# How to calculate roof snow loads

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Most of the UK doesn't often experience heavy snowfall but engineers still need to factor into this calculations when designing buildings. To work out whether roofing materials are up to the weight -- kg/m2 or kilogram per square metre (psf or pounds per square foot) -- of snowfall. This pressure increases or decreases based on the pitch of the roof. You can compute real-time snow load for quick decision-making or use official figures to design a new building.

Push the ruler into the snow horizontally in a spot that is representative of the overall snow depth and record the depth in centimetres or inches.

Convert your depth measurement to a figure expressed in metres or feet. For instance, using a snow depth of 38 cm (15 inches): 38 cm divided by 1,000 yields 0.38 m (15 divided by 12 inches yields 1.25 feet).

Collect 0.028 cubic metres (1 cubic foot) of the snow on the ground, choosing a sample that is representative of the overall snow pack, and weigh it. This quantity of snow may weigh up to 91 kg (20 lb) depending on how fluffy or dense it is.

Multiply the depth of snow by the weight. For example, 4 kg per cubic metre x 0.38 m = 1.52 so the amount of pressure the snow is exerting on the ground is 1.52 kg per square metre (11.25 lbs per square foot).

Estimate the total weight of snow in your garden by multiplying the size of the area in square metres by the snow load. For example, using a 25 by 20 metre garden: 500 times 1.25 yields 625 kg (1,378 lb) of snow. Use this same calculation to find the total weight of snow on a flat roof.