Out in the Cold: Constructing buildings for Arctic conditions.

• Author: Kvapil, Rachael
• Position: CONSTRUCTION

The same advice for dressing in cold climates applies to structures as well: layering. Contractors apply control layers to the building envelope--the shell of a building that protects occupants from the elements--to manage the water, air, vapor, and temperature within a structure. This complex layering system within the foundation, roof, walls, windows, and doors that make up the building envelope isn't obvious to the untrained eye. However, professional testing will quickly reveal the effectiveness of the control layers that make up the building envelope.

A structure with effective control layers is both durable and comfortable. In general, it has a water-resistive barrier outside of the framing to keep water from getting into the walls, is airtight for energy efficiency, prevents condensation in the walls, and has the right type of insulated walls. Creating this kind of balance in a cold-climate building wasn't always the priority of contractors in Alaska. Dave Harrell, owner of Northern Home Consulting and former owner of Cold Climate Construction, says there was a big push in the '80s and '90s to make buildings airtight in the name of energy efficiency. However, it wasn't long before buildings started having problems with decay, mold, radon, and other issues. Harrell says contractors quickly found that sucking out the wet, stale air with an exhaust fan often led to backdrafting, pulling carbon monoxide from heating appliances into the living space and making people sick.

"We learned that the best practice is to have sealed combustion heating appliances and adequate balanced ventilation, such as with a heat recovery ventilation system," says Harrell. "Builders adopted the adage 'build it tight and vent it right.'"

Harrell considers moisture management to be one of the biggest challenges of designing and constructing cold-climate structures. He says moisture management is more than just the precipitation on the exterior of the building and the vapor from underneath but also the management of the moisture produced by those inhabiting the building doing daily activities such as cooking, washing, and simply breathing. Properly ventilating a building requires contractors to consider theentire design and specifications--and to be willing to ask for help when they don't know the answer.

The Right Stuff

Of all the materials in the control layers, insulation often gets the most attention. Over the years, manufacturers have developed a range of...