Sand fences trap wind-blown sand. The fences reduce wind speed near the ground, thereby causing the wind to deposit sand in a mound on the downwind side of the fence. As the sand deposit grows, the fence loses its effectiveness in slowing the wind. Additional fences may be necessary or the growing deposit can be planted with vegetation that will continue to trap sand. Fences are often left in the deposit to be fully buried because their removal is difficult.

One use of sand fences is to create new dunes or dune features. Fences places above the high water line on a sandy beach will start the process of building a foredune. Fences placed across gaps or small blowouts in dune ridges will begin the process of filling in the gap.

Sand fences across the beach in North Beach Park (Ottawa County, MI) will trap sand and snow during the winter. These fences are installed in the fall and removed in the spring to reduce the amount of wind-blown sand moving into the parking lots. (October 2004)

People also use sand fences to stop sand movement. A carefully-placed fence can halt the movement of sand before it reaches a boardwalk or parking lot, or before wind-blown sand moves across the top of a dune. When fences are protecting structures, enough room must be left between the fence and the structure for sand accumulation.

The most effective sand fences are placed perpendicular to the dominant direction of sand movement. A good target porosity is 50%; fences that are too porous let too much sand and wind through, and fences that are not porous enough may produce erosion as the fence changes local wind patterns. Branches or reed stakes may be used to create biodegradable 'fences'.