GLYNDON, Minn. — Shovels and snowblowers were put to work Thursday morning, Jan. 2, after the Dilworth-Glyndon-Felton School District sent out a call for workers to help clear snow from the roof of the district's high school in Glyndon.

The move was recommended by a structural engineer who felt recent heavy snow put the building at risk.

As an added precaution, the school district shut down all of its buildings through Friday, Jan. 3.

Last spring, the Fargo-Moorhead area learned the hard way that heavy snow and rooftops don't mix.

On Sunday, March 10, a number of roof collapses came to light after a storm dropped about 9 inches of heavy, wet snow in the area.

One collapse occurred at St. Francis de Sales Catholic Church in north Moorhead. Services at the church were canceled that morning due to the weather, which likely prevented a greater tragedy.

The portion of roof that collapsed was above a large community room that was built in the mid-1990s and which today has a new roof that was completed last June.

The rebuilt roof appeared to be holding up well Thursday morning, though it was still covered with snow from a recent storm that dropped between 12 and 17 inches of snow on the Fargo-Moorhead area.

The March snowfall that caused the collapse last year may not have been as deep in total inches, but it was a very wet, heavy snow, recalled Dennis Ouderkirk, parish secretary.

A recent test

Ouderkirk said a breakfast had been planned for the morning the roof collapsed last March, but cancellation of activities that day meant that instead of the parish center being full, it was largely empty, except for a piano, furniture and religious statuary.

According to Ouderkirk, the new roof has additional trusses for added strength, but just to be on the safe side, workers planned to arrive in the near future to clear snow from areas of the roof where it traditionally collects.

"This will be a good test," he said, referring to the recent snowfall.

A spokeswoman for Moorhead Area Public Schools said Thursday that a consultant was reviewing whether snow loads were a concern for district buildings.

The Fargo School District said crews had removed snow from some roofs since the recent storm and monitoring of snow loads was ongoing.

"All of our schools are designed with our winter elements in mind; however, some of our buildings have roof architecture or are impacted by the wind differently that cause us to monitor their roof more closely than others," said AnnMarie Campbell, a district spokeswoman.

The West Fargo School District has measured the snow loads on its buildings and there is no concern at present, said Heather Leas, a district spokeswoman.

"Since we are so early-on with winter, we do have crews coming in next week to remove snow on roofs that are reaching load capacity, so it does not become an issue after the next snowfall," Leas added.

A spokesman for a company that sells sensors that can warn when a roof is failing said such failures often result from a number of factors, not just one, such as a large snowfall.

Chris Collings, who is involved with product design and sales at Safe Roof Systems, a Massachusetts-based company, said even a relatively moderate snowfall of, say, 6 inches can turn much more serious if it's followed by rainfall that saturates the snow and significantly increases its heft.

It is during those times a company like SRF can play a crucial role, according to Collings, who said sensor systems the company installs measure joist deflection, which provides early warning when roof sag reaches the danger point.

Collings said SRF has worked extensively in the Northeast region of the country installing systems on school buildings and other structures, though he said it is increasing its presence in the Midwest, including an installation in Belcourt, N.D.

A basic installation can cost in the neighborhood of $12,000, but depending on the size of a building the price can be upwards of four times that, according to Collings.

He added that many customers come to SRF after experiencing a structural failure due to snow, so they already know how costly it can be to have a roof cave in.

Important as it is to know when snow is causing a problem, Collings said it can be just as important to know when it is not, so a business or school doesn't have to pay to remove snow that isn't a danger.

Snow removal, he said, can "annihilate" a school district's budget.