Chimney flashing
The lead detail sealing where the chimney meets the roof. The single most common source of persistent leaks on Bristol terraces.
Bristol lead work
The detail that makes a roof watertight.
Lead is what seals the awkward joints on a roof: where the tiles meet the chimney, where two pitches meet in a valley, where the roof abuts a wall or a parapet. Every leak on an otherwise sound roof usually turns out to be one of these details, done wrong or worn out.
Good lead work uses the correct weight (code) of lead for the specific job, is fixed and dressed with the right technique, and gets a coat of patination oil so it doesn’t stain the wall below with white streaks. We do the lead work on all our own re-roofs, and take on lead-only jobs where a specific detail has failed and needs redoing.
The main lead details on a Bristol roof.
Any of these can leak if the lead work is old, thin or badly fixed.
Valleys
The lead channel where two pitched roofs meet. Old cracked valleys let water track under the tiles for weeks before anyone notices.
Step, apron and parapet flashing
Where the roof meets a wall (yours or a neighbour's), or runs up to a parapet, lead is what seals the joint.
What proper lead work involves.
The details separate a job that lasts fifty years from one that fails in five.
- Correct code (weight) of lead for the specific detail, not the cheapest available.
- Mortar-fixed or lead-clip-fixed depending on what suits the job.
- Dressed properly around curves and corners, not just folded flat.
- Undercut into the brickwork or masonry, so water can't track back.
- Patination oil applied to prevent the white staining that ruins walls below.
- Existing lead reused where sound, replaced where thin or split.
Where lead work fails.
If any of these apply to your roof, the lead is at the end of its life.
- White streaks running down the wall below the flashing (missing patination).
- Lead visibly cracked, split or torn.
- Sections lifted by wind because the fixings were inadequate.
- Thin, off-code lead that has fatigued from thermal movement.
- DIY silicone sealant patches over old lead (never lasts).
- Damp patches inside near any of the details above.
Lead work questions, answered.
What code of lead do you use?
Code 4 for most standard flashing on a typical Bristol terrace. Code 5 for larger valleys or where more movement is expected. Code 6 or higher on parapets and heavy-use details. The right code depends on the job, not on what's cheapest to buy.
Why does old lead stain the wall below with white streaks?
Fresh lead reacts with rainwater to form a soluble carbonate that washes down the wall as white staining. It's prevented by applying patination oil to the lead once it's fitted, which forms a stable surface layer. Most lead work that stains was fitted without patination.
How long does properly-fitted lead last?
Fifty years or more when done right. Some Bristol chimney flashings are still watertight after 80 years. The failure points are almost always corners and edges, not the flat runs.
Can old lead be reused?
Yes, where it's still sound. Lead can be lifted, cleaned, and re-laid over a new detail, which saves both cost and materials. If it's cracked, torn or overly fatigued, it's replaced.
Is DIY lead sealant ever a good idea?
No. Silicone or bituminous sealant over old lead lasts one or two seasons at most, hides the underlying problem, and often causes worse leaks when it eventually fails. A proper lead repair is far cheaper long term.
Do you offer a guarantee?
Yes. Lead work carried out as part of a new roof qualifies for the CORC 10-year Insurance-Backed Guarantee. Stand-alone lead repairs carry a workmanship guarantee set out in the quote.
Recent projects across Bristol.
Leak near a chimney or valley?
It's almost always the lead. Get in touch and we'll take a look.