Lead Dormer Windows: Advanced Detailing & Heritage Guide
Dormer windows are one of the most characterful features of traditional buildings. With the right approach, lead dormer windows can combine durability with architectural elegance. This guide covers advanced detailing for cheeks, aprons, bay divisions and decorative rolls, aligned with Leadwork Standards.
1. Code Selection
Code 5 lead remains the standard for dormer roofs and cheeks. Code 6 is advised for larger dormers or where wind exposure is high.
2. Cheeks & Aprons
Cheeks should be divided vertically with welted joints to shed water away from glazing. Aprons must extend 150 mm up the dormer face and lap 150 mm over the main roof covering.
3. Bay Sizing & Joints
Dormer roofs should be divided into bays no longer than 1.5 m (Code 5) or 2.0 m (Code 6). Wood-cored rolls are recommended for heritage appearance while managing thermal expansion.
4. Decorative Finishes
Heritage dormers often feature scalloped edges, decorative rolls, or lead bosses at corners. These details should be carefully designed so they remain waterproof and practical.
5. Integration with Main Roof
Dormer coverings must integrate seamlessly with soakers, side flashings and the main roof finish. Incorrect overlaps are a frequent cause of leaks.
FAQs
What lead code is best for dormer windows?
Code 5 for most cases, with Code 6 for larger or more exposed dormers.
Do dormer cheeks need joints?
Yes. Vertical welted joints prevent distortion and shed water away from windows.
Can dormers have decorative lead features?
Yes. Scalloped edges, decorative rolls and bosses are common on heritage dormers, but must be detailed to remain waterproof.
How should dormer aprons be installed?
They should extend 150 mm up the face of the dormer and lap 150 mm over the main roof covering, with joints properly lapped and welted.
Do dormers need patination oil?
Yes. Apply to exposed areas immediately after installation to prevent staining and ensure even weathering.
Next in the series (Post 14): Spire & Turret Roofing in Lead — advanced geometry, bay layout and decorative finishes.
