The frost line is the depth at which ice penetrates the ground and is important for building codes. It is determined by temperature, moisture level, and other factors. Local frost line maps and building inspectors are the most accurate sources. The depth varies greatly by location and structures must be installed below the line to avoid damage. Building codes often require compliance with frost line regulations.
The frost line is the depth at which ice, or frost, penetrates the ground. While the factor is often an afterthought in terms of general weather information, it is very important to building codes. The depth of frost is determined by a variety of factors including temperature, the length of time the air temperature stays below freezing, and the moisture level in the soil. Other factors, such as exposure, amount of vegetation and land use, may also play a minor role in determining the exact depth.
The easiest way to determine frost depth for an area is to consult a frost line map. The map serves as a general reference and finding a specific area should give you an accurate idea of what to expect even in the worst of winters. In most cases, local building inspectors should also have frost line information. This local source of information is often the most accurate because it is tuned to a specific area in a way that no national map can be.
The frost line can vary greatly from location to location. For example, in the United States, there is no frost line set for Florida, but it can be as deep as 60 inches (152.4 cm) in some northern sections of the lower 48 states. In Minnesota, the maximum is 60 inches (152.4 cm) in northern counties, but in southern counties, frost depths only reach 40 inches (101.6 cm). Some frost maps will show an average frost depth for the state, but this is very unreliable information and should not be the basis for any decisions due to the variance just described.
While the extent of frost penetration is not relevant to most people, it does matter because posts and building foundations must be installed in the ground below the frost line. If the buried portions of the supporting structure are above this line, the pressure exerted on the post or plinth will be upwards. This could push the post or footing out of the ground or even be responsible for major structural damage in buildings. Making sure these structures are placed at least several inches below the line alleviates this concern.
In fact, the placement of footings and posts is of such primary importance that it is often written into local building codes. Those who do not follow frost line building codes in an area may find that they have to make extensive design changes before it is approved for use. While this can be an inconvenience, it saves the consumer the trouble of having to make repairs to a job that was done wrong in the first place.
Protect your devices with Threat Protection by NordVPN
