Roof Weight Rating

The dead load of a typical asphalt shingled wood framed roof is about 15 pounds per square foot.

Roof weight rating.

Though in many cases the racks can withstand greater loads to avoid damage to your vehicle it is important to understand your vehicles limitations. There are 3 types of load rating and the cargo rating. This is all of the natural stresses imposed upon a roof such as snow loads rain loads and wind loads. When it comes to estimating the weight of an existing roof field verification of the in place construction is necessary.

Driving either on highways or around town will be fine with this type of dynamic load. The load increases with the use of heavier roofing material. Asphalt shingle or asphalt fiberglass composite shingle 2 7 lbm ft2 13 2 kg m2 metal roofing aluminum or steel panel sheet or shingle 1 2 lbm ft2 5 9 kg m2 terne plate copper bearing steel sheet 0 7 lbm ft2 3 4 kg m2 wood shingle or shake 2 4 lbm ft2 11 7 kg m2 zinc roofing 1 6 lbm ft2 7 8 kg m2. A built up roof for example will typically include the built up membrane itself with or without gravel as well as some kind of insulation and cover board which will vary in thickness from roof to roof.

When you have the roof racks to support your rooftop tent fitted they will be placed around 30 inches apart. 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. Wind loads depend on wind speed and can vary as widely as the snow. Check the racks have a weight rating of 125 lbs or more as their dynamic load which will then be at least be equal to or greater than the weight of the rooftop tent.