Snow Load On House Roof

Wet snows can weigh four times as much as dry snows causing a considerable amount of weight baring down upon every square foot of greenhouse roof surface.

Snow load on house roof.

House roofs should support 20 lbs square foot of snow before they become stressed. It extends outward in both. Snow load thickness density. Pitched roof snow load.

Snow loads are influenced by elevation general weather and moisture patterns slope direction exposure roof or trail bridge configuration and wind direction and severity. So while a cubic foot of fresh powder might weigh in at 7 pounds that same amount of wet packed snow could be more like 20. Most roofs are designed to handle the snow load of a typical winter. How to calculate roof snow loads roof snow load calculations.

Flat roof snow load formula. The roof deck collects the snow load and transfers the weight to the rafters. Snow can either blown from the low side of the roof towards the high side or is blown off the higher area of the roof onto the lower projected side. If your roof is flat it is more likely to have snow load problems than if it is pitched.

As a homeowner living in an area with white winters you need to know how much snowfall. For any rafter the portion of the roof deck that transfers this load is the tributary area. If you want to calculate these values by hand use the following formulas. Once you know these values our snow load calculator automatically finds the total weight of snow on your roof.

Snow load of a greenhouse is based on expected ground accumulation greenhouse roof slope whether the structure is a gutter connect or free standing greenhouse and if the greenhouse is heated or unheated during the time of snowfall. You can also find the load per square meter or square foot of roofing by opening the advanced mode. Saturated snow weighs about 20 lbs cubic foot. The amount of additional snow load or surcharge depends on the difference in height of the two adjacent roofs and the lengths of roof perpendicular to the drop in height.

Contact your local building code department to determine the snow load requirements for your area. Estimate the weight of snow on your roof. Don t be too hasty to shovel the snow off your roof says a north dakota state university agricultural engineer. Just because one roof has gone down doesn t mean every roof in the area is in danger says ken hellevang of the ndsu extension service.

The roof should be designed with overhangs large enough to provide protection for the walls and windows below. Overestimation of snow loads can unnecessarily increase the cost of construction. Local building codes dictate the snow load required for residential roofs. Roof slopes lower than 4 12.