Why do large cracks in foundation block not crack the brickwork in front as badly?
One would think that since brick is a far more dense and brittle material that it would crack worse than concrete block. The answer is actually rather simple. There are six brick to every on concrete block. Mortar offers the flexibility in a masonry wall system. The considerably higher percentage of mortar in the brick wall system minimizes cracking.
Hi. Mike;
Guessing and off the cuff, I would have to say that block work is soft and dose not offer so many mortar joints to bond and relieve the stesses of the lateral pressures exorted to the wall system. Brick is more dense and has more mortar joints to absorb the stresses.
The type of masonry mortars used will also play a big role in this issue. Type M is a soft pliable mortar and adheres good to bricks. Type S is a structural grade and tends to be good in structural capacities but poor in flexible properties.
Hope this helps.
Marcel 
Hmmm, a question that comes with an answer?:p;-)
Are you thinking to yourself while typing??:p:p
Hey Marcel,
Actually, type “M” is the strongest of all mortars. From weakest to strongest it goes like this: O N S M
Just having fun sharing, Todd. Hope you enjoy.
