Q: What is a frost line and do I need really need to build my BrickWood Box base slab so it touches the frost line since it sits above ground – not below. Also, I live in Michigan and we have long, cold, miserable, ugly winters – what’s the worst that would happen if we DIDN’T build to the frost line? Final question – what is my frost line depth?
A: The frost line is the depth of frost penetration in soil and/or the depth at which the earth will freeze and swell. Over a period of time, this freeze / thaw / freeze / thaw could possibly cause a minute shift to your BrickWood Box and that’s the worst that could happen. It will not flip or fall over and it will not look like the Leaning Tower of Pizza (you can cook a mean pizza in your BrickWood Box). If a shift or tilt does occur, it is easily fixable by digging under the corner that is tilting, lifting the BrickWood Box to your desired height, then filling the hole you just dug with a bag of concrete mix.
The depth of your frost line varies in different parts of the country so you will need to consult with a local structural engineer or see if you can find your city’s frost line requirements on the Google Machine. You may live in a city, town, village, county or state that REQUIRES all structures be built to the frost line.
It is your responsibility to find out this information prior to constructing your BrickWood Box.
If you choose to build your BrickWood Box base to your regional frost line, the diagram below shows you how to easily adjust your base slab. The following materials ARE NOT ON THE MATERIALS LIST – you will need to calculate and purchase these items separately. For EASY math calculations, jump on WolframAlpha.com. It’s like Google for math!