New claim over alleged design failings is believed to be one of the biggest in construction history

Multiplex has launched a £253 million writ against contractor Mott Macdonald, thought to be one of the largest in construction history, for alleged failings in the construction of Wembley Stadium.

Multiplex, now owned by Brookfield, has accused Mott MacDonald of failing to prepare a robust plan for the steelwork design, which forced numerous later changes to the plan.

The writ, which runs to 600 pages, is the latest fall out from the tortured construction of Wembley Stadium, which finished £300m over budget and has already triggered a protracted legal battle between Mulitplex and its steel contractor Cleveland Bridge.

Multiplex argues that work on the 90,000 seater stadium was severely delayed, overrunning by more than a year, and did not finish until March 2007, which meant it had to pay liquidated damages of £20.4m to owners Wembley National Stadium. The huge project should have been finished by January 2006, and Multiplex had hoped to win a bonus for early completion, the court will hear.

Multiplex accuses Mott of failing to provide an adequate erection sequence for the stadium, which incorporated a steel arch, a fixed steel roof, and a moving roof over the bowl which formed the seating and concourse areas.

Mott failed to warn that the arch would not be able to cope with temporary stresses caused by arch members during roll up, failed to carry out analysis to take account of temporary restraints to permanent structures, and failed to consider the effect of disproportionate collapse on temporary loadings and structure, it is alleged.

Multiplex claims that Mott failed to warn of design changes which would affect assumptions in the cost plan, and failed to design steelwork which could be build within budget. The engineers are said to have failed to reply to numerous technical queries and requests for information flagged up by steelwork contractors, and of making many late design changes, then charging extra fees for correcting deficiencies in its design.

If Multiplex had known that the design was incomplete, inadequate and complex during the project, it could have taken more effective steps to change the sequence of work, the writ claims.

Multiplex’s claim includes £132m for the increased cost of steelwork, £30.6m for the increased cost of the mechanical, engineering and plant work which followed, and £21m for other increased costs.

The construction company is also demanding £6.1m for loss of bonus as a result of critical delay to the project, £12.7m for loss of opportunity as a result of delays and disruption, and £2.6m for legal costs as a result of litigation with subcontractors.

Multiplex is also seeking repayment of £2.7m paid to Mott for alleged overpayments, £7.6m for the increased cost of trades which were affected by the steelworks, and £14.2m for the loss of a chance to tender for the demolition and construction contract on terms which reflected the steelworks’ true complexity and level of risk, or not to enter into it at all. The original contract was for a fixed price of £445m.

A Mott MacDonald spokesman admitted Multiplex had submitted a claim against the Mott Stadium Consortium (MSC) alleging breaches of contract in relation to the structural engineering design work on the contract. He said: “We would point out that Brookfield assumed responsibility for designing and building the stadium. We are in no doubt that MSC performed its obligations to Brookfield professionally and diligently. Mott MacDonald emphatically denies any liability for Brookfield’s loss and will vigorously defend the claim.”

He also said the figures mentioned in the claim were “not credible.”

The lawsuit was filed in court by solicitors Freshfields Bruckhaus Deringer.