Home & Garden

Use best materials for fences, walls

Fences and walls add stability, enclosure and additional design elements to a property. They mark boundaries, keep children and pets safely inside, and provide comfort and privacy.

Barriers can be inviting or intimidating. Psychologically, low barriers (three to four feet) denote privacy, but are inviting. Tall fences or walls (six to 10 feet) tell people to keep out.

Fences and walls should flow with the landscape. Don't let them dominate your property. Plantings make barriers appear less conspicuous.

If you don't want an enclosed space, use short sections of fencing spaced intermittently. A section or two around a patio or other private space may be enough to add contrast and create interest. A wide range of fencing is available in wood, metal, plastic and recycled materials.

Most jurisdictions require a building permit before fences can be installed. Call your local government to find out rules on height and other requirements.

Here are some ways that I have built fences and walls:

* Crushed gravel base: The best method for do-it-yourself fence installation because it is done dry, without concrete, and can hold fence posts firmly. Wooden fences are especially susceptible to rot at ground level. Concrete can hold moisture around a post and encourage decay.

To set a wooden post, place the pressure-treated four-by-four inch or six-by-six inch post two feet into the ground, digging a hole with a posthole digger or auger. Tamp three-quarter-inch to inch-and-a-half size crushed gravel firmly in the hole around the post to keep the area well drained. This will also hold the pole solidly in place and keep it from rotting. Use a level to keep the post plumb — that is, perpendicular to the ground.

* Concrete base: Sometimes it's not practical to use stone because it will not set the post securely enough. Concrete can be poured any thickness and depth depending on the sturdiness required. Metal poles must be anchored in concrete for chain-link fences. Tightly stretch the fence from one post to another, after the concrete has hardened, and only if it withstands the tension.

Walls add beauty to gardens, and low ones can double for seating, although they do not provide as strong a spatial enclosure as a fence. Using them to retain banks and slopes will add strength to designs. They can turn slopes into multilevel terraces. Grade changes are interesting elements, and retaining walls add horizontal stability. Such walls must be able to withstand hundreds of pounds of pressure from the weather pounding down on the soil.

Mortar masonry walls built to function as retaining walls must be built on concrete footings. Masonry walls mortared together must not move or lean. They need to be perfectly plumb. This rule applies to all mortared walls. Start these structures on concrete footings. They should be poured on undisturbed soil below the freeze line. Footings average 24 to 30 inches deep.

The following materials make excellent retaining walls and are conducive to dry installation:

* Concrete block retaining wall systems: These have received excellent reviews from construction firms and agencies that regulate construction. Most lock together and lean into the bank slightly, with lots of natural weep holes and provisions for drainage stone. Search the Internet using the words "garden walls."

* Pressure treated six-by-six inch ties: In six- to eight-foot lengths, these are effective in retaining a bank of soil. To level the ties, begin the first course on a layer of sand or stone. Drill and stake the ties with 12-inch spikes as they are laid into place. Batter the wall into the bank. Use "dead-men" to secure a wall more than 18 inches tall. A "dead-man" is a tie that is attached to the retaining wall and runs perpendicular into the bank. It is attached to a crosspiece set four to five feet into the bank, and then buried in soil.

* Dry-stack fieldstone walls: Easiest to maintain. If rocks fall down, the pieces that fell down can easily be picked up and put back together again. Stone stacked without mortar is versatile. It fits the landscape and offers natural weep holes that can be planted. Use rocks of a similar shape, and take time to assess how each one will fit its space. Careful laying of stone is noticeable in the finished product.