Weather has slowed evaluation of repairs or replacement, raising questions about exhibition games.
The winter punch that took down the Metrodome's roof is now threatening to mess with the start of the Vikings exhibition season in August.
This week's wind, snow and cold have hampered efforts to figure out whether the roof needs to be patched or replaced. Two workers on the roof Thursday morning who were examining the fabric were forced off by subzero windchills.
Those delays are adding pressure to a timeline that the Metropolitan Sports Facilities Commission, the Metrodome's landlord, may not be able to meet.
A key engineering report to help determine whether the roof can be repaired is not expected for two weeks. Officials have previously said that the stadium won't be usable through March.
"If we need complete replacement of the roof, it will take five to six months,'' Ted Mondale, the commission's newly appointed head, said Thursday.
While the NFL has not yet released preseason schedules, games usually begin in mid-August. The manufacturer of roof panels for the Dome has enough material to replace nine panels, which is more than enough to fix the five torn panels but not enough to replace the entire roof.
Mondale said the commission also would need to work out details of a replacement roof with its insurer, which could take time.
An engineer's evaluation of what needs to be done might be finished in the next two weeks, said Steve Maki, Dome facilities and engineering director. The roof analysis, which recently expanded to include examination of roof-cable connections and a more intensive look at roof fabric, has been plagued by weather-related delays.
"Wind, snow and the elements are not always our friend," Maki said. Until that work is done, he said, establishing a firm timeline for Dome repair is difficult.
"We don't know exactly what it's going to take to do the work, and there's the scope of the work as well as procurement issues," he said. "All of this is based on things that right now, we don't know."
Lester Bagley, vice president of public affairs and stadium development for the Vikings, said on Thursday that team officials and the NFL "have engaged an engineer who is also reviewing and analyzing the work. Until that is complete, we will have no comment."
The commission has told Dome users, including the University of Minnesota baseball team and other college teams, that there will be no events on the Dome field until at least the end of March. Mondale said he believes there will be no college games at all in the Dome this spring.
He said that his primary concern is safety and that he will not rush the work to evaluate or repair the roof.
"It's critically important to have an unhurried, unbiased view of this project," he said.
Mondale said the commission has not talked with the Vikings about the implications of a potential new roof on the exhibition season, calling it premature.
On Thursday, the commission approved a plan to replace an acoustic roof liner at the Dome's center with sheets of batting that will hang from roof cables to improve sound. The liner was removed from the Dome's center to allow heat to reach the roof faster, improving snow melt. The batting will cost an estimated $500,000, mostly paid by insurance.
The Dome's air-supported roof was torn in the Dec. 11-12 blizzard. Four panels were damaged by weather. A fifth was deliberately opened with a shotgun to relieve pressure from snow and ice.
The Dome's concourses reopened last weekend for skating and this week for running.
Mary Jane Smetanka • 612-673-7380