In the tool menu select 'Shape'.
In the Alt menu select 'Box'.
Hold Ctrl and drag the size to 2x4.
Place columns next to each other.
When placing them in an oblique (middle set), place 1x4 columns to fill in the deep angles (right set).

When you want to smooth out the wall select 'blockify' in the tool menu.
Adjust the brush size to ~4 with Ctrl.
Hold left-mouse button over wall sections and drag along wall and near bottom of wall on both sides.