Independent pre construction tests

Is there any benefit in getting my own soil test, contour, survey and hydraulic designs?

I was hoping that armed with this information I could be more portable when getting tenders from builders, perhaps have the deal sweetened?

Has anybody done this with volume (or not) builders? Did it pay off in the end?

I had a few tenders done through various builders who each insisted on getting soil tests etc done themselves each time and would not even look at the previous. There was also a copy at council but again they wanted their own.

I think the reason is that should the classification be wrong and the builder has offered you a fixed price contract, they have no come back.

The other issue is you can get different results, our block has come back as an M, H and P in various reports. Each builder insists on using what their report specifies.

In W.A., most builders use the same company. We saved about 800 dollars by going through a builder as they receive a significant discount on the prices we were quoted to go direct. We came to an agreement with the builder that we could use those survey results with other builders to get quotes. As our site work costs are significant, this has been quite useful in comparing different builders site costs.