A poorly worded or vague contingency clause in one's sales contract could end up costing lots, maybe even your new home. Contingency clauses allow buyers to back out of contracts should they be unable to fulfil certain conditions such as the successful sale of their own properties, the securing of suitable financing, having the property pass inspection or having a boundary survey done.
They therefore protect a buyer, should he be unable to deliver on his intention to buy the property. Most professional estate agencies have pre-printed contracts which comply with the legal requirements for a contingency, but changes should not be made unless one is using an experienced estate agent or an attorney.
Article on rodneyhayter.com