Site Class
Ground Profile Name
Average Properties in Top 30 m
Average Properties in Top 30 m
Average Properties in Top 30 m
Average Shear Wave Velocity, 
(m/s)
Average Standard Penetration Resistance, 
Soil Undrained Shear Strength, su
A
Hard rock(1)(2)
> 1500
N/A
N/A
B
Rock(1)
760 < 
≤ 1500
N/A
N/A
C
Very dense soil
and soft rock
360 < 
< 760
> 50
su > 100 kPa
D
Stiff soil
180 < 
< 360
15 ≤ 
≤ 50
50 kPa < su ≤ 100 kPa
E
Soft soil
< 180
< 15
su < 50 kPa
Any profile with more than 3 m of soil with the following characteristics:
• plasticity index: PI > 20
• moisture content w ≥ 40%, and
• undrained shear strength: su < 25 kPa
F
Other soils(3)
Site-specific evaluation required
Column 1
2
3
4
5
Notes to Table 4.1.8.4.A.:
(1) Site Classes A and B, hard rock and rock, are not to be used if there is more than 3 m of softer materials between the rock and the underside of footing or mat foundations. The appropriate Site Class for such cases is determined on the basis of the average properties of the total thickness of the softer materials. (See Appendix A.)
(2) If 
has been measured in-situ, the Fa and Fv values derived from Tables 4.1.8.4.B. and 4.1.8.4.C. may be multiplied by (1500 / 
)1/2.
(3) Other soils include:
(a) liquefiable soils, quick and highly sensitive clays, collapsible weakly cemented soils, and other soils susceptible to
failure or collapse under seismic loading,
(b) peat and/or highly organic clays greater than 3 m in thickness,
(c) highly plastic clays (PI > 75) more than 8 m thick, and
(d) soft to medium stiff clays more than 30 m thick.