RENO/TAHOE - Single-digit temperatures and frozen ground are wreaking havoc on construction schedules across northern Nevada.Sub-freezing temperatures and record lows froze activity at construction sites from Lake Tahoe to Elko, forcing contractors to scramble to meet deadlines and oftentimes delaying crucial first-quarter revenue.In Truckee, where temperatures routinely dip well below zero, Clark & Sullivan Construction of Sparks is building an 8,500-square-foot clubhouse at Shaffer's Mill golf course. Superintendent Steve Jessup is forced to heat the lock to the job trailer with a hand-held blowtorch to gain entry in the mornings.In Sparks, where Gradex is performing site work for a new Maverick gas station at Legends at Sparks Marina, crews have had to work seven days a week to counter time lost to the cold.Gradex Superintendent Tony Evans says freezing temperatures affect nearly every aspect of site work."The impact is tremendous," he says. "You need water to mesh with the material, the dirt, to get it to compact. You are between a hard spot and a rock, really, because once your materials are compacted, overnight it freezes and it gets thicker and thicker."And in Elko, where nighttime temperatures are among the coldest in the state, work basically came to a standstill, says Q&D Construction's Lance Semenko, who heads the company's general engineering division.Frozen fill isn't the only problem with performing site work when temperatures hit single digits at night, Evans says. Last week crews were backfilling the concrete foundation with gravel to ready for a concrete pad, but the gravel had frozen into large piles and caused problems with the conveyor used to spread the material.Gradex also had to remove several yards of already-placed and compacted fill dirt because it had frozen solid and couldn't be worked."We either had to take it out and start with non-frozen material, or wait for it to thaw," Evans says. "The schedule on this project doesn't allow us to let it thaw. We got a foot of fill in, but it froze on us and we had to pull it out and start over - you can't place fill on frozen ground, because eventually it will thaw and you will have issues with unstable soil."To make up for missed time, contractors must to plan diligently and organize schedules with caution, beef up work crews, and work overtime to get as much work done as possible on warmer days, Evans says.That's how Clark & Sullivan beat the winter and enclosed the Shaffer's Mill clubhouse before snowstorms shut down work, says Project Estimator Doris Kelly.Construction routinely halts in the Lake Tahoe basin from October 15 to May 1, but Indian summers the past two years allowed contractors to capitalize on late-season warm weather. Clark and Sullivan had Truckee subcontractor Al Pombo work on the project upwards of 60 hours a week, and Pombo's crew performed site work until November under extension and gained about a month on the overall project schedule."We were able to get all the underground utilities and site work done," Kelly says. "Once the snow melts we won't have much time to get the landscaping, irrigation and sidewalks and paving done."Clark & Sullivan began work on June 14 and expects to be finished in early July - weather permitting. Since the building envelope was sealed prior to winter - the roofing contractor completed his work one day prior to the first snow - crews are now working inside completing interior treatments. Overtime may again be in the cards this spring if the snow lingers, Kelly says.Cold has all but shut down work in the Elko region, Q&D's Semenko says. Weather may delay crucial schedules, but project owners and contractors typically agree on days forfeited to weather aren't consider working days and therefore don't count against a company's allotment of scheduled work time."The weather really is not affecting the jobs because we are not working on them," Semenko said last week. "We haven't worked on stuff in Elko in a couple days."Reno-Sparks workmen stationed in Elko either have the option of staying in town at their own discretion or making the long drive back to the Truckee Meadows to spend off days with their families.Q&D's largest local job, pouring concrete along the Highlands Canal for Truckee Meadows Water Authority, also has been slowed due to the cold weather. Semenko says the delays can cause logjams in subsequent quarters."Things that were supposed to be done in the second quarter now show up in the third quarter, where we might have quite a few things that need to get finished," he says. "We might have to ramp up with additional men and machinery."