Roof flashing buckled

Metal flashings need to stay firmly in place to play their role in keeping a building weathertight

Causes

Fixings prevent thermal movement

Lengths of flashing are too long – there are not enough joints, so insufficient thermal movement allowance

The use of rivets instead of screws prevents thermal movement

Listed under: metal, Roof, flashings, framing, moisture, fixings and hardware, fixings, weathertightness

Cause

Fixings prevent thermal movement

Repair

  • remove existing fixings; enlarge fixing holes and replace fixings with new waterproof washers and fixings; ensure that the new washers and screw caps cover the enlarged fixing holes and are securely fastened

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Cause

Lengths of flashing are too long – there are not enough joints, so insufficient thermal movement allowance

Repair

  • replace buckled sections using shorter lengths of flashing. Flashing lengths must be no more than 3 metres long, with 150 mm minimum laps. Seal each edge of a lap with neutral-cure sealant and screw-fix to the framing

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Cause

The use of rivets instead of screws prevents thermal movement

Repair

  • replace rivets with screw-fixings and ensure that fixings penetrate the roof framing

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