Vertical enclosures include structures, screens, and plants of different heights and varieties. Low railings, low solid walls, and seats, serve as enclosures without obstructing the view. Wire mesh fences, latticework, or stiff thorny plants may be used to keep children or dogs in or out of an area.
Some enclosures do not obscure the view. Among them are trellis or lattice frames, with or without glass or other fillers; rows of poles; louvered, split-wood, or other open-joint fences; and masonry provided with openings. Taller barriers of solid wood, masonry, or sheet materials are used to block both vision and movement.
Enclosures may consist of wood, masonry, sheet materials, or vegetation. They may be of split, rough-sawn, or finished lumber; concrete block; tile; stone; poured concrete; or stucco on a wood frame or on concrete block. They may be of sheet materials such as plywood, glass, plastics, or metal. Trees and shrubs often make the best enclosures, particularly shrubs that grow erect and have little spread. If privacy cannot be obtained with plants, structural enclosures are used.
Walls are used to define areas, to ensure privacy and protection, to hold up earth, and to serve seating purposes. The requirements of masonry walls are stability and attractive appearance. For stability, the foundations of any masonry wall should extend below the frost line.
Stone, brick (with or without mortar), and concrete are among the most favored materials for walls. The easiest stones to use for walls are of stratified horizontal limestone, shale, or sandstone. They split and chip rather readily, however, unless mortared solidly to prevent water infiltration. Granites, on the other hand, are tough and durable. Brick walls have many uses and offer attractive possibilities in texture and color.
There are two kinds of stonework: 1) the rubber type, in which uncut stones are fitted into the wall in a natural, irregular pattern, with no continuous joints, and 2) the ashlar type, in which cut stones are placed in regular courses.
The stones when placed should produce harmonious and pleasing patterns. A large proportion of the more sizable stones should appear in the lower courses. Stones of the same shape should be kept apart; they should not be placed side by side. To ensure proper bonding, each long stone should be overlapped by two smaller ones.
Dry walls are built of flat stones fitted together without the use of mortar. Some dry walls are free-standing; others are built to retain earth. High dry walls require large stones throughout. Such walls must not be more than 4 to 5 feet high, and must be at least 2 feet thick at the top, with the bottom somewhat thicker for stability. When these walls are built to retain earth, the stones must be placed with the back ends tipped into the ground and the stones slanting slightly upward toward the front. The crevices are filled with rich soil and plants. Retaining walls generally need provisions for carrying water through or around them, such as ditches, gutters, drain tile, weep holes, or gravel backfill.