Wind on single-span gabled and hipped roofs with a slope between 7 and 45 degrees for C&C
Figure 4.1.7.6.-E (NBC2020)
v1.0.0
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:
Midheight of dominant opening (for Cei)
Midheight, hi:
m (leave empty if no dominant opening.)

Building

Roof pitch:
/12
Tributary Area, 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 dim:
m
Region
Region 'c'
Region 'r'
Region 's'
wind gable figure

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
Roof slope: 26.57 degrees

External Wind Pressure

Using figure for Gable and Hip roofs with slopes between 7 and 27 degrees.
Zone CpCg pe (kPa)
c--5-4.5
r--2.49-2.24
s--3.7-3.33
oc--7-6.3
or--1.7-1.53
os--4.2-3.78
c+0.780.7
r+0.780.7
s+0.780.7

Internal Wind Pressure

Cgi = 2
Cpi = -0.45 to 0.3
Reference height (max H/2 or 6m)= 6 m
Cei = (hi/10)0.2 (but not less than 0.9) = 0.9

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

Combined Wind Pressure

Note: Overhung roofs include contributions from upper and lower surfaces. Therefore, the interior pressures is not combined with the exterior pressure at overhangs.
Zone Cpi=-0.45
p (kPa) 		Cpi=0.3
p (kPa)
c--3.69-5.04
c+0.161.51
r--1.43-2.78
r+0.161.51
s--2.52-3.87
s+0.161.51
oc--6.3-6.3
os--1.53-1.53
or--3.78-3.78

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.