I have started this thread due to the increasing use of Alternative Solutions by volume builders and also because most people don't appear to understand how the National Construction Code (NCC) is structured. All too often I see posters erroneously referring to the Australian Standards as being the required tolerances and even referencing 'Guides' published by industry and regulatory bodies.
I have also started this thread to invite those with detailed knowledge and experience with Alternative Solutions to share that information with others so that new home buyers are better informed about any Alternative Solutions that their builders use. To better assist others, I suggest that you clearly head the builder's name and give as much detail about the Alternative Solution as possible. If you have opted out of using an Alternative Solution, also list the cost involved to do so.
REGULATORY BACKGROUND
The National Construction Code (NCC) comprises the Building Code of Australia (BCA) Parts 1 and 2 and the Plumbing Code of Australia (PCA) Part 3.
The BCA is a 'performance' and hierarchical based document as can be seen below.
The BCA performance requirements are on level 3.
Level 4a states Deemed to Satisfy Provisions and this will include referenced Australian Standards. Standards Australia is a private company and unless an Australian Standard has been legislated, it has no legal standing unless it is specifically referred to in a contract. The level 3 BCA has hierarchy over Australian Standards.
Level 4b states Alternative Solutions. A builder only needs a recognised 'expert' to document an Alternative Solution but that Alternative Solution also needs to be certified as complying with the BCA level 3 Performance Requirements. This can be achieved even though any stated minimum tolerances are not met. Once certified, an Alternative Solution can be used by the builder who commissioned its documentation.
Most Alternative Solutions certified by volume builders are used as cost cutting measures or to make allowances for tradies not performing workmanship that is compliant to stated requirements but some alternative solutions are formulated to overcome difficult design situations or to allow a better design outcome but which will still be outside of the minimum standards stated in the BCA or the Australian Standards.
The Victorian Building Authority (VBA) document linked below addresses Alternative Solution certification and the role required from the Relevant Building Surveyor (RBS).
http://www.vba.vic.gov.au/__data/assets ... tation.pdf
To get the ball rolling, some suggested Alternative Solutions that you can post information about (if still applicable) are:
Porter Davis
Water resistant finish allowed to some wet areas in lieu of water proofing.
Carlisle Homes
Water resistant finish allowed to some wet areas in lieu of water proofing.
Increased frame overhang allowance.
Mortar mix allowed to have more sand.
Henley Homes
DPC allowed to setback a max of 20mm from the outer face of mortar.