AEW managing director Steve Burne today insisted that a £1.1m damages ruling in relation to its work at the Museum of Liverpool would not affect its ability to carry on trading.
The Manchester architectural practice has been successfully sued at the High Court by National Museums Liverpool over design flaws during construction of the museum in 2009.
Claims centred around problems with steps and an amphitheatre-style seating area at entrances to the building, some of which remain closed to the public.
There were also faults with a suspended ceiling, one of which collapsed and injured a workman.
A judgement issued by Mr Justice Akenhead recognised that one of the contractors, a joint venture between Galliford Try and Danish builder Pihl, was also partially responsible.
They have been ordered to pay £205,000 of the total £1.1m damages bill.
A separate judgement relating to the work on the ceilings is expected in several weeks, potentially leaving AEW facing further damages.
The museum had originally claimed for £3m in damages.
"We are disappointed with the outcome of the case," Burne said following the ruling.
"The matter is being dealt with by our insurers and does not affect the ongoing health of the business, but we take criticism seriously.
"We pride ourselves on outstanding levels of service, a fact borne out by over 95% of our business being for repeat clients.
"The management structure of the company has completely changed since the events of 2009 and we have moved in a different direction in the last four years."
The judge said the main fault related to the geometry used to construct an area known as the "valley" – where steps met seats in an amphitheater area on two sides of the museum.
The contractors had been building the area, but stopped, thinking the design was impossible and, instead, installed a "plinth solution" which the museum board objected to, describing it as an "abomination".
It led to the plinth having to be removed, at a substantial cost, and the amphitheater steps and seating areas at either end of the museum had to be boarded up and were not opened to the public.
In his summary the judge said: "The truth is that AEW knew and must have known by the October or November 2009 period that there had been a serious mistake and that it was simply not possible to achieve the practical and aesthetic effect required by the client and indeed by the planning permission which had been obtained
"It is simply extraordinary that competent architects could consider that it was acceptable to adopt the plinth solution in any event given their client's aspirations and wishes and, even worse, without seeking the informed approval of its client."
Sharon Granville, executive director of the Museum of Liverpool, said: "The court has found in favour of National Museums Liverpool on all counts.
"We are very pleased with the outcome.
"This financial award for the external works means that we will now be able to rectify the long-standing issues with the external steps and terraces at the museum and make them accessible to the public as soon as possible.
"We are grateful for Mr Justice Akenhead's decision and await the financial award for the ceilings inside the museum in a few weeks time."
Construction started on the museum, on Liverpool's waterfront, in 2007. It opened in 2011.