Sheet membrane roofing springy or spongy to walk on

Cause

Damage to the substrate and/or framing due to water entry through the membrane or through adjacent wall claddings 

Repair

  • check the roof structure from below for evidence or water leaks and substrate or framing deterioration or engage a well-experienced building surveyor to do this. The source of water entry must be clearly identified before any repair work begins

  • where leaks are through adjacent wall cladding, repairs must be made to the cladding as well as the roofing

  • in all cases where significant leaks are found, engage practitioners (building surveyor, builder) who have experience in identifying and remedying weathertightness problems

  • if the roof framing is sound but the substrate is damaged, the membrane and substrate should both be removed and replaced. The new substrate should be appropriate for the purpose, such as H3.2 CCA-treated, minimum 17 mm thick plywood. Ensure the recommendations and requirements of the membrane manufacturer are followed

  • 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

  • where the roof membrane has not proved to be weathertight for a minimum 15 years, a building consent may be required for the repairs

  • 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

The substrate material is not thick enough to span rafters/joists

Repair

  • as above. The substrate must be replaced with material thick enough for the spans

Cause

Particleboard has been used as a substrate and has deteriorated

Repair

  • as for the first repair. Particleboard is not suitable as a substrate in this situation and must be replaced with a suitable material