the lead without addressing the masonry beneath is setting up the next failure.
For a full chimney lead replacement on a standard two-stack property, costs typically range from £400 to £800 depending on chimney size, access requirements, and the extent of any masonry work needed alongside. Valley replacements will vary more widely depending on length and pitch. These are guide figures; a site inspection is the only way to price accurately.
If your property needs a repair to a single section of flashing or a full lead replacement on a chimney or valley, call us to arrange an inspection and we will give you a clear assessment of which approach makes sense for your roof.
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Call any time. Calls are answered day and night and passed straight to our roofers.
