Roof Slope Factor For Snow Load

The boca code recognizes this and allows you to use the horizontal projection of the roof when calculating snow loads.

Roof slope factor for snow load.

Residential roof with asphalt wood shingles or shakes would use fig. To figure out the load on your roof take the depth of snow in feet and multiply it by the weight of a cubic foot of snow. P s sloped roof snow load in psf c s roof slope factor as determined by asce sec. P s c s p f the thermal factor c t from table e 3 determines if a roof is cold or warm slippery surface values shall be used only where the roof s surface is unobstructed and sufficient space is available below the eaves to accept all the sliding snow.

7 2b with a c s 1 0 p f flat roof snow load in psf. After you obtain the roof slope factor from those sections in asce 7 10 the balanced design snow load for the sloped roof can easily be calculated using equation 7 4 1. C s 1 uls. The sloped roof snow load p s shall be obtained by multiplying the flat roof snow load p f by the roof slope factor c s.

P s c s p f where. R802 10 2 and designed according to the minimum requirements of asce 7 10. Slope 30 degrees. Roof snow load nbc 2010 version 0 1 0 september 13 2020.

Calculate sloped roof snow load p s using the following equation. If your structure has a sloped or flat roof you still need to calculate the flat roof snow load. Snow load thickness density. If you want to calculate these values by hand use the following formulas.

For locations where 0 pg 20 psf all roofs with a slope w 50 with w in ft shall have a 5 psf rain on snow surcharge. The balanced snow load is applied everywhere where the roof structure is located. You can also find the load per square meter or square foot of roofing by opening the advanced mode. 7 4 1 7 4 4 and asce figure 7 2 below.

All of the load cases required to fully design an actual structure are not provided by this calculator. Once you know these values our snow load calculator automatically finds the total weight of snow on your roof. For dead loads you are correct. This is the snow load calculated in the previous section.

This rain on snow augmented design load applies only to the balanced load case and need not be used in combination with drift sliding unbalanced or partial loads. Boca also allows you to reduce the snow load for roofs with slopes greater than 30 degrees presumably because snow will slide or blow off steeply pitched roofs. For the design of an actual structure a registered and licensed professional should be consulted as per irc 2012 sec.