Spalled Brickwork is when the expansion of freezing water breaks off the top surface of a brick, leaving the inner surface exposed. After a number of cycles of expansion the brick will crumble completely.
Bricks have a porous interior which becomes exposed to water once the brick fascia has 'spalled' or broken off.
Spalled Bricks are highly absorbent and can absorb as much as a pint of water per brick. Further freezing of this water will cause the brick to fail or crumble and the best means to rectify the problem is to replace all Spalled Bricks with new ones.
Spalled brickwork is fairly common on older brick constructed properties and would be noted on a HomeBuyers Report or Building Survey.