Snow Load On House Roof

Local building codes dictate the snow load required for residential roofs.

Snow load on house roof.

Pitched roof snow load. If you want to calculate these values by hand use the following formulas. Saturated snow weighs about 20 lbs cubic foot. 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.

Estimate the weight of snow on your roof. Snow loads are influenced by elevation general weather and moisture patterns slope direction exposure roof or trail bridge configuration and wind direction and severity. Some general guidelines that we try to adhere to. Flat roof snow load formula.

It extends outward in both. For any rafter the portion of the roof deck that transfers this load is the tributary area. You can also find the load per square meter or square foot of roofing by opening the advanced mode. Once you know these values our snow load calculator automatically finds the total weight of snow on your roof.

The roof should be designed with overhangs large enough to provide protection for the walls and windows below. 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. Avoid areas that will trap snow and lead to excessive accumulation especially on the north side of the roof. Snow load thickness density.

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. House roofs should support 20 lbs square foot of snow before they become stressed. If your roof is flat it is more likely to have snow load problems than if it is pitched. Roof slopes lower than 4 12.

Overestimation of snow loads can unnecessarily increase the cost of construction. Most roofs are designed to handle the snow load of a typical winter. As a homeowner living in an area with white winters you need to know how much snowfall. Wet snow can be nearly three times heavier than dry fluffy snow.

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. 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. Don t be too hasty to shovel the snow off your roof says a north dakota state university agricultural engineer.