Wrack is when something falls into disrepair. When an old house deteriorates, you can describe its wrack, or the process of its crumbling collapse.
You're most likely to come across the noun wrack in the phrase "go to wrack and ruin." This is a descriptive way to talk about the collapse or gradual breakdown of something, either literal — "I hate to see that building go to wrack and ruin," or figurative — "Their marriage went to wrack and ruin after a year." In the fourteenth century, a wrack was a shipwreck, from the Middle Dutch wrak, or "wreck."