Roof Weight Distribution

The load increases with the use of heavier roofing material.

Roof weight distribution.

Load distribution on a roof. For example the weight per square footing for asphalt shingle weight per 100sq ft lbs range is 190 250. The straight lengths of wood known as members that roof trusses built with are connected with intersections that distribute the weight evenly down the length of each member. Actually with snow you don t get more load along the slope of the rafter.

The weight per 100sq ft kg range is 85 110. I need to be able to show this to get the inspector to buy in so i ll need formulas with the answer. I an installing a solar array on the roof 24 modules 13 78 sqft each. My racking system with the modules weigh about 42 lbs per module.

Roof trusses are created by attaching the ends of members to joints known as nodes. The live loads a truss is required to bear are determined by local building codes. If the bottom chord of a roof truss functions as a floor joist such as in an attic room it carries a live load that also varies by use but a typical live floor load for a residential space is about 40 pounds per square foot. Thus as the roof gets steeper the rafter gets longer and the weight of roofing materials increases.

This is all of the natural stresses imposed upon a roof such as snow loads rain loads and wind loads. This is because as snow falls vertically it spreads itself further along a sloping rafter and so. A roof is composed mainly of two parts the cladding or external material and the internal support structure which holds it up. You get the same load as a flat roof with the same run would get.

Structural engineers use the solar panel roof load calculator to come up with the correct load capacity of the roof material. This is highly regional as weights of snow for example range from 10 to 300 pounds per square foot based on moisture and volume of the snow. Metal roofing aluminum or steel panel sheet or shingle 1 2 lb m ft 2 5 9 kg m 2 terne plate copper bearing steel sheet 0 7 lb m ft 2 3 4 kg m 2 wood shingle or shake 2 4 lb m ft 2 11 7 kg m 2. Dead load weight of roof trusses top chord bottom chord webs weight per lineal foot plf 2x4 2x4 2x4 4 3 2x4 2x8 2x4 5 6 2x6 2x4 2x4 4 8 2x6 2x6 2x4 5 5 2x6 2x6 2x6 6 2 2x6 2x8 2x4 5 9 2x6 2x10 2x4 6 6 2x6 2x10 2x6 7 2 2x8 2x8 2x4 6 6 2x8 2x8 2x6 7 2 2x8 2x10 2x8 8 4 dead load weight of floor trusses depth in inches top chord bottom chord.

Determine the transient load of the roof. A roof truss is a triangular wood structure that is engineered to hold up much of the weight of the rest of the roof. A majority of roofs can withstand the weight of solar panels. The local ahj has ammended snow loads for the area to 40 psf.

The amount of weight the internal support structure can carry without the roof collapsing can be described as its load bearing capacity.