Tesco is claiming that the supermarket was unfit for use because Costain failed to include proper fire protection. It further claims that Costain deliberately failed to report the fact in an inspection it carried out in 1993, three years after the store was built.
The fire broke out on 4 August last year and destroyed part of the store. It is understood to have started in a back office during extension work by another contractor. Foam insulation in a wall cavity is believed to have been ignited by a welder's torch.
Tesco has also issued a writ for damages against the store's architect, Birmingham-based Peter Hing and Jones.
The supermarket chain claims the architect failed to design the store properly or supervise the works. It also claims that the store was not built to the specifications in the building contract, and did not conform to standards of good building practice.
The High Court writ states that the supermarket did not have proper protection against the start or spread of fire, because it lacked effective fire barriers, fire stopping measures, or effective fire breaks.
The writ also claims that there was no effective cavity closure at the top of outside walls and no effective divisions in the extensive roof voids. It alleges that flammable building materials were used in construction of the store, and that the contractor failed to comply with relevant building materials regulations.
In addition, Tesco accuses Costain of negligence and breach of contract when carrying out a detailed inspection of fire barriers at the supermarket in 1993. It alleges that the inspection – by Costain Construction and Costain Engineering and Construction – was carried out incompetently.
In October 1993, the two Costain companies apparently confirmed that the fire-stopping works at the store complied with the requirements of the design, and with the statutory regulations prevailing at the time.
However, Tesco argues that the works did not comply with these statutory requirements, and that the two Costain companies concealed the true position from the client.
Tesco claims that because of Costain's negligence, breach of contract and negligent misstatement, and also the failings of the architect, the fire at the store spread rapidly.
A Tesco spokesperson confirmed that the firm was taking action over alleged negligence. The action is being handled by the group's insurers.
Costain and Peter Hing and Jones said they were defending the action through their insurers.
Tesco first launched the action at the start of this year, but has now followed it up with a letter detailing the claim.