Chimneys, leadwork & roofline

What is a lead valley and why does it fail?

Short answer: A lead valley channels water where two roof slopes meet. Failure can result from splits, undersized laps, blocked flow, poor support or pieces that cannot move thermally.

What this means in practice

Chimneys, valleys, abutments, ridges, verges and eaves are where different materials and movements meet. Repairs must address the supporting masonry or timber as well as the visible lead, mortar, plastic or metal finish.

What to check next

  • Keep the water path clear
  • Use suitable lead code and bay lengths
  • Inspect tile cuts and surrounding underlay

When should you ask a roofer to inspect it?

Arrange close inspection for loose masonry, repeated staining around a chimney, split lead, detached verge units or gutters that still overflow after cleaning. Scaffold-dependent repairs should be grouped where sensible so access is not paid for twice.

Safety first: do not climb onto a roof without suitable access, training and protection. Keep clear of loose coverings, unstable ceilings and water near electrical fittings.

Technical content reviewJ & L Welch Roofing & Paving Services Ltd · Over 20 years of combined roofing experienceReviewed 28 August 2026 · How our answers are produced

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