Roofs with slope of 7 degrees or less.

Figure 4.1.7.6.-C (NBC2020)

v1.0.1

Climatic Data

Location Custom

Source

Region

Location link

Velocity Pressure

Return Period:

Reference Velocity Pressure

kPa

Factors

Importance factor

Category:

Limit state:

Exposure Factor

Terrain:

Height, h:

m (Reference height in meters above grade)

Topographic Factor

C_t:

Internal pressure

Category, C_pi:

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:

Zones

Zone 'c'

Zone 'r'

Zone 's'

Factors

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

External Wind Pressure

Zone	C_pC_g	p_e (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+	0.5	0.45
r+	0.5	0.45
s+	0.5	0.45

Internal Wind Pressure

C_gi = 2

C_pi = -0.45 to 0.3

p_i = I_w*q*C_e*C_t*C_gi*C_pi
p_i = -0.81kPa to 0.54kPa

Combined Wind Pressure

Zone	C_pi=-0.45 p (kPa)	C_pi=0.3 p (kPa)
c-	-5.4	-4.05
c+	-0.09	1.26
r-	-2.16	-0.81
r+	-0.09	1.26
s-	-2.16	-1.44
s+	-0.09	1.26
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.