As design professionals working within the construction industry, we have had to find ways to adapt to the fact that, at least several (if we are lucky) months of the year we will have to deal with wintery conditions.
Good detailing, tight specifications, and proactive construction precautions can allow construction to take place even when the weather conditions are less than ideal. Throughout the ages a primary concern of architects, and builders has been the integrity of their creations.
This article will leave “venustas” for a later time, and focus on the Firmness and Utility of buildings as they relate to cold weather construction.
“Writing near the end of the first century B.C.E., Roman architect Vitruvius Pollio identified three elements necessary for a well-designed building: firmitas, utilitas, and venustas. Firmness or physical strength secured the building's structural integrity. Utility provided an efficient arrangement of spaces and mechanical systems to meet the functional needs of its occupants. And venustas, the aesthetic quality associated with the goddess Venus, imparted style, proportion, and visual beauty. Rendered memorably into English by Henry Wotton, a seventeenth century translator, “firmness, commodity, and delight” remain the essential components of all successful architectural design.”
University of Chicago Library
After the initial construction phase of excavation and installation of foundations, the building is what we refer to as “out of the ground”. The main challenges of cold-weather conditions early in the construction process center around the ability to adequately excavate, and keeping the exposed conditions suitable to receive the new work. As long as the ground is not so frozen that excavation is impossible, most work can proceed regardless of the temperature (excessive rain or snow may well be another matter).
The next hurdle is to make sure the excavated areas do not freeze, and are adequately protected while the work is formed, and constructed. New foundation work must be installed on stable, undisturbed, structurally adequate substrate. If the excavated area is allowed to freeze, the potential for differential movement is introduced, and any construction placed on top of these unsuitable soils will have a greatly increased potential for failure. The component parts of the soil play an important part in how it will react to extremes in temperature. Clay soils retain a great deal of moisture and can expand greatly under extreme cold. This can result in differential movement particularly if parts of the work are on different types of earth.
This past winter has revealed an issue with differing types of soil that is not entirely common. We have been contacted to review some parking lot issues, where extensive settling or sinking has taken place. A close review of this revealed that the areas of “sinking” are where excavation took place for electrical conduits. These trenches were filled with a gravel mix and properly compacted, however, as the adjacent soil is high in clay, it reacted differently than the gravel based trenches and resulted in the “settling” issues. This problem was not noticed for several years after paving was done, but our very cold temperatures, combined with a minimal snow pack, resulted in deeper penetration of the cold than usual leading to the issues mentioned above.
After the envelope is enclosed, the issues of cold-weather conditions are minimized, but not completely eliminated. It is important that the building be heated as construction continues. Many finishes have specific requirements both for heat and humidity. The issue often is that permanent heat is not always available, and temporary heating is employed. A significant problem, particularly with propane heating is that the interior environment becomes extremely moist (humid) which can have a deleterious effect once the permanent system is installed, and the building acclimates.
The exterior of the building is also of concern, as many different (particularly modern) types of sheathing and siding have significant thermal expansion rates. Particular care must be taken to ensure that thermal expansion is accommodated. While the material may look wonderful when first installed, if these issues are not addressed a variety of issues, from distortion (oil canning) up to buckling can occur. Many modern materials include specific scales for installation at various ambient temperatures.
Preparing for and adjusting to cold weather conditions is a vitally important task for designers and builders. The above information is by no means comprehensive, but rather offered as food for thought. Central New York winters can be tenacious, but they can also be manageable.