Delamination of sheet membrane roofing from substrate

Cause

Incompatible membrane material was laid over substrate, such as rubber membrane over bitumen-impregnated membrane. The adhesives used in a rubber-based membrane are solvent-based and react with the oils in the asphalt, causing the membrane to separate from the asphalt

Repair

  • where the problem is extremely minor with no risk of leaks, watching to see whether it gets worse may be an appropriate first response. Where significant areas are not properly adhered, the membrane should be removed and replaced with a material compatible with the substrate

  • if the membrane was installed in recent years, call the installer back. Roofs still under warranty should be repaired by the contractor who carried out the original membrane application or by another applicator approved by the membrane supplier

  • installation and/or repair of membrane roofs is typically not a DIY job. Membrane manufacturers and suppliers typically train and license applicators in the use of their membranes. A warranty may only apply where application or repair is carried out by someone licensed by the supplier

  • work on roofs is restricted building work under the Building Act and anyone engaged to carry out this work must be a licensed building practitioner or be supervised by an LBP

  • check the condition of membrane roofs at least once a year to ensure there is no debris on the roof, no damage and no breakdown of the membrane surface

Cause

Poor installation

Repair

  • as above

Cause

Subsequent coats of liquid-applied membrane were applied before preceding coats have cured

Repair

  • as for first repair above