Designs That Work
Mixed-Humid Climate
Introduction - Building for a Mixed-Humid Climate
A Mixed-Humid climate is considered a region that receives more than 20
inches of annual precipitation, has approximately 4,500 heating degree
days or fewer, and where the monthly average outdoor temperature drops
below 45°F during the winter months. This winter temperature limit
establishes a “northern” boundary for this climate region and provides the
rationale for differentiating regions where unvented roofs can be
constructed without controlling the temperature of the roof deck, using
insulation to address wintertime condensation.
This is a particularly challenging climate—we have significant heating,
significant cooling, high moisture levels most of the year, and many areas
of moderate to high rainfall. Controlling the infiltration of
moisture-laden air into the building envelope and keeping moisture away
from cold surfaces are major goals of design and construction. Ideally,
wall and roof assemblies are designed to promote drying to both the
interior and exterior in this climate.
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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