The real reason the Hamilton Tiger-Cats' $145.7-million stadium is three months late is because of a major engineering miscalculation, according to two union officials.

Tim Hortons Field, which replaced aging Ivor Wynne Stadium and will also play host to the soccer competition for the 2015 Pan American Games, was not designed to support a capacity 24,000 crowd, say Tony DiMaria, business manager of the Brick and Allied Craft Union Local 1 in Hamilton and James Hannah, business manager of Ironworkers Hamilton Local 736.

The resulting work to fix the mistake plus poor construction scheduling by the builder, Ontario Sports Solutions (ONSS), meant increased labour, design and materials costs along with the delay. No one connected to the project would say how much this will cost, but officials with the City of Hamilton and Infrastructure Ontario, which oversees major construction projects for the province, say ONSS, not the taxpayers, must pay for it.

Story continues below advertisement

"All I can say is we're clean as far as the city is concerned," Hamilton Mayor Bob Bratina said.

Officials with ONSS, a consortium led by Bouygues Building Canada, a French company, and Kenaidan Contracting Ltd. of Mississauga, have blamed the delay on a severe winter, a masonry subcontractor going into receivership and, at one point, the length of time it takes to get building permits from the city.

"Somebody screwed up but are they going to admit it? No," DiMaria said, referring to the fact deciding the responsibility for any cost overruns will likely end up in court.

DiMaria and Hannah said the design mistake was discovered shortly after the ironworkers started work on the stadium last October. As a result, the structural steel, which is the framework of the stadium, had to be redesigned. Then new steel had to be fabricated and ordered.

Angle iron, called clips, had to be welded on the existing steel as reinforcement in many areas, contributing to the delay. Some concrete foundations also had to be torn out and repoured. This had a domino effect in delaying subsequent work such as the masonry, electrical and duct work.

Only a rush of last-minute work allowed part of the stadium to open Sept. 2 for a Tiger-Cats game against the Toronto Argonauts. It will not be substantially finished until Oct. 2.

Hannah said in conversations he had with union workers and others on the job site, he was told "they didn't allow for sway."

Story continues below advertisement

"Say you get the wave going and people are moving at once – they are going to sway," Hannah said, adding that under the original design there were concerns this kind of motion under the weight of 24,000 spectators would render the structure unsafe.

The city of Hamilton contributed $54.3-million to the $145.7-million cost of the stadium. In return it takes over as owner of Tim Hortons Field. The rest of the financing came from the provincial government, which paid $22.3-million, and the federal government ($69.1-million), as the stadium will play host to the 2015 Pan Am Games soccer competition. Infrastructure Ontario is withholding $89-million in payments from ONSS until the stadium is finished.

However, under its lease with the Ticats, the city is also responsible for paying the team $3-million in compensation for the three missed home games. City officials have indicated they plan to recover that money from ONSS or Infrastructure Ontario and go through the courts if necessary.

That is probably why ONSS officials were insisting the delays were for reasons beyond their control. Infrastructure Ontario vice-president John McKendrick, who oversees Tim Hortons Field plus two other Pan Am projects built by ONSS, dismissed those claims.

"Those are all risks Ontario Sports Solutions has to take," McKendrick said. "The [construction] schedule was always aggressive, but they signed up for it, they agreed to it. It's their responsibility to manage their subtrades, it's their responsibility to manage the design-build process, it's their responsibility to manage the fabrication of their steel. If you miss your dates after that, don't come to me and complain because it's not my problem, it's theirs."

All three of ONSS's Pan Am projects are behind schedule and still not finished. The consortium is also building the $56-million velodrome in Milton, Ont., and a $53-million athletics stadium at York University in Toronto for a total of $254.7-million. The velodrome and the York stadium were both overbudget at a total of $13.5-million so far.

Story continues below advertisement

Bouygues projects director Samuel Gandossi did not respond to requests for comment. Greg Stack, vice-president of business development for Kenaidan and the lead official for ONSS, declined to comment. He referred questions to Infrastructure Ontario.

McKendrick agreed the builder's poor scheduling contributed to the delay but played down the role of a design flaw in the structural steel. He said Tim Hortons Field is a design-build project, in which some of the structure's design is done as it is built, which can result in delays.

McKendrick also said he did not know if the failure to account properly for the weight of the spectators was the reason for the redesign of the structural steel. But both he and officials for the City of Hamilton, which approved the redesign and issued an occupancy permit for the Ticats game, said the stadium is now safe.

In a design-build project, McKendrick said, "you design the stadium while you are building the stadium. So you go through a process where you design and you test a lot and then you decide you need to make some modifications as you go."

However, since a contractor agrees to build something for a fixed cost and with a completion date, such modifications are normally taken into account. A contractor also comes to a design-build project with a basic design in place. DiMaria said the extent and the cost of the modifications of the steel at Tim Hortons go beyond what is normal for such projects.

"From the very beginning they knew they were going to have 24,000 fans; they didn't find out halfway through," he said. "You know you're designing a stadium, you know you're going to have 25,000 people sitting in it, so your structure of steel is already in your mind if you're an engineer.

Story continues below advertisement

"How can you underestimate that much, so you have to have cross-bracing put in everywhere and restructure the pillars? If they didn't have these major problems they wouldn't be three months behind."

In some cases, DiMaria said, concrete-block walls were repeatedly torn down and rebuilt because of poor scheduling.

"It's like when you build a house you don't call the plumber after all the walls are done and the floor is in and then start digging holes through the wall to find your piping," he said.

McKendrick agreed that scheduling was a big problem for ONSS on all three of its Pan Am projects.

"Some contractors and project companies are better than others at sticking to their schedule," he said.