Building a spiral staircase involves some tricky math. And building a double-helix staircase on its original footprint in a century-old lodge is even trickier.

Over the past year several local craftsmen have been involved in creating a replica of the twin circular staircases that once connected the lobby to the lower lake level in Many Glacier Hotel.

In the late 1950s the staircases were removed and the space was used to create a gift shop. The area below the staircase left enough room to build a stage that was used for variety shows and musicals through the decades.

The National Park Service’s goal in restoring the hotel, built in 1914-15 on the shore of Swiftcurrent Lake, was to restore the hotel to its original grandeur.

Work on the Many Glacier restoration has been a seven-phase plan orchestrated over the past 15 years, with significant components completed in 2005 and 2012. A year ago a $13.5 million contract was awarded to Swank Enterprises for the remaining improvements.

Overall, $42 million has been invested in the hotel restoration. One of the first projects involved lifting up the five-story building to straighten the sagging lakeside walls.

While the double-helix staircase is among the final pieces of the project, it is being funded with money raised by the Glacier National Park Conservancy. The nonprofit raised about $375,000 for the staircase and the installation of Asian-style lighting that also was part of the original décor.

Northwest Cabinet Works of Kalispell was hired to build the double-helix staircase. The company has a longstanding relationship with Swank, and owners Tony Dawson and John Hale have completed a wide variety of woodworking projects through the year.

When the project manager asked Northwest Cabinet Works to head up the project, Dawson wasted no time in tapping someone with special expertise in building spiral staircases.

“I knew if we were going to be a part of it, we’d need to bring on additional expertise,” Dawson said. “That’s why I called my friend Zane.”

Enter Zane Smith, a Kalispell woodworker who specializes in spiral staircases. Smith worked with Dawson’s draftsman to design a staircase that would fit in the original space, a task easier said than done.

“It was challenging, but fun,” Smith said, explaining that the biggest requirement was creating a staircase that could meet today’s safety codes and still fit in the same space.

“Once they peeled the carpet away in the gift shop, there was the footprint,” Smith said. “We tried to keep it as close to the original as possible.”

At first the craftsmen were working off historic photographs to envision how the staircase would be laid out.

“Throughout the whole bidding process we commented it sure would be nice if we had the original drawings,” Dawson said.

After a couple of earlier newspaper stories explained the staircase restoration, Dawson got an email from Stephen Smith, a local mechanical engineer who is “a walking encyclopedia” of Glacier Park.

Lo and behold, Stephen Smith had those original drawings. His company had done some engineering work in the park and through that process he had acquired the 1914 schematics for the staircase.

Dawson brought in his 83-year-old father, Bill Dawson, a retired ironworker, to tackle the welding of 3.3 tons of steel that created the skeletal structure of the unique staircase.

“He’s amazing,” Dawson said about his father’s expertise.

The steel stringers were ordered from a Chicago company that rolled the stringers into the exact radiuses needed. Bill, with help from another welder, then welded on all the parts while Smith directed the positioning and angling.

Bringing the double helix to life once again has been a collaborative effort from the get-go.

“Tony and I have worked as a team,” Smith said.

The steel structures were transported to Many Glacier Hotel in recent weeks. The elder Dawson’s handiwork will be covered completely with wood once the staircase project is complete.

Smith is now busy with the woodworking needed to complete the staircase. He’s using local fir, since it’s believed that’s the kind of wood the original staircase was made of.

The original staircase was made entirely of wood, but that wasn’t practical in this day and age.

With the regulations and codes, it would be very difficult to build in wood and support the kind of loads required for today’s engineering,” Dawson said.

Northwest Cabinet Works also is providing handrails and decorative pickets on the railing that will encircle the double-helix spiral.

The remaining renovations are on track to be completed by June 9, Glacier Park spokeswoman Lauren Alley said. The staircase is scheduled to be completed by the end of June.

Many Glacier Hotel will open for the summer season on June 15, reborn to welcome guests for another century.

Features editor Lynnette Hintze may be contacted at 758-4421 or lhintze@dailyinterlake.com.