Unfortunately it is all butt covering. The exercise is how do...

Unfortunately it is all butt covering. The exercise is how do they apply safety factors. A safety factor is two parts. One - to have the structure safely endure now and into the future. And two - allow the engineer to sleep at night.

There are two distinct methods to achieve these outcomes. The first is to design in a nett manner without safety factors and then add the safety factors. And then if happy, sign off or add a butt covering margin. The second method is to do a calculation and add the safety factor, then the next calculation and add a safety margin etc until the end result which gets a safety margin and the butt covering safety factor. Some people should never be an engineer.

I have seen it with mesh in a panel. The initial calculation with the safety factor has one size mesh just missing out. An engineer using common sense will use the lower size knowing that the safety factor well and truly covers any shortfall. Another engineer will use the higher size. Some butt covering engineers will even use the next higher size mesh.

We have on numerous times taken builders and developers aside and said that if they want to save several hundred thousand dollars on the project, change your engineer and redesign.