How to calculate carport roof loads

Updated April 17, 2017

Roof loads are used to determine the size of beams, joists and columns that support a roof. Calculate the carport roof load using a combination of the dead-load and live-load measurements. The dead load consists of the actual weight of materials that comprise the roof, plus any fixed equipment that the roof supports. The live load is determined by applicable building codes and usually consists of components for snow load, and the estimated weight of persons and equipment required to maintain the roof. Both dead load and live load are expressed in pounds per square foot.

Measure the length and width of the carport to determine the area of the roof in square feet. Multiply the length by the width to get the measurement for the area.

Determine dead load by identifying the amount of each construction material used in the roof. Identify the weight of each, using the American Society of Civil Engineers Publication 7-05 as a the nationally accepted source for weights of construction materials. Add the weight of equipment, if any, mounted on the roof. Divide the total roof weight by the area of the carport to express dead load in pounds per square foot.

Determine the live load. Consult the building code for your municipality or region for specific weights and requirements.

Add the dead load and the live load to obtain the total load, in pounds per square foot, of a carport roof.


Make a list containing each construction material and its weight, to stay organised.


Underestimating a carport roof load could lead to the roof's collapse. Double-check your work.

Things You'll Need

  • Tape measure
  • Calculator
  • Local building code
  • American Society of Civil Engineers Publication 7-05
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About the Author

Gregory Jenkins earned his B.S. in Architecture from the University of Cincinnati in 1971. Technical writing has been an integral part of his 30-year construction career. His interests have recently expanded to include architectural history, and preservation, and he is the author of a weekly blog featuring landmarks in Chicago and the the newly published book "Chicago Figural Sculpture, A Chronological History."