Roof Snow Load Calculator
How Does It Work?
The purpose of the calculator is to help you determine the amount of snow load that a sloped roof can safely support. The snow load refers to the weight of the snow that accumulates on the roof, and it can be quite significant in areas with heavy snowfall.
The calculator takes several inputs, including the area of the roof, the slope of the roof, and the thickness and density of the snow. The area of the roof is simply the total area of the sloped surface that would be covered by snow. The slope of the roof is specified using a standard rise-over-run ratio, which is the vertical height of the roof (rise) divided by the horizontal distance (run).
Once these inputs are provided, the calculator uses a formula to calculate the weight of the snow load that the roof bears. This formula takes into account the area of the roof, the slope of the roof, the thickness of the snow, and the density of the snow. The weight of the snow load is expressed in pounds.
Maximum allowed snow weight per square foot
This table shows the maximum snow load allowed for different states in the US, based on the ASCE 7-10 standard. The values shown in the table are in pounds per square foot (psf).
| State | Maximum Snow Load (psf) |
|---|---|
| Alabama | 20 |
| Alaska | 300 |
| Arizona | 20 |
| Arkansas | 20 |
| California | 30-50 |
| Colorado | 30-70 |
| Connecticut | 30-70 |
| Delaware | 30-40 |
| Florida | 10-20 |
| Georgia | 20-30 |
| Hawaii | 0-10 |
| Idaho | 30-100 |
| Illinois | 20-40 |
| Indiana | 20-30 |
| Iowa | 20-60 |
| Kansas | 20-40 |
| Kentucky | 20-30 |
| Louisiana | 20 |
| Maine | 40-90 |
| Maryland | 30-50 |
| Massachusetts | 30-70 |
| Michigan | 30-70 |
| Minnesota | 30-70 |
| Mississippi | 10 |
| Missouri | 20-40 |
| Montana | 40-130 |
| Nebraska | |
| Nevada | 20-50 |
| New Hampshire | 40-90 |
| New Jersey | 30-50 |
| New Mexico | 20-30 |
| New York | 30-70 |
| North Carolina | 20-30 |
| North Dakota | 20-50 |
| Ohio | 20-40 |
| Oklahoma | 20-30 |
| Oregon | 20-60 |
| Pennsylvania | 30-70 |
| Rhode Island | 30-50 |
| South Carolina | 20-30 |
| South Dakota | 20-50 |
| Tennessee | 20-30 |
| Texas | 20-30 |
| Utah | 30-70 |
| Vermont | 40-90 |
| Virginia | 20-40 |
| Washington | 20-200 |
| West Virginia | 30-60 |
| Wisconsin | 30-70 |
| Wyoming | 30-90 |
Why are the values so different?
The variation in snow load limits between different states and regions is due to a number of factors, including topography, climate, and local building codes and regulations.
E.g. in the case of Washington state, the range of snow load limits is quite large (20-200 psf) due to the state's diverse topography and climate. In general, areas with higher elevations and more mountainous terrain tend to have higher snow loads, as the snow tends to accumulate and remain on the ground for longer periods of time. In addition, areas with more severe winter weather conditions, such as heavy snowfall and high winds, may require higher snow load limits to account for the added weight and stress on roofs.
In contrast, Mississippi has a lower snow load limit of 10 psf due to its relatively mild climate and low frequency of snowfall. The state's building codes and regulations are designed to ensure that roofs are able to withstand typical weather conditions, including rain, wind, and occasional snowfall, but do not need to account for heavy snow loads.
It is worth noting that the snow load limits listed in the table are intended as general guidelines, and that specific requirements for a given project may vary based on a number of factors, including the specific location within a state, the design of the building, and the intended use of the structure. It is always important to consult with local building codes and regulations, as well as qualified professionals such as structural engineers, to ensure that the roof is designed and constructed to withstand the appropriate snow load for the specific conditions of the project.
What is the ASCE 7-10 standard
The ASCE 7-10 standard is a set of guidelines and specifications for the design of buildings and other structures in the United States. Specifically, it provides information on the loads and forces that a building may be subjected to, including snow, wind, seismic activity, and other environmental factors.
The ASCE 7-10 standard is used by engineers, architects, and other building professionals to ensure that the structures they design are safe, durable, and able to withstand the forces that may act upon them over the course of their lifespan.
The snow load limits that I provided earlier are based on the ASCE 7-10 standard, which provides specific requirements for the design of roofs and other structural elements to account for the weight of snow and other environmental factors.
The standard is updated periodically to reflect new information, changes in building codes and regulations, and advances in engineering and construction technology. The most recent version is ASCE 7-16, which was published in 2017.
In general, the ASCE 7-10 standard is designed to ensure that buildings are able to withstand a wide range of environmental factors and forces, and that they are built to last for many years without significant damage or failure.
What is the ground snow load?
The ground snow load is a measure of the weight of snow that accumulates on the ground during a winter season. Specifically, it refers to the weight of a standard depth of snow (usually 1 inch or 1 foot) that would be expected to accumulate over the course of a typical winter season in a given area.
Ground snow loads are an important factor in the design of buildings and other structures, as they help to determine the amount of snow load that the structure must be able to withstand. In areas with high snowfall, the ground snow load can be quite significant, and the design of the building must take into account the added weight and stress that the snow can place on the roof and other structural elements.
Ground snow loads are typically determined using historical weather data and other information about the climate and topography of the area. This information is used to calculate the expected amount of snow that would accumulate on the ground over the course of a typical winter season, and this value is then used to determine the design snow load that must be used for the building or structure.
The ground snow load is just one of several factors that are considered in the design of buildings and other structures, but it is an important one, as it helps to ensure that the structure is able to withstand the forces that may act upon it over the course of its lifespan.
