That thin skin of resin and pigment also protects your investment, shielding it from sun, wind, and rain—until the paint begins to crack and peel, that is. Then it’s time to button up with a couple of new coats. Properly applied, new paint should last for a good 15 years, provided you use top-quality materials, apply them with care (and with an eye on the weather), and, most important, clean and sand every surface first. Here’s what you need to know to get a first-class finish on your home’s exterior.