Waterproof decks – seam separation or failure

Cause

Inadequate heat welding during installation

Repair

  • for PVC membranes, lift and clean the seam; re-weld with a hot air gun
  • for synthetic rubber membranes (butyl), lift and clean the seam; re-adhere with an adhesive or lap tape recommended by the manufacturer 
  • check with the roofing manufacturer before re-adhering the seam as some adhesives are not suitable for use where the joint is continuously wet; if ponding is a problem on the roof, see 'Water ponding'. 
  • where it is suspected that the building may be leaking and there is a risk of damage, engage a building surveyor to report on the building and advise on repair/replacement options

Cause

Loss of adhesion at the joint

Repair

  • for PVC membranes, lift and clean the seam; re-weld with a hot air gun
  • for synthetic rubber membranes (butyl), lift and clean the seam; re-adhere with an adhesive or lap tape recommended by the manufacturer 
  • check with the roofing manufacturer before re-adhering the seam as some adhesives are not suitable for use where the joint is continuously wet; if ponding is a problem on the roof, see 'Water ponding'. 
  • where it is suspected that the building may be leaking and there is a risk of damage, engage a building surveyor to report on the building and advise on repair/replacement options

Cause

Expansion/contraction of the membrane

Repair

  • for PVC membranes, lift and clean the seam; re-weld with a hot air gun
  • for synthetic rubber membranes (butyl), lift and clean the seam; re-adhere with an adhesive or lap tape recommended by the manufacturer 
  • check with the roofing manufacturer before re-adhering the seam as some adhesives are not suitable for use where the joint is continuously wet; if ponding is a problem on the roof, see 'Water ponding'. 
  • where it is suspected that the building may be leaking and there is a risk of damage, engage a building surveyor to report on the building and advise on repair/replacement options

Cause

Water has got under the membrane causing a breakdown of the adhesive

Repair

  • where it is suspected that the building may be leaking and there is a risk of damage, engage a building surveyor to report on the building and advise on repair/replacement options