You’ll obviously need to call in a professional if the situation is urgent (rainwater is pouring through the ceiling, say) or you’re in the process of moving and the sale of your home is contingent upon making the repairs. It also pays to take action if you’re planning on staying in your house for five years or longer, since home values may rebound by then, or if the problem is currently small and relatively cheap to fix but could snowball into something bigger and badder if left unaddressed (a leaky toilet, a furnace pilot light that won’t stay lit). That said, in today’s weak housing market, you should avoid spending more than is absolutely necessary on fixes if you’re going to move prior to 2016. “Be careful not to over-improve your house—for example, by installing a new, $45,000 slate roof on a modest home,” says David Crook, the author of The Wall Street Journal Complete Real-Estate Investing Guidebook ($15, amazon.com). “In most cases, you won’t be able to recoup the costs.”