Tag Archives: frost heaves

How to Re-level a Garage

Auntie Em, Auntie Em My Garage Has Lifted 

Well, it wasn’t from a twister and this article has nothing actually to do with Auntie Em or actress Clara Blandick who played Auntie Em in 1939’s film classic The Wizard of Oz. For trivia buffs, Blandick also played a part in 1937’s original A Star Is Born.

Reader GEORGE in LAGRANGE might be wishing a twister had hit his garage, so insurance would pay for a replacement. George writes:

“Due to the freezing and thawing cycle my pole garage has lifted about 7 inches since it was built 12 years ago. You can now see the outside grass from inside the garage. And it has not lifted evenly so the garage is unlevel.”

George’s post frame garage has some challenges, none of them ones with an easy fix. How did his garage get this way? There are three possible major contributors to this garage’s current situation. These would include:

Inadequate site preparation

At a minimum, site preparation includes:
· Remove all sod and vegetation.
· For ideal site preparation, remove topsoil and stockpile for later use in finish grading. In frost prone areas, remove any clays or silty soil
from within future building “footprint”.
· Replace subsoil removed from around building with granulated fill to help drain subsurface water from building.
· Distribute all fill, large debris free (no pit run), uniformly around site in layers no deeper than six inches.
· Compact each layer to a minimum 90% of a Modified Proctor Density before next layer is added. Usually, adequate compaction takes more than driving over fill with a dump truck, or
earth moving equipment.

For more details on proper site preparation please read: https://www.hansenpolebuildings.com/2011/11/site-preparation/

Column Depth

Bottom of column encasement needs to be below frost line. This is a no-brainer.


Read more about what causes frost heaving here: http://www.hansenpolebuildings.com/2011/10/pole-building-structure-what-causes-frost-heaves/.

There is going to be no easy or inexpensive fix to George’s situation. An investment into a geotechnical engineer who could provide a thorough site evaluation along with solutions might be money well spent.

Building could be brought back to level by excavating at each raised column to well below frost depth. Cut off columns at base of splash plank (while supporting building from falling), then remove embedded portion of column. Place an appropriately sized sonotube in excavation with top of tube at grade. Pour premix concrete into tube and place a wet set Sturdi Wall bracket – expertly placed to receive upper portion of column. https://www.hansenpolebuildings.com/2013/11/sonotube/

If all of this sounds daunting (it would be to me), a consideration could be demolition and start over from scratch.

Pole Building Structures: What Causes Frost Heaves?

I always give credit “where credit is due” and my next subject is supported by the online writings of a Professional Engineer, Mr. Harris Hyman.  He wrote about frost as far back as July 1994 in Practical Engineering,  Like Mr. Hyman, I too like to dig down deep into why some problem is caused, before I figure out the solution. Today and far into the future, frost heaves are just one of those things we need to be aware of, and plan buildings, (pole buildings or otherwise) accordingly.

This is what Mr. Harris Hyman, P.E. had to say:

As an engineer, I want to understand a little about the problem before I recommend corrective measures. Research work on frost heaving is somewhat limited, but there is a theory. Around the end of winter in cold regions, the earth develops a characteristic temperature profile: At the surface, the earth takes on the day’s temperature. But a couple of inches below, the ground temperature cools to approximately the February average temperature of the region. As we go deeper into the earth, the temperature rises, until several feet deep it reaches the annual mean temperature of the area.

 The soil usually reaches its coldest temperature in March, when the freezing point reaches down to the region’s frost line. Below this depth, the soil and groundwater almost never freeze. But at the frost line — the 32°F point — the groundwater freezes, forming a thin sheet of ice. In soils that are porous enough to allow moisture to move, more groundwater touches this ice. The groundwater accumulates, freezes, and builds up into a bulge called an ice lens, which might be anywhere from several inches to a few feet across. The bulging ice lens pushes the earth above up into a frost heave. Aggravating the effect is surface melting, which also occurs at the end of March. The snow melt water moves through the ground, touches the ice lens, and adds to the bulge.

 This is why, every spring, rural roads up North develop sinuous dips and dives. The ice lenses form during the winter, pushing up spots on the asphalt surface. When the weather warms sufficiently to melt the ice lenses, the unsupported asphalt sags and leaves low spots and potholes. On major highways, which cost a lot more to build, the base layer is sufficiently permeable to carry away groundwater, so heaves are rare.

Let’s take a break here, reflect on this a bit and what it might mean to  pole buildings – the ice lens pushing up on asphalt concept – means it can also push up on buildings at the frost line.  Come back tomorrow to hear more of what Mr. Hyman may have to say on the subject of frost heaves.