Sheet membrane roofing – seam separation/failure in PVC membrane

Separation or failure of seams can result in loss of weathertight protection and should be attended to without delay

Causes

Inadequate heat welding during installation

Expansion/contraction of the membrane 

Listed under: membranes, sheet membranes, plastic, polyvinyl chloride (PVC), Roof, cladding, roof cladding, sheet membrane roofing

Cause

Inadequate heat welding during installation

Repair

  • membrane manufacturers/suppliers typically train and license applicators in the use of their membranes. If repairs are made that are incompatible with the original membrane, the warranty may be void

  • if the roofing was installed relatively recently – within the last few years – call back the original installer. Roofs still under warranty should be repaired by the contractor who carried out the original membrane application. If the problem is the result of faulty design, specification or application (in other words, the membrane manufacturer is not at fault) the repair should be made at the cost of whoever carried out that work. If the original applicator is no longer around, contact the manufacturer or supplier of the membrane to find another approved applicator

  • application or replacement of roofing membranes is restricted building work. Where done by a tradesperson, it must be carried out or supervised by a licensed building practitioner with the relevant licence class for the type of roofing

  • if the problems mean the existing membrane must be replaced, and it has not met minimum Building Code durability provisions applicable (15 years), a building consent will be required

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Cause

Expansion/contraction of the membrane 

Repair

  • if there is expansion/contraction it is most likely caused by the expansion/contraction of the substrate, so potential a much harder problem to fix and not related to the membrane

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