My client as contractor for a residential development has completed considerable additional works such as excavating up to 3m depth for foundations which was not included in the tender price. These additional works were not instructed and were necessary to comply with Building Regulations. The Contract Administrator was only on site 3 times in 3 years and the Employer having previously paid the additional costs is now saying that any variations must have been instructed.
It was not possible to get instructions and additional excavations were required due to poor ground for foundations and roads.
This is another difficult area. If your client undertook the additional dig without any form of acknowledgement of the CA then he is probably not entitled to recover the costs of the Variation or Change.
If the additional work was tacitly approved or was done with the knowledge and approval then there are potential arguments that it was instructed without compliance with the strict requirements of the Contract. In which case it may be possible to argue that there was some implicit amendment of the Contract that allowed informal instructions for Variations to be issued by the CA.
I would check the facts surrounding all of the extra works and the circumstances in which they may have been instructed.