Most modern roofs are designed to support a certain amount of snow load. However, excessive snow can cause structural failures in many structures.
To determine if your structure can handle the expected snow load, you will need to perform a simple calculation. The first step is to gather information about your structure and its contents.
Roof Materials
Depending on the type of roof, different materials may be used. Each material has its strengths and weaknesses. The best roofing material depends on your specific needs, but all materials are designed to withstand a certain amount of snow.
Changes to the structure of a building can also affect the snow load. Adding or removing roof sections can cause the snow load to be unbalanced, putting more strain on some parts of the roof than others. It is widespread in buildings that combine old and new sections, such as farm machinery shops or storage structures.
Fortunately, figuring out the snow load on your roof is relatively simple. You need to know the roof pitch and properties, the ground snow load for your area, and a few other factors. You can find a roof snow load calculator online that will help you determine the proper snow load for your home or business.
Roof Pitch
The maximum allowable weight of snow for a roof depends on its location and how flat or sloped it is. A flat roof is more likely to have problems with snow loading than a pitched one because the wind tends to blow the snow off rather than accumulate it.
To determine the roof’s snow load, you must measure the thickness of the snow cover. It is easiest to push a yardstick into the snow on the roof and then express your result in feet (rather than inches).
Remember, the density of the snow directly affects its load-carrying capacity. The structure could be damaged if the snow exceeds your roof’s load-carrying capacity. That is why inspecting the building regularly and removing snow and ice is essential. It is also a good idea to plan how to manage the snow load during winter and be prepared for a sudden blizzard.
Roof Properties
Nothing is lighter than a snowflake, but the weight can become significant when you add thousands. That’s why roofs have to be able to carry a specific amount of weight before structural failure occurs.
State building codes establish a minimum design snow load for buildings and other structures based on historical weather data, including wind speed/direction and snowfall. But the actual snow load that a structure can withstand may be more significant if you consider other factors like:
Roof slope factor. Due to imbalanced snow loads, many structural collapses occur in farm machinery shops and similar buildings. These are caused by varying slopes of adjacent roof sections that cause snow to accumulate unevenly. Regular inspections should account for structural changes and include a review of the balanced snow load. It will help to minimize structural safety issues that may occur. Similarly, new additions to the roof should be designed and built with this in mind.
Ground Snow Load
The ground snow load is the total amount of snow accumulating on flat ground during a typical snowfall. It is typically measured at weather stations, correlated with snow depth data, and multiplied by various factors to obtain the roof snow load for codified structural design.
Several factors affect the ground snow load, including surface roughness and roof exposure. These factors can cause snow to drift from one side of the building to another, reducing the amount accumulating on the roof. They also affect the density of the snow, as drier snow is lighter and less dense than wet snow.
The final factor is the thermal condition of the structure, which includes air temperature and wind speed. For example, a warmer, less windy environment will result in a lower ground snow load because the snow will melt and blow off the structure more easily. It can reduce the overall snow load on the roof by a significant amount.
