Badly cracked up chimney bricks

These cracks are caused by rebar originally installed during construction to give strength to the chimney. Lack of maintenance, waterproofing, allowed moisture to penetrate to rebar and the expansion rusting rebar shatters chimney bricks. Extensive cracking due to lack of maintenance. Because chimney bricks are porous, water can soak through to rebar. Metal as it rusts, expands and blows up bricks.