A solid-wood exterior door should last as long as the house it hangs in. You can fix most problems yourself, and do so economically, especially when the cost of a new wood door can easily top $1,000. If, for instance, you feel a winter chill when you run a hand around the door's perimeter, your first defense is new weatherstripping. The old stuff gets stiff and cracks with age. For gaps smaller than ¼ inch, a 17-foot roll of closed-cell vinyl foam tape—enough to insulate any size door—will seal air leaks for less than $7. Bigger gaps require a new doorjamb kit and matching sweep for the bottom, and will run you $25. A sagging or ill-fitting door should be rehung first to ensure it's centered correctly in the frame, says Michael Dresdner, a wood restorer in Puyallup, Washington. But if your door is warped or isn't built to endure your climate, get a new one. In areas with extreme temperature fluctuations, for example, a wood door with multiple panels that can expand and contract within their frame will outlast a slab style.