Design Parameters for Vertical Bars (Concrete wall: EC2)
In the following, the concrete area is the gross area of the general wall, or the gross area of the mid zone if one exists. For the end zone the design criteria for a reinforced concrete column element applies.
Reinforcement area for a wall

Limiting minimum ratio of vertical reinforcement area to gross concrete area, ρ_{v,lim,min}

Limiting maximum ratio of vertical reinforcement area to gross concrete area, ρ_{v,lim,max}
Total minimum area of vert reinforcement
A_{s,min} = ρ_{v,lim,min} * A_{cg}
Total maximum area of vert reinforcement
A_{s,max} = ρ_{v,lim,max} * A_{cg}
Where 2 layers are specified distributed equally to each face, this is a minimum of A_{s,min} / 2 placed at each face.

For design to the EC2 Recommendations, UK NA, Irish NA, Malaysian NA, Singapore NA and Norwegian NA the recommended values are;
ρ_{v,lim,min} = 0.002
ρ_{v,lim,max} = 0.04

For design to the Finnish NA the recommended values are;
ρ_{v,lim,min} = 0.002
ρ_{v,lim,max} = 0.06

For design to the Swedish NA the recommended values are;
ρ_{v,lim,min} = 0.001
ρ_{v,lim,max} = 0.04
You are given additional control over these values by specifying user limits for the minimum reinforcement ratio and maximum reinforcement ratio in Design Settings.
Code Requirement cl 9.6.1
For walls subjected to "predominantly outofplane bending", the minimum area rules for "slabs" apply if they are more critical than the above, [ cl 9.3 and reference to cl 9.2.1.1 (1) (2) and (3) ], so an additional check for any value of minor axis bending is applied.
For a wall this check is:
A_{s,min} = max [(2*0.26*f_{ctm}*l_{wp}*d/f_{yk}) , (2*0.0013*l_{wp}*d) , (ρ_{v,min}*A_{cg})]
This applies for the general wall length, or the mid zone if it exists.
where
For a general wall panel length,
l_{wp} = l_{w}
Gross area of the wall, A_{cg} = l_{w}*h_{w}
For a mid zone panel length,
l_{wp} = l_{mz}
Gross area of the mid zone, A_{cg,mz} = l_{mz}*h_{w}
Effective depth of the cross section, d, is the dimension of the extreme concrete compression fibre to the centroid of reinforcement layer on the tension side, which for a wall is the line of the vertical reinforcement.
It does not apply for the end zones, since these are subject to the minimum reinforcement requirements as a column section.
Gross area of each end zone, A_{cg,ez} = l_{ez}*h_{w}
Length of each end zone, l_{ez}
Minimum Vertical Loose Bar Spacing
Clear distance between bars:^{2}
s_{cl,min} ≥ max (k_{1}* maximum bar diameter, 20mm, d_{g} + k_{2})
where d_{g} is the maximum aggregate size.
k_{1} and k_{2} are NDP values,

For design to EC2 Recommendations, UK NA, Irish NA, Malaysian NA, Singapore NA and Swedish NA;
k_{1} = 1.0, and k_{2} = 5 mm

For design to Finnish NA;
k_{1} = 1.0, and k_{2} = 3 mm

For design to Norwegian NA;
k_{1} = 2.0, and k_{2} = 5 mm
You are given additional control over the spacing by specifying a minimum clear spacing user limit in Design Settings.
Maximum Vertical Loose Bar Spacing
The limiting maximum vertical spacing, s_{v,lim,max} is an NDP.

For design to the EC2 Recommendations, UK NA, Irish NA, Malaysian NA, Singapore NA, Finnish NA, Norwegian NA and Swedish NA
s_{v,lim,max} = min (3*h_{w} , 400 mm)
You are given control over this value by specifying a maximum centre spacing user limit in Design Settings.
Footnotes