Create A Garden Or Retaining Wall

Garden walls serve many functions. They can create privacy, screen out wind and noise, define an activity area, retain sloping ground, or accent a garden design. Low walls can double as a seating platform, and taller walls provide a handsome background for specimen garden plants.

Walls impart a feeling of permanence and quality. Most walls -- especially those lower than 3 feet -- are within the homeowner's ability to build -- as long as there is some help handling the materials.

Your main considerations in planning a wall are height, materials, and structural design.

Height. The height of a wall is a critical factor in many respects. Codes and zoning ordinances set limits for wall and fence heights, usually 6 feet for side yards and backyards and 42 inches at the sidewalk line. You will probably need a building permit if you build above a certain height, typically 3 feet or more. Ordinances often require that masonry retaining walls taller than 3 feet be designed by an engineer, and some areas even require that an engineer design all free-standing walls.

Materials. Several materials work well for garden walls and create interesting effects. Choose a material that matches an architectural feature of the house or garden or that blends with the character of the area.

If you combine materials in the same wall, do not use more than 2, and use one of them sparingly. If access to the site is difficult, build with smaller units that are easy to carry. Use smaller units or irregular or rounded stones for curving walls.

Wall footings. Except those made of loose-laid stone or wood, all garden walls should be supported by a continuous concrete footing. The width and thickness of the footing depend on the size of the wall, and the depth depends on local soil conditions. Most footings are twice the depth of the wall, but the footing of a retaining wall is usually two thirds of the height of the wall. The footing should be at least 8 inches thick for a low wall; construct 12-inch footing for walls over 2 feet tall. Depth also depends on the local frost line. The minimum depth for a footing is 12 inches below grade. If a footing is deeper, some of the wall will be below grade.