A shutdown order for Boston’s construction sites is likely to place strains on developments’ financing packages as developers struggle to meet investors’ timelines to make progress.

On Monday, Boston Mayor Marty Walsh announced that the city’s previously-booming building sector would go on hiatus today as part of attempts to slow the transmission of the coronavirus. There are nearly 130 active construction sites for new developments in the city, according to Boston Planning and Development Agency data. They range from small neighborhood housing projects to skyline-changing towers such as the 1.3 million-square-foot Winthrop Center tower expected to employ 2,800 construction workers by the time of its estimated completion in 2022.

Delays could have a cascading effect on many projects’ financing packages, said Brian Cook, an attorney at Goodwin Procter in Boston. Delays caused by government orders could invoke force majeure clauses in contracts, which excuse parties from being unable to complete certain milestones because of unforeseen circumstances.

“In those situations, there’s certainly going to be an argument and dispute whether this constitutes a force majeure that would excuse the performance of one side or another: the contractor’s obligations to the developer, the developer’s obligations to the lenders, and going back in the other direction as well,” Cook said.

Affordable housing projects could face a crisis similar to 2009, when the low-income tax credit market collapsed and Congress stepped in to offer gap financing to developers.

One local affordable housing developer, who asked not to be identified, said any delays could trigger penalty clauses in one of the company’s current projects. Like most affordable housing projects, the financing package relies heavily on federal low-income tax credits which are converted into equity by investors, in this case a large multinational bank.

But if the project misses deadlines for completion and occupancy, that could trigger a reduction in the investor’s equity contribution.

“We’re coming up against a deadline and even a couple of weeks can push us too far. We can face these downward adjusters, the investor gives us less equity, the project is in the red and we’re on the hook for it,” the developer said.

The construction ban does not apply to essential services such as emergency road building work, new utility connections to occupied buildings, mandated building or utility work, work at health facilities and temporary shelters, work to ensure the reliability of transportation and work needed to keep residential buildings habitable.