Building on Permafrost: Changing climate is just another challenge for builders keeping it cool in the Arctic.

• Author: Simonelli, Isaac Stone
• Position: Building Alaska

When constructing in the Arctic or near-Arctic regions of the world where permafrost dominates, the adage "If it's frozen, keep it frozen; if it's thawed keep it thawed" provides a strong foundation. Doing this, however, is one of the greatest challenges for engineers and construction companies that specialize in building in some of the coldest places on Earth.

Frozen Foundations

"The design of the foundation, which is the interface between permafrost and the building, can be directly related to the success of or failure of a building on frozen ground," explains Bruno C. Grunau, chief programs officer at the Cold Climate Housing Research Center (CCHRC). CCHRC is an industry-based, private, nonprofit corporation with the mission to promote and advance the development of healthy, durable, and sustainable shelter for Alaskans and other circumpolar people. "Once the permafrost thaws, the foundation can sink, damaging the building it supports. The key to successfully building on frozen ground in the North is to maintain a near-constant subsurface thermal regime where the foundation bears on the soil."

A poorly designed or poorly maintained heated structure can be the catalyst for repeated thawing and freezing cycles of the ground, causing it to heave, slough, and even creep--usually to the detriment of the building.

"There are a myriad of things to consider when looking at a project on permafrost. I always first consider the importance of the project and the consequences of a failure," Arctic Foundations President Ed Yarmak says. "And then, of course, there's the budget, which turns into the usual constraint for many public projects. Budget and service life are the main drivers. Sometimes there's trade-offs... and service life is compromised."

An early step in the design process of a project is to get good site data. Ideally, a team would be able to obtain the vertical temperature distribution down into the permafrost over the course of a year.

"We hardly ever get that data because of schedules or budgets," Yarmak says. "Engineers can make estimates, but then, that's just another uncertainty in the design that needs to be taken into account."

What data they are able to collect allows a team to--among other things--determine if the site is thaw stable, which is generally a factor of how much ice is in the permafrost material.

"If it is thaw stable, then standard construction techniques utilized for non-permafrost sites in cold regions can generally be used," Yarmak says. "If it is not thaw stable, then engineers either design the structure using specialized materials and construction techniques to keep the heat balance negative or build the structure in a way that it can be maintained as the permafrost thaws and settles."

Permafrost Permutations

Though many think of permafrost as permanently frozen soil, it can bo more broadly defined as any earth materials (granite bedrock in the mountains to silty soil on the Tundra) that remain below 32 degrees Fahrenheit for at least two consecutive years.

These back-to-back years of freezing temperatures are caused by a negative heat balance, meaning that more heat leaves the ground during the winter than is...