They help to ensure that homes are designed and built appropriately to ensure weathertightness, allow BCAs to make decisions about consenting and compliance, ensure that all parties in the design and construction process are aware of their responsibilities and protect contractors if legal claims are made after construction is completed.

First, a solid base of detailed plans and specifications is important to ensuring that appropriate designs, materials and construction techniques are used. Detailed and accurate building consent application, contracts and site records are also important, as are records of all contract variations and other instructions received.