New roofs

Should all old roof timbers be replaced during a reroof?

Short answer: No. Sound structural timber can normally remain. Decayed, undersized or damaged sections should be identified and treated through a clear allowance or agreed variation.

What this means in practice

A reroof is a complete weatherproofing system, not simply a new layer of tiles. The quotation should join up the covering, underlay, graded battens, ventilation, insulation, ridges, verges, leadwork, timber repairs, scaffold, waste and compliance route.

What to check next

  • Do not pay to replace sound timber without reason
  • Ask how hidden defects will be priced
  • Structural concerns may need an engineer

When should you ask a roofer to inspect it?

Ask for a full roof survey when defects are widespread, repairs keep moving from one area to another, the underlay is failing or the cost of repeated access is becoming uneconomic. The roofer should show why replacement is justified and separate confirmed work from hidden-work allowances.

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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