Under this option, the designer uses documented support from an appropriately qualified and experienced person or organisation to demonstrate Code compliance. The expert opinion may be a peer review (by a designer experienced in reconstruction of the relevant house type), a BRANZ appraisal or a producer statement.

Where an expert opinion is provided, it should include credentials with the documentation, including:

• details of the expert’s skills, qualifications and experience relevant to renovation of the particular house type
• additional relevant information about their knowledge and expertise
• whether they are registered on a statutory register or belong to a relevant professional organisation.

As building consent authorities are gaining a better understanding of the credibility of individuals and organisations, the option of expert opinion is becoming more widely used as a means of compliance. 

The BCA is not obliged to accept expert opinion and may challenge the expert’s credentials. In some instances, the BCA may accept the opinion for specific aspects of a proposal but require other forms of supporting evidence to assess for full compliance.

When to use this option

The use of expert opinion with renovation work may be to:

• provide an independent written assessment of the performance of the existing house with respect to a particular Building Code clause, for example, weathertightness 
• provide independent supporting evidence on material performance and durability via a producer statement
• peer review details and material selections by someone with recognised experience in renovation of the particular house type
• utilise specific structural design for bracing and beam sizing
• provide specific thermal design.