Building Loading - Snow Exposure (1990 NBCC, 1995 NBCC, 2005 NBCC, 2010 NBCC, 2015 NBCC)

(Revised: 11/15/2016)

Snow Exposure 1:

(a) All structures except as noted in categories 2 and 3

(b) Corresponds to a Wind Exposure Factor C_w = 1.0

Snow Exposure 2:

(a) The building is in a location such that the roof is exposed to the winds on all sides, with no obstructions higher than a distance equal to 10 times the height of the obstruction above the roof,

(b) The area of roof under consideration is exposed to the wind on all sides with no significant obstructions on the roof, such as parapet walls, within a distance of at least:

1. (SI units) 10 times the difference between the height of the obstruction and .2 times the ground snow load, or

2. (English) 32.81 times the difference between the height of the obstruction and .03846 times the ground snow load, and,

(c) The loading does not involve accumulation of the snow due to drifting from adjacent surfaces.

(d) The building is not in the High or Post-Disaster Importance Categories.

(e) Corresponds to a Wind Exposure Factor C_w = 0.75.

Snow Exposure 3:

(a) The conditions of category 2 are met and the building is located in an exposed area north of the tree line.

(b) Corresponds to a Wind Exposure Factor Cw = 0.50

See also:

§ Building Loading - Snow Load