Winter Construction Scheduling

Don't let weather dictate your sequence of operations.

Winter construction operations make for some untenable conditions that a scheduler must incorporate into his baseline network, or sequence of operations. This is not the same as a weather delay contingency. If he has done his research, he knows that productivity decreases with the temperature as much as 30%, and then factors that into activity durations. In cases where the schedule has slipped, weather constraints may come into play that were not anticipated in the baseline. This is especially so for fit-out trades, where productivity rates can be even lower.

Insofar as cold weather work, some trades are slowed more than others. Excavation of frozen earth can take far longer than normal conditions - especially for the manual workers. Concrete form work takes longer, and will require tenting and blankets.

It’s easy to say that productivity is off in cold weather, than to experience it. For example, last year, in an open deck tower on the East River, snow, ice, and blistering cold were lining our upper decks. With no temp heat, it was difficult to get any fitout done other than concrete and risers.

A fair amount of research is available on the subject of productivity and weather, as is a recipe for calculating your own productivity analysis.

Cold weather is also enemy to a whole smattering of materials requiring set temperatures above 55 deg F, including: waterproofing agents, paint and sealants, glues and adhesives, caulking, etc. Portland and other cementitious are less sensitive, but still require ad mixtures to generate heat. The rest will have to be put off until climatization.

Much equipment is sensitive to sub-zero temperatures, such as those with lubricated moving parts. When the wind reaches a given force, cranes and other rigs are not permitted to operate - disrupting major operations. If snow and ice or in the mix, time is lost in clearing as well as increased labor in the elements.

Buildings in progress might have the open decks wrapped with tarps, or not. They also might have temp heat, or not. At minimum, they will insulate and heat-trace all fire suppression and water pipe - especially at the valve assemblies. If the deck is available to trades to work, owner or SHs will expect the workforces to be going full-tilt, regardless of the weather conditions - caring little for productivity loss statistics (simply add more personnel). The workers work at the pace that is expected of them, and don’t complain too much about the weather.

A word to the wise is not to deliver, store, or install any raw are finished material or product that is subject to shrinking and swelling in non-climatized installations. Of course, there’s non-climatized, and extreme conditions to consider: you endeavor to have your product on site without exposing it to extreme environment: if the material or product deflects, swells, cracks, etc., as a  reaction to adverse conditions, the manufacturer warranty may become void.

If all you have is tarped off decks and some space heaters, you have minimal control of the heat and humidity. Sometimes you just have to bite the bullet and warehouse product until the building is climatized. It’s odd, that many luxury condo designers never think to include a humidity/dehumidifier system in their designs. All they need do is ask any engineer who understands what happens to finishes in arid and variable conditions - such as arid winter apartment interiors, and have them explain this to the buyers..

In New York City, there are regular annual embargos that limit operations such as crane erection and picks, deliveries, and street openings. It is always reasonable to have a lot of float in the above activities between the beginning and end of the embargo period. For example, if a crane pick is scheduled on the of the last embargo night, it could be sidelined by regulators -  a costly miscalculation.

Therefore, savvy schedulers and contractors know how to schedule work around the weather. They build in the extra time and activities into their timelines so that they are not unprepared for adverse conditions. They have the climatization, manpower, and sequence of operations at the ready for cold weather work. The other contractors who don't plan spend the winter holed up in their trailers.