Roof Snow Drift

Combination of over the ridge drift loads with roof step drift distribution of drift loads when the space available for drift formation varies in the direction perpendicular to the upwind fetch slope of the top surface of snow drift on a gable roof as a function of roof slope use this new drift load guidance as the basis for a.

Roof snow drift.

Version 0 0 2 september 14 2020. Version 0 0 2 september 14 2020. Density snow density γ. The snow turbulence eventually results in the upper.

The existing building has a flat roof. After you obtain the roof slope factor from those sections in asce 7 10 the. Rain load s r. The addition is a lower roof which is sloped shed roof.

Roof slope factor for multiple folded plate sawtooth and barrel vault roofs. We re designing an addition to an existing building. Ground snow load s s. Density snow density γ.

Snow drift loading lower adjacent roofs. Windward drift results from snow blown against a projection or wall below a high roof. A walk through and example of calculating snow drift loads and how to apply them roof designs usually present multitudes of roof elevations and rarely offer one single roof height. Because of this there are roof areas higher and lower than each other and are subject to snow drifts.

Typically the windward drift height hdw is less than the leeward drift height hdl unless the length of the lower roof is considerably longer than the length of the upper roof. The amount of additional snow load or surcharge. For leeward snow the snow doesn t blow sideways across the high roof and drop vertically down to the low roof. Even with a 20 ft parapet snow will drift onto the lower roof.

If your structure has a sloped or flat roof you still need to calculate the flat roof snow load. Rain load s r. Kn m 3 if nothing input γ will calc as per cl. Importance factor i s.

Ground snow load s s. Snow capture wall roof step drift ratios variable dr generally decreasing functions of pg lu 67 snow capture wall want wall big enough to capture all expected snow transport factor of 2since dr based on capture of half expected snow transport trapping efficiency 50 aw γ 2 dr pg lu aw αho2 ho 2 dr pg lu αγ 68. Snow drift on sloped roof vmirat structural op 18 aug 09 11 36. Flat roof snow load p f this is the snow load calculated in the previous section.

Snow drift loading lower adjacent roofs. The lower roof slope is 4 in 12.