Major construction projects across Quebec are on hold indefinitely after unions representing 175,000 construction workers launched a general unlimited strike following months of failed labour negotiations.

Labour federations and construction companies negotiated late into the night Tuesday, but were unable to reach a deal before a midnight strike deadline.

Workers in the industrial sector are asking for more stable work schedules, while salaries are believed to be the main sticking point in the residential sector.

"Employers are asking us to sacrifice time with our families to be available for work," said Michel Trépanier, spokesperson for the alliance of construction unions. "There are limits and they've been reached."

Their collective agreements expired April 30.

Some striking workers went to different sites to ensure the strike was being respected. (Paul Chiasson/Canadian Press)

Hundreds of workers picketed Wednesday at the work sites for the new Champlain Bridge and the CHUM hospital, two of the big projects underway in Montreal, a city replete with orange construction cones.

Work on the new Turcot interchange, a key stretch of highway in the city's west end, will also be disrupted, a union spokesperson said.

In addition to picketing, some striking workers visited other construction sites to ensure all workers had put down their tools.​

Plumber Martin Gauthier said he is in favour of the strike but hopes a deal will soon be negotiated.

"I'm not making money today," he said, adding that the strike was also costly for employers. "Nobody is winning — that's the bottom line."

Large and small construction projects across the province are affected by the strike. (CBC)

Construction workers aren't the only ones on the picket line today. Roughly 1,400 Quebec government engineers also walked off the job at midnight.

The government engineers have had a strike mandate for almost a year, and their union president, Marc-André Martin, said a week of negotiations has ended without notable progress.

No back-to-work legislation for now

After meeting with both parties Wednesday afternoon, Quebec Labour Minister Dominique Vien said she's hopeful construction workers and their employers can reach an agreement quickly.

"The message I want to send is that it would be better to have a negotiated deal than a special law," said Vien. "I think that everyone here very much agrees with that."

But she stressed that the province is prepared to table back-to-work legislation if necessary, adding that a walkout could mean losses of $45 million a day for the Quebec economy.

"Of course, the premier said it and I'll say it too that we won't allow a strike like this to continue, because it's too costly for Quebec, for the Quebec economy and for Quebec families," said Vien.

175k Quebec construction workers on strike. Want better work-life balance & better schedules. Gov't might rule them back to work. <a href="https://twitter.com/hashtag/polqc?src=hash">#polqc</a> <a href="https://t.co/7fswhqVYAc">pic.twitter.com/7fswhqVYAc</a> —@TurnbullJay

Montreal Mayor Denis Coderre, whose administration has poured millions into construction projects for the city's 375th anniversary, urged the province not to be "too patient" before stepping in.

He said the strike has a major impact on the city, and he hopes that the parties will reach a deal as quickly as possible.

"We're not going to be patient for a long time," said Coderre.

In Montreal, about 60 city projects have come to a complete stop as a result of the strike.

Quick settlement needed, business group says

Employer groups have said the province's anti-strikebreaker law does not apply to the 175,000 construction workers.

This is the second general strike in the Quebec construction industry in four years.

Work schedules and overtime are some of the key sticking points in negotiations for construction workers in the industrial sector. (Simon-Marc Charron/Radio-Canada)

The federation that represents chambers of commerce in Quebec also called for a rapid end to the dispute.

"The adage that says 'when the construction industry is doing well, everything is doing well' is also inversely true — a labour conflict has a major and direct impact on all economic sectors," said Stéphane Forget, head of the Fédération des chambres de commerce du Québec.

Workers picket outside the CHUM hospital in downtown Montreal. (Simon-Marc Charron/Radio-Canada)

Forget noted the 10-day work stoppage in 2013 resulted in a drop of 1.1 per cent in the province's gross domestic product.