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Can the weight of a huge snow bank in a parking lot cause the foundation of a 2 story building to crack?

It is about 5 feet from the building and is approximately 40 feet long by 20 feet wide by 20 feet high.

When you have extra loading on the finished grade near a foundation it is usually called surcharge load. Although the foundation wasn't likely designed with a snow surcharge load of this size, it was likely designed to handle cars parking there instead. It would require a closer analysis to see which weighed more between the snow and the cars... possibly the snow.

The typical design snow density in Colorado is close to 18 lbs/cubic foot. Older snow, assuming this snow bank was created from clearing the parking lot, may be significantly heavier. Let's assume 30 lbs./cubic foot x 20' deep = 600 psf. That could be a pretty significant load at its maximum depth. The good news is that the snow bank is about 5 feet from the building. The farther from the building, the less load will contribute to laterally loading the foundation wall.

The surcharge load will put a lateral (sideways) pressure on the foundation wall. This will be more significant (concerning) if there is a tall basement below the building. If there is no basement or crawl space below grade, then I think you have very little to be concerned about with regard to the weight of the snow.

On the other hand, if the foundation is built on a clay soil that is subject to swell when wet, the melt-off water could effect (maybe crack or maybe just lift) the foundation unless a foundation drainage system was properly installed.

So a better answer depends on type of soil, type of foundation, if there is a basement or not, how much soil pressure was the original design intended to handle, etc. If you need a more accurate answer feel free to email me directly with more information on the situation.

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