Permafrost areas have very cold air temperatures, thin topsoil, and most water is frozen during the winter. Tundra is found at high latitudes and at high altitudes, where the permafrost has a very thin active layer. The active layer of tundra is too thin for trees to grow, because it cannot support a tree’s roots.

Permafrost is made of a combination of soil, rocks and sand that are held together by ice. The soil and ice in permafrost stay frozen all year long. A layer of soil on top of permafrost does not stay frozen all year. This layer, called the active layer, thaws during the warm summer months and freezes again in the fall.

When the earth remains frozen for at least two consecutive years, it’s called permafrost. If the ground freezes and thaws every year, it’s considered “seasonally frozen.”

The Reference Soil Group of the Cryosols comprises mineral soils formed in a permafrost environment. In these soils, water occurs primarily in the form of ice and `cryogenic processes’ are the dominant soil-forming processes. Cryosols are widely known as `Permafrost soils’.

Permafrost is ground (soil or rock and included ice and organic material) that remains at or below 0 °C for at least two consecutive years. Permafrost terrain consists of an “active layer” at the surface that freezes and thaws each year, underlain by perennially frozen ground.

Permafrost exists where the ground stays at or below 0° Celsius (32° Fahrenheit) for at least two years in a row. 24 percent of the land in the Northern Hemisphere has permafrost underneath it (Figure 1). So, permafrost makes up 23 million square kilometers (9 million square miles).

Montana (61 inches) New Hampshire (60 inches) Vermont (60 inches) Iowa (58 inches)

around 5 to 6 feet

While studying alpine soils in the Beartooth Mountains of Montana, Johnson and Billings (1962) found frozen ground, in late summer and in fall of different years, at depths of about a meter, and described it as permafrost. After 1965, reports of alpine permafrost were more frequent.

In many places in Canada, the general ‘rule of thumb’ when it comes to frost lines is 6 feet. However, Manitoba tends to buck the trend. In fact, in the Winnipeg area some engineers will tell you the frost line can extend as deep as 8 feet.

When building a fence make sure: The posts are set deep enough to go below the frost line – 36 inches is the minimum depth, 48 inches is better. The posts are plumb. The top of the fence is level and the fence is in a straight line. The wood is solid and clean, not full of cracks and knots.

5-6 feet

Dig post holes and install your fence posts. In Alberta’s climate, you’ll have to dig deeper than the frost line which is 3 feet deep, but some juristictions might require you to dig deeper than that. Save yourself the back-breaking work and rent a power auger to dig your post holes.

60”

Clay soil isn’t the ideal soil type for construction, but it doesn’t mean that you can’t build on it. Although the process will be more complicated than building on bedrock or loam, it’s still possible to use clay soil for construction.

Footings typically must extend below the frost line to prevent shifting during freeze-thaw cycles. Dig footing holes about 6 inches deeper than required. Fill the bottom of the hole with 6 inches of gravel and compact the gravel with a 2×4 or wood post.

5.5 feet

Dig post hole so diameter of the hole is 3 times the width of the post (i.e., the hole for a 4” wood post should be about 12 inches wide). The depth of the hole should be 1/3-1/2 the post height above ground (i.e., a 6-foot tall fence would require a hole depth of at least 2 feet).

4 feet

de-nagorg said: Just a suggestion: Dig your hole down to solid bedrock, then drill three 3/4 inch holes 6 inches deep into the bedrock, 120 degrees apart within the 12 inch diameter of the tube.

For an attached 12 x 12′ deck, you’ll need at least 3 footings, plus at least 2 more if you’re planning on building stairs with it. If your deck will be a different size, it’s easy to figure out how many you’ll need.

It’s right for a 4×4 fence post to have 1 bag per hole. The depth of the post hole should be half of the post height. For a 6′ above ground post, place 3 feet in the ground and use a post with an overall height of 9 feet.

To support a beam for a residential deck, does a Sonotube pier need any rebar? A. We usually recommend that a minimum of two pieces of #4 rebar be placed vertically in an 8-inch-diameter concrete pier supporting a structure. A larger-diameter pier should have four or more pieces of vertical rebar.

12”

Set footers a minimum of 6” below the frost line for your area to prevent movement during freezing temperatures. Pour about 6 inches of all-purpose gravel into postholes and pack the gravel tight by using the end of a wooden post.