Defective Lead-Work - Lead Flashing Valley Gulley & Gutter Repairs
Does your property have defective lead work?
Cracking can develop where roof slopes abut dormers, parapet walls and subsidiary roofs, or around objects such as chimney stacks and internal soil pipes that are projecting through the roof. The resulting leaks and damp patches can be seen in lofts, ceilings, walls and chimney stacks.
Lead Flashings are very durable but over a period of time can sometimes come loose. More rarely, old lead valleys, zinc flashings or gulleys may have perished, split or corroded. Mortar fillets are a cheap alternative to lead and are particularly prone to cracking. Short-life tape repairs may even have been applied, or flashings painted to temporarily seal leaks.
These sorts of defects are a common cause of leaks in all types of properties and extensions. Over time, water penetration may have caused adjoining timbers to rot, and an urgent repair is normally required to prevent further deterioration.
Such issues are not too difficult to fix, although replacing any rotting and decayed timbers will add to the complexity and cost.
Damaged lead or zinc flashings should be replaced with new leadwork. Lead is the best material to use. Although relatively expensive, the cost can be mitigated by recycling the valuable old lead. Where a flashing has simply come loose from a wall or chimney breast, it may only need localised re-fixing.
Roofs on terraced houses can also suffer leaks where they meet at party walls. This tends to be worse where each house has a different type of roof covering. In this case, localised stripping will be required with the provision of sheets of lead soakers under the joints, or new flashings to parapets.
Valleys are the junctions between two adjoining roof slopes which allow rainwater to run off in to the guttering. Valleys made with preformed tiles are relatively robust and any defective tiles can be replaced. Traditional open valleys have exposed linings which can, however, deteriorate over time. Furthermore, on roofs clad with large interlocking tiles, it’s also common for the mortar up-stands either side to crack and come loose. They may simply need re-pointing. Alternatively, valleys can be relined using preformed valley trays of glass-reinforced polyester. With older roofs, replacing traditional lead work with matching new materials is advisable.
- To replace a defective lead or zinc valley on a typical slate or tiled roof:
- The old lining is stripped back.
- The timber base is checked to see if it is in sound condition.
- The old lining can then be replaced with new strips of code 4-thickness lead turned back and raised up at the edges.
- A thin layer of fibrous material is inserted between the lead and the valley board (such as breathable membrane roofing felt).
- The lead is finally fixed in place with copper nails hidden under the overlaps.