Durham Crown Court heard how Walter Thompson (Contractors) Limited (WTL) was Principal Contractor for the 47 bedroom extension of the Ramside Hall Hotel in Durham.
During the installation of concrete floor slabs a worker was struck in the jaw by a crowbar when it became trapped between two of the slabs.
He suffered a head injury, including lacerations to his head and jaw and dislocated teeth.
An HSE investigation into the incident, which occurred on 15 December 2014, found that WTL failed to adequately plan and manage the installation of the two floor slabs.
Walter Thompson (Contractors) Limited, of Northallerton, pleaded guilty to breaching CDM Regulations and was fined £33,000 with £12,552.81 costs.