Guidance for masonry control joints can be found in NCMA TEK 10-3. This guide outlines an engineering approach to controlling cracking in masonry walls. The guide covers BOTH Methods:
1. use minimal reinforcement and control joints
AND
2. use horizontal reinforcement only
Obviously the latter requires more reinforcement.
Method 1 would result in control joints (CJs) at 20-25 feet on center and a reinforcement ratio of 0.0007. This results in horizontal joint reinforcement (generally wire reinforcement in mortar joints) in ungrouted or partially grouted walls at 16″ spacing. Note: reinforcement spacing can be larger for thinner walls or if larger joint reinforcement is used.
REFERENCE: NCMA TEK 10-3 Table 2
Method 2 would result in masonry with a reinforcement ratio of 0.002 (three times more than Method 1). This results in horizontal bond beams with bar reinforcement at 48″ spacing or less. Note: reinforcement spacing may need to be smaller for thicker walls or when walls are grouted solid.
REFERENCE: NCMA TEK 10-3 Table 3