Lead Cornices & String Courses: Heritage Weathering Details
Horizontal weathering details like lead cornices and string courses protect masonry façades while adding architectural definition. This guide explains bay lengths, drips, fixings and decorative profiles in line with Leadwork Standards.
1. Code Selection
Code 5 lead is standard for cornices and string courses. Code 6 may be required where water run-off is heavy or detailing is complex.
2. Bay Lengths & Joints
Keep bay lengths to 1.5 m for Code 5 or 2.0 m for Code 6. Provide drips at joints to ensure water sheds cleanly away from the masonry face.
3. Drips & Overhangs
Drips should project at least 50 mm to prevent water running back onto the wall. The undercut should be sharp to ensure proper shedding.
4. Fixings & Integration
Lead is fixed to timber grounds or masonry using clips that allow movement. Care must be taken not to trap water behind the covering. Integration with string courses should align visually with façade lines.
5. Finishing & Maintenance
Apply patination oil to visible surfaces to reduce staining. Inspect joints and drips regularly, as blockages can cause water staining on façades.
FAQs
What lead code is best for cornices?
Code 5 is standard, with Code 6 used for larger or more exposed details.
How far should drips project?
At least 50 mm, with a sharp undercut to prevent water tracking back onto the masonry.
Do cornices need expansion joints?
Yes, joints should be provided at recommended bay lengths (1.5–2.0 m depending on code).
How are lead cornices fixed?
With clips to timber or masonry grounds, allowing for thermal movement.
What maintenance is required?
Regular inspection of drips and joints, plus reapplication of patination oil to reduce staining.
Next in the series (Post 19): Lead Balustrades & Copings — weatherproofing horizontal features on parapets and terraces.
