Wright raised concerns about his co-workers' cannabis use and while James said those allegations were established, he could not dismiss all of them, because that would leave him with no painting team to complete the project, the authority said.
But keeping Wright, James said, would cause disruption and potential resignations.
When it was later confirmed Wright no longer had a job, he challenged the fairness of the decision.
The authority said the decision was not communicated to Wright in writing.
In its determination, the authority said Maiden Construction failed in its good faith obligations to Wright.
It said Maiden did not:
• identify specific concerns or put them to Wright for consideration before the disciplinary meeting
• document the investigation
• disclose the results of his investigation prior to or during the final meeting
or allow Wright any opportunity to get advice or indeed to provide an explanation of any mitigating factors prior to issuing the decision to summarily dismiss.
The authority said after just a week of employment, Wright was provided no opportunity to reflect upon or address the concerns of his co-workers that he was "incompatible" - and they were not specifically put to him.
Maiden had also failed to check Wright's employment status and the fact his contract contained no 90-day trial provision.
In finding Wright was unjustifiably dismissed, the authority said he was entitled to compensation because he was afforded no dignity and suffered significant humiliation.