The Property

Warm Construction Lead Flat Roof – York, North Yorkshire

This project was carried out to a Grade II listed property close to York city centre. The building had been somewhat neglected in recent decades and the lead roof required replacement as part of a wider schedule of refurbishment being undertaken by GNR Roofing Services.

Originally, the house formed part of a larger mansion set back from one of the major routes into York. Although the property has been altered and sectioned over the years, it still retains many original architectural features that require sensitive restoration and careful detailing.

The lead flat roof was one of the key elements of the refurbishment. Because the property is listed and the roof area is prominent within the historic fabric, the works required a considered approach to lead bay sizing, thermal movement, insulation, support and long-term weathering performance.

Why the Existing Lead Roof Needed Replacing

The existing lead roof had reached the point where renewal was required rather than local repair. On older lead flat roofs, failure often develops through fatigue, split joints, poor bay sizing, restricted movement, ponding water or deterioration of the substrate below.

In this case, the original bay configuration was a particular technical issue. Lead sheet must be divided into correctly sized bays so that it can expand and contract naturally. Oversized bays, poor fixing and insufficient movement provision can place stress on the lead and significantly reduce its service life.

The replacement roof was therefore designed as a warm construction lead flat roof, allowing the building to benefit from improved thermal performance while retaining a traditional lead finish suitable for the property.

Leadwork Standards and Technical Approach

This project was completed using a standards-led approach focused on lead sheet performance, warm roof build-up, correct bay sizing and durable detailing.

• BS 6915 informed the design and installation of the fully supported lead sheet roof covering.
• BS EN 12588 governed the rolled lead sheet material specification.
• LSTA guidance informed lead bay sizing, roll placement, fixing, movement allowance, clip design and general good practice.
• Warm roof principles informed the insulated roof build-up, vapour control layer and support arrangement beneath the lead covering.

Code 5 lead was used and the original layout was altered to reduce the bay sizes to suitable lengths. A central ridge detail was formed to divide the roof into more appropriate sections, helping the leadwork perform correctly over time.

Specification of Works

Preparation and Removal

• Carefully stripped the existing lead flat roof covering where renewal was required.
• Reviewed the original lead bay layout, laps, rolls, falls and perimeter details before replacement.
• Assessed the existing substrate and roof structure prior to forming the new warm roof build-up.
• Coordinated the leadwork with the wider refurbishment and roofing works being undertaken by GNR Roofing Services.
• Protected the listed building fabric and surrounding roof areas throughout the works.

Warm Roof Build-Up and Support

• Prepared the roof deck to receive the new insulated warm construction build-up.
• Installed exterior-grade plywood to provide a suitable support layer for the lead roof system.
• Included PIR insulation products as part of the warm roof construction.
• Installed a bitumen-based self-adhesive vapour control layer to help manage moisture movement within the roof build-up.
• Prepared the roof falls, ridge arrangement and lead bay layout to suit the revised specification.

Leadwork Installation

• Installed new Code 5 lead to the main flat roof area.
• Formed a central ridge detail to reduce bay lengths and improve compliance with good leadwork practice.
• Set out the lead bays to suit movement, exposure, drainage and the geometry of the existing roof.
• Formed perimeter apron details before the surrounding slates were installed.
• Designed and formed customised stainless steel clips to secure the leadwork correctly.
• Installed associated lead hips, ridge details, chimney flashings, aprons and stepped flashings as part of the wider package of works.
• Completed further leadwork to the entrance canopy, side roof area and rear pediment details.

Finishing and Protection

• Checked lead bays, rolls, clips, flashings and perimeter junctions for continuity and movement allowance.
• Applied appropriate finishing treatment to new leadwork where required.
• Coordinated final detailing with the surrounding roof coverings and refurbishment works.
• Protected the completed leadwork from unnecessary foot traffic and following trades.

The Materials

This project used a combination of traditional leadwork materials and warm roof components, each selected to support durability, movement control and long-term weathering performance.

• Code 5 lead
• Exterior-grade plywood
• PIR insulation products
• Bitumen-based self-adhesive vapour control layer
• Stainless steel clips
• Copper fixings
• Lead-compatible finishing products

If you are comparing lead materials for a similar warm roof or flat roof detail, our shoppable lead chart is a useful starting point. For broader product learning, see The Lead Handbook and our lead roofing guides.