requirement of vertical joints in parapet walls

huangyhg

requirement of vertical joints in parapet walls
need to know about requirement of joints in exterior parapet walls for two conditions as attached, as i observed some cracks if the joints are avoided in parapet walls. what type of vertical joints are required for these two cases:

it depends on the material that is being used for the wall as well and many other local factors.  
it appears to be cast-in-place concrete...if so, then i would use a maximum of 20 feet, mostly because of the apparent height-to-length ratio and the potential for unsightly shrinkage cracks.  structurally, you don't need control joints any closer than about every 100 feet, or to coincide with structural control joints in the building.
if masonry, coincide with structural joints
if wood with cladding, about every 20 feet. if stucco, every 18 feet to comply with most codes.
all of your joint configurations will depend on materials, max-min temperature range, aspect ratio, and structural necessity.
it's a parking garage strcuture exposed to weather. parapet height is 3'-6" app.
does the wall need to be separate from columns, as for case-b. as this would be 6" conc. wall and we are placing rebars in a single layer.