Lead alternatives: when they work and when they don't
Lead substitutes exist for real reasons: cost, weight and theft. They are not a universal replacement for milled lead.
Why substitutes get specified
Lower material cost, much lighter to handle, and no scrap value, which matters on properties where lead theft is a recurring problem.
Where they perform reasonably
Simple, straight abutments on modern properties, small aprons, and utility structures. On low-detail work fitted correctly they can give good service.
Where they don't
Complex chimney step-flashing, valleys, deep pitch changes and anything requiring intricate dressing. Substitutes don't hold a dressed shape the way lead does.
Self-adhesive flashing tapes
Legitimate as a temporary or emergency measure. Used as a permanent fix over a failed lead detail, they lift at the edges and become the next leak.
Character and conservation
On period properties the visual difference is noticeable and local planning guidance often expects like-for-like lead. We default to Code 4 or 5 milled lead there.
FAQs
The material is cheaper. Whether the job is cheaper depends on the detail — complex work in substitute often takes longer and lasts less.
Substitutes on vulnerable low-level details, security marking, and physical restriction of access all help.
As a make-safe while a proper repair is scheduled, yes. As the repair, no.
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