Why lead is used on traditional slate roofs
Lead is workable, durable and well suited to forming weatherproof details around changes of plane and difficult junctions. On traditional roofs it may be found in valleys, flashings, soakers, gutters, chimney details, dormers and abutments.
Common leak locations
Valleys
Valleys carry concentrated water from two roof slopes. Splits, poor laps, blocked outlets, damaged surrounding slates or inadequate detailing can all cause leakage.
Chimney flashings and soakers
Leaks around chimneys may come from the flashing system, masonry, pointing, pots or caps rather than the main roof covering.
Abutments and parapets
Where a roof meets a wall, the combination of soakers, flashings, secret gutters or other details must be compatible with the slate and wall construction.
Dormers and rooflights
These introduce multiple junctions into the roof and should be inspected as complete systems, not just at the most obvious wet point.
Why patching can fail
Sealants and surface patches can sometimes suppress a symptom temporarily without correcting the underlying detail. Traditional roofs also move with temperature and weather, so rigid or incompatible patching materials may fail quickly or trap moisture.
A durable repair normally follows the intended water path: shedding and lapping water out of the roof, not trying to glue the junction shut from the surface.
What affects the cost of leadwork?
Access, length and width of the detail, lead code/specification, timber or substrate condition, the need to lift surrounding slates, chimney or masonry repairs, temporary protection and complexity all matter. A long valley replacement can be a substantial job even if the slate covering itself is largely retained.
What to ask for in a quotation
- Which exact detail is believed to be failing.
- Whether surrounding slates will be lifted and reinstated.
- What lead specification and bay lengths are proposed.
- Whether substrate or timber repairs are included.
- How abutments, end details and outlets will be formed.
- Whether associated chimney or masonry work is required.
Leadwork during a full re-slate
A major re-slate is the opportunity to renew ageing valleys and flashings properly while the surrounding covering is already being lifted. Excluding them from the scope to reduce the headline price can be false economy if they are already near the end of their useful life.
For whole-roof budgeting, see our slate roof replacement cost guide. For listed properties, see listed-building roof replacement in Scotland.
Further reading
Traditional roof details should be designed and installed to recognised current technical practice. Historic Environment Scotland guidance is particularly useful where historic fabric and compatible materials are involved.