Roofs with slope of 7 degrees or less.
Figure 4.1.7.6.-C (NBC2020)
v1.0.1
File:
Project:
Designer:
Date:

Climatic Data

Location
Province:
Reference Velocity Pressure
q:

Factors

Importance factor
Category:
Limit state:
Exposure Factor
Terrain:
Height, h:
m (Reference height in meters above grade)
Topographic Factor
Ct:
Internal pressure
Category, Cpi:

Building

Area of surface, A:
m2
Roof has overhang:
End-zone width, z
(If H or the least horizontal dimension are left blank, z will not be calculated.)
Building Height, H:
m (Height of building at eave)
Least horizontal dimension:
m
Zones
Zone 'c'
Zone 'r'
Zone 's'
wind walls

Factors

User input values:
q: 1kPa
Importance Factor, ULS: Iw = 1.0
Ce = (h/10)0.2 (but not less than 0.9) = 0.9

External Wind Pressure

Zone CpCg pe (kPa)
c--5.4-4.86
r--1.8-1.62
s--2.5-2.25
oc--5.4-4.86
os--3.2-2.88
or--3.2-2.88
c+0.50.45
r+0.50.45
s+0.50.45

Internal Wind Pressure

Cgi = 2
Cpi = -0.45 to 0.3

pi = Iw*q*Ce*Ct*Cgi*Cpi
pi = -0.81kPa to 0.54kPa

Combined Wind Pressure

Zone Cpi=-0.45
p (kPa) 		Cpi=0.3
p (kPa)
c--5.4-4.05
c+-0.091.26
r--2.16-0.81
r+-0.091.26
s--2.16-1.44
s+-0.091.26
oc--5.4-4.05
os--3.42-2.07
or--3.42-2.07

End Zone Width

The end-zone width is the lesser of:
• 10% of the least horizontal dimension = 0.1m
• 40% of the height of the building (H) = 0.4m
but not less than:
• 4% of the least horizontal dimension = 0.04m
• 1m
z = 1m

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.