Bottom plate overhang

Tuesday, 31 May 2016

In its Proactive Inspection Program, the VBA has identified a number of sites where bottom plates overhang the slab edge and have not been approved by the relevant building surveyor.

On one project, VBA inspectors observed non-shrink grout applied to the underside of the bottom plate and adhered to the side of the slab.  The bottom plate was overhanging the slab up to 40mm.

In the 'VBA Guide to Standards and Tolerance 2015', item 4.08 outlines that where a 90mm wide bottom plate overhangs the slab by more than 10mm it is considered to be a defect in workmanship.

Practitioners are reminded that the Guide to Standards and Tolerances is not an alternative to the design standards established in the National Construction Code and should not be the benchmark for demonstrating building work complies with the requirements of the law. Where the bottom plate overhangs the slab (including less than 10mm), the builder, site supervisor and/or building inspector should report these incidences to the relevant building surveyor for consideration.

Builders, building inspectors and building surveyors are reminded that where a bottom plate overhangs the concrete slab and rectification in accordance with the approved design is not practicable, any additional building work undertaken to provide support to the bottom plate must be designed, documented and approved by the relevant building surveyor before the building works are undertaken and the frame presented for inspection. An engineer is the appropriate registered building practitioner to provide a design solution.

When a practitioner finds there is bottom plate overhang, they should:

  • Rectify the building work to meet the design requirements of the relevant building permit
  • Where rectification is not practicable, discuss with the relevant building surveyor
  • Engage an engineer to evaluate the impact of the bottom plate overhang on other building elements, including the adequacy of the wall cavity where a masonry veneer wall is to be constructed
  • Document any alternative design proposal and ensure it is approved by the relevant building surveyor prior to the work being done
  • In the case of building inspectors, ensure that any repair work on site is in accordance with the approved alternative design solution.

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