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How To Build On Permafrost

How To Build On Permafrost

And have your house remain where it is
By Tim Edwards
Feb 18
2016
From the February 2016 Issue

A level house doesn’t have to be a luxury. Some older Northern homes and shacks have floors that rise and slide at odd places, making walking across them a risky prospect until you get used to the topography.

This is because of permafrost. While the top layer of the ground freezes and thaws with the seasons, deeper down are layers of earth that the summer sun’s warmth doesn’t reach, and which stay frozen for multiple years. When more ground freezes, it expands, pushing the ground above it upwards (known as “frost-heave”). When permafrost thaws, the ground sinks (“thaw settlement”). But we’ve been building homes up here for long enough that we’ve figured a few things out. Here’s what you should know.

Bedrock: The simplest solution is building on bedrock, if you can.

Pilings: Stacks of wooden blocks underneath that can be adjusted if needed; or steel poles to hold up the house, which are drilled far enough down that the permafrost isn’t likely to thaw anytime soon. They also provide space between the house and ground, so the home’s heat doesn’t melt the earth.

Screwjacks: Basically, building the house on adjustable jacks (that are on wooden platforms with gravel underneath). You sometimes need to fine-tune them as the topography changes.

Thermosyphons: This newfangled technology consists of large cylinders, drilled deep down into the permafrost, which extract heat from the ground and release it into the atmosphere. They don’t require energy and have no moving parts; instead, they use a liquid-vapour system and heat transfers. These are being used more and more in construction in the North, and some folks have an amazing amount of faith in the technology. The federal government is relying on them to keep arsenic in Yellowknife’s Giant Mine frozen and out of the groundwater in perpetuity. But in 2013, when Iqaluit’s new RCMP detachment began to sink, the engineer behind it went to the press saying the two malfunctioning thermosyphons had been deliberately sabotaged. So if you plan on building with these puppies, but want to keep out enemies, maybe build a tall fence around them as well.