Quck answer
To calculate the load bearing capacity of a flat roof, you need to consider several factors. First, determine the maximum weight the roof can support per square foot. This is usually specified by the building code or the roof manufacturer. Next, calculate the total weight of the roof materials, including insulation, decking, and any additional layers. Add the weight of any equipment or structures on the roof, such as HVAC units or solar panels. Finally, consider the live load, which includes the weight of people, snow, and any temporary equipment. By adding all these weights together, you can determine the load bearing capacity of the flat roof.
For the average person, determining the load on a flat roof can be a difficult task that requires knowledge of building materials, their weights, and local building codes. In the United States, the ASCE 7-05 is the standard guide that provides weights and stresses for all building materials in pounds per square foot. It also includes load factors for natural stressors like wind, rain, and snow. However, it is important to consult your local building codes for verification of these values as they can vary significantly based on climate.
Step 1
To begin, calculate the dead load of the roof. This involves determining the combined weights of all the individual roof materials, as well as anything permanently attached to it. This includes the materials used for the ceiling under the roof and any HVAC components that are installed. The ASCE 7-05 provides these values in pounds per square foot.
Step 2
Next, calculate the live load of the roof. This involves adding the weights of any individuals who may be working on the roof, as well as the combined weight of all the tools and equipment used by those workers.
Step 3
Now, determine the transient load of the roof. This includes all of the natural stresses that the roof may experience, such as snow loads, rain loads, and wind loads. The weights of snow, for example, can range from 10 to 300 pounds per square foot depending on the moisture content and volume of the snow. Wind loads can vary greatly depending on the speed of the wind.
Step 4
Loads on flat roofs can vary significantly across different regions of the country.
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Finally, add up all three of these load values to calculate the total load on the flat roof.
