Roof Snow Load
(NBC 2020)
v1.0.0
File:
Project:
Designer:
Date:

Climatic Data

Location
Province:
Ground snow load
Ss:
Rain Load
Sr:

Factors

Importance Factor, Is:
Basic Roof Factor, Cb:
If Cb left blank, provide the dimensions in the roof geometry to compute Cb
Wind Factor, Cw:
Accumulation Factor, Ca:
(If Caleft blank, Ca will be computed assuming gable roof)
Roof Geometry
Pitch:
/12
Slippery:
Roof Plan dimensions
Dimensions used to calculated Cb if Cb left empty.
Longer dimension, l:
m
Shorter dimension, w:
m
snow gable figure

Specified Snow Load

[4.1.6.2]
S = Is[Ss(CbCwCsCa)+Sr]

Factors

User input values:
Ss = 1 kPa
Sr = 1 kPa
Importance Factors:
ULS: Is = 0.8
SLS: Is = 0.9
Cb = 0.8 (based on input Cb
Roof slope = 0 degrees
Slope Factor
For non-slippery roof:
Slope <= 30 degrees: Cs = 1
[Table A-4.1.6.9]

Snow on Gable Roofs

Load Case I

Same load on both upwind and downwind sides.
ULS:
Cw = 1
Ca = 1

S = 1.44 kPa ( 30.1 psf )

SLS:
Cw = 1
Ca = 1
S = 1.62 kPa ( 33.8 psf )

Load Case II

Load Case II does not apply to gable roofs with slopes of 15 degrees or less.

This information must be read or used in conjunction with Part 4 of the NBC 2020. In the event of discrepancies, Part 4 of the NBC 2020 shall govern.