Geoffrey Osborne is facing a £10m claim over a fire that destroyed part of a Sussex care home.
In papers filed at the High Court, Hyde Housing Association claims the contractor failed to comply with Building Regulations designed to prevent the spread of a fire.
Hyde alleges the Marlborough House care home (pictured) was unsafe and “not fit for human habitation” because the property was not sufficiently protected against fire.
The fire on 28 July 2013 started in a flat occupied by a resident described as having a history of hoarding and a large quantity of domestic goods in his home.
After the resident discovered a small fire in his sitting room, smoke spread to neighbouring properties before the fire broke through into the roof space of the property.
East Sussex Fire Service was called to the scene as more than 30 residents were evacuated. No one was reported injured but three residents were taken to hospital.
Hyde alleges that, had Osborne complied with its contractual and common law obligations, the fire would have been contained within the flat for 60 minutes or more, which it said would have enabled the fire brigade to contain and extinguish it.
The company added that this would have prevented further damage to the adjoining flats, the roof structure and the lower parts of the building.
Hyde does not hold Osborne responsible for the cause of the fire.
Osborne has denied that it was required to comply with the regulation in question.
Hyde is claiming costs of £2.06m for the immediate aftermath of the fire, including installing the roof structure and the first phase of remedial works, for which it appointed Faithdean and Eastwell Contractor Management & Claim Care.
A tender has been put out for the second and third phase of remedial works, which it estimates will cost around £7.8m.
The housing association is claiming further losses, including the costs of alternative accommodation for the residents, who are still living in temporary housing.
Osborne was selected to design and construct the six-storey care home in March 2001, in a contract worth £5.6m. It completed the project in July 2003.
Hyde Housing Association and Osborne declined to comment.