Method 1 - DtS (Deemed to Satisfy) by Expert Judgment
The Governing Provisions of the NCC part A2G3, clause (2)(b) permit certification as “DtS by Expert Judgement” whereby a substantive expert certifies that the product and/or installation fulfils all DtS requirements but is not precisely as specified in the code e.g., in AS3500.3.
For example, the Dam Buster rainhead is already pre-designed in accordance with Appendix I, Figures I2 and I3, of AS/NZS 3500.3, however, the rainhead is considered to be DtS by Expert Judgement because it differs in construction from Figure I2 due to the (fully tested and certified) front overflow chute.
Documentary proof that Dam Buster products meet the DtS by Expert Judgement and also the Performance requirements of all volumes of the NCC can be easily found on the Technical Downloads Page.
NOTE: if the above approach is not acceptable to either the relevant Regulatory Authority or the Building Surveyor / Certifier, then a Dam Buster Rainhead located at the end of a straight box gutter can instead be certified under a Performance Solution using Dam Buster’s Performance Solution templates and Evidence of Suitability documentation.
Method 2 - A Combination of Solutions (if required)
If required by the local regulator or otherwise deemed appropriate, a 'combination of solutions’ i.e DtS and a Performance Solution can also be used for all genuine Dam Buster devices.
In this situation, the box gutters themselves are DtS and must be designed by the plumber in accordance with Appendix I, Figure I1 of AS/NZS 3500.3.
The Dam Buster device/s and the design are then certified as a Performance Solution using the Templates and Evidence of Suitability documentation which can be very simply downloaded for free from our Technical Downloads Page.
A suitably qualified expert should devise a suitable Performance Solution where Dam Buster's products require certification under Method 2. Unfortunately the local requirements for this do vary from state to state and can cause confusion. In Victoria, a licenced plumber is considered a suitable expert, but please check with your relevant regulator for additional clarification if needed.