Leadwork in Knowle
Chimney flashings, back gutters, valleys, bay tops and dormer cheeks. Lead is where most roof leaks really start, and where good workmanship shows most.
The lead details on a typical Knowle roof
Chimney flashings
Stepped flashings down the sides, an apron at the front and a back gutter behind. Each piece is dressed into the mortar joints and has to let the chimney and the roof move separately.
Back gutters
The section behind the chimney catches everything running down the slope above it. If it is too short, split or blocked with debris, the water ends up in the loft.
Valleys
Where two slopes meet, a lead-lined valley carries a lot of water. Lead that is too long in one piece cracks; laid correctly in shorter lengths it lasts.
Bays, porches and dormers
Lead-covered bay tops and dormer cheeks are common on older houses and are often patched rather than relaid. Relaying them properly ends the cycle.
Abutments
Where a roof meets a higher wall, such as a rear extension against the house, a stepped or cover flashing keeps water out of the joint.
Parapets and box gutters
Less common on Knowle houses, but where they exist they need careful lead or membrane work because water has nowhere else to go.
What good leadwork looks like
Right code for the job
Lead sheet comes in different thicknesses, called codes. Flashings, gutters and bay roofs each need a suitable code, laid in lengths that allow for expansion.
Chased, wedged and pointed
Flashings go into a cut joint, are held with lead wedges and pointed. Lead stuck to a wall with sealant alone will come away.
Patinated
We finish new lead with patination oil, which helps prevent white staining from running onto tiles and walls in the first rain.
Not mastic
Mastic and tape are a temporary stop at best. If you see them around your chimney, it is usually a sign the lead needs renewing.
Leadwork FAQs
How do I know the leak is the lead?
Damp around a chimney breast, or in the ceiling near where a roof meets a wall, often points to the flashing. We confirm by inspecting it on the roof.
Can you replace just one flashing?
Yes. We replace what has failed. If the rest of the chimney lead is close behind, we will tell you, and you can decide.
Do you use lead substitutes?
On some jobs a lead-free alternative makes sense, for example where theft is a concern. We explain the choice in the quote.
Is leadwork covered by your guarantee?
Yes. See our guarantee.
Damp round the chimney?
We will find out whether it is the lead and put it right properly.