Why Period Properties in Winchester Require Special Lead Flashing Care
.png&w=3840&q=75)
Winchester features some of the finest historic architecture in Southern England. From timber-framed Tudor structures to elegant Georgian brick terraces, maintaining these buildings requires deep architectural understanding. When it comes to junctions, valleys, and chimneys, modern silicones and mastics have no place. Traditional sheet leadwork is the only material that preserves both the structure and character of a period home.
The Chemistry of Lead in Heritage Roofing
Milled sheet lead, manufactured to BS EN 12588 standards, is extremely dense and flexible. When exposed to clean air, fresh lead reacts with oxygen to form a thin grey protective coat of lead carbonate. This oxide skin is highly stable, shielding the underlying lead metal from corrosion. To ensure it cures correctly, a specialist roofer must apply patination oil immediately after installation to prevent white carbonate run-off staining the ancient clay bricks.
Crucial Leadwork Guidelines for Period Homes:
- Code Selection. We use Code 4 sheet lead for simple flashings, but period valleys and box gutters require heavier Code 6 or 7 lead to resist buckling under snow loads.
- Thermal Expansion. Lead moves. A piece of lead flashing must never be longer than 1.5 meters, nor should it be fixed on all four sides. It must be laid in overlapping sections, secured with lead wedges, and allowed to slide freely inside the rafter structure.
- Lead Welding over Mastic. In period valleys, joints must be hot-welded using an oxy-acetylene torch rather than bonded with silicones. Weld lines provide solid, molecular bonds that last centuries, whereas mastics crack and dry out under sun exposure.
Preserving Local Winchester Clay Bricks
Historic lime mortar is much softer than modern Portland cement. If you point lead flashings into period brickwork using hard cement, thermal movement of the lead will crack the ancient brick faces. We use traditional hydraulic lime-mortar mixes matching the historic building fabric to ensure the bricks breathe and movements are absorbed without structural damage.
The Hazard of Modern Polyurethane Coatings
Applying modern paint coatings or liquid rubber sealants over historic leadwork to fix quick leaks is a severe mistake. These coatings prevent the metal from breathing, trap moisture against underlying rafters, and degrade the historic character of listed buildings, leading to enforcement notices from local planning authorities.
Get a Free Quote
No guesswork, no cutting corners. Tell us about your project.