Do we need a 'Building Permit'
I get asked this question at just about every site assessment that I do.
The first thing I usually ask is "are we altering the structure of the building?" By this I mean are we changing or modifying the engineered components (bracing, moving load bearing walls, extending the structure, installing retaining walls over 1 meter tall, etc) if the answer is yes to any of these then you absolutely need a building permit.
Follow this link for more clarification
It is crucial to our industry that you follow protocol, this prevents sub standard building work as the work will need to be signed off by a Registered Building Surveyor (RBS) and ensured that it all complies with regulations and standards.
Don't be tempted to go with the Builder that goes against the above. Initially it may be cheaper, but usually the work fails and will ultimately cost you more to have it done correctly.