Designs That Work
Very Cold Climate
Introduction - Building for a Very Cold Climate
A Very Cold climate is defined as a region with approximately 9,000
heating degree days or greater and less than approximately 12,600 heating
degree days. In North America, very cold climate regions vary in annual
precipitation from less than 20 inches to more than 60 inches.
Condensation of warm moist air on cold surfaces within the building
assembly during winter months is a concern in design and construction. In
addition, in many areas ground water presents a concern because the
majority of houses are built with basements or crawlspaces. Rain, snow and
ice damming represent threats to the integrity of the building enclosure.
Until relatively recently, the focus in terms of moisture control in
very cold climates was moisture drive from the interior during the heating
season. The widespread introduction of centralized cooling in very cold
climates, however, can produce cold interior surfaces on which warm moist
air infiltrating from the exterior can condense during the summer. If
interior vapor barriers are installed in conjunction with air conditioning
serious moisture problems can occur. Interior vapor barriers should be
avoided in this climate region. Controlling moisture and air flow in the
building enclosure in this climate is critical to designing and building a
durable, comfortable home.
Note: Don’t forget that it is always the conditions that you
actually experience in your area that determine the appropriate building
design and construction details. The Building America Climate Zones
provide simplified groupings of geographic locations that may actually
vary greatly in terms of weather, and therefore should be viewed as
guidelines.
Map 1: Annual Precipitation – North America
Map 2: The Building America Hygro-Thermal Regions
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