Surfacing Materials

Surfacing materials form floors for the outdoor room. While top-quality turfgrass would be the first choice of most people as the most attractive and comfortable surfacing, it will not withstand concentrated foot traf­fic and tolerates very little vehicular traffic. Groundcover and flowers are also attractive surfacings, but their use is aesthetic; they will tolerate

no traffic of any type. Therefore, the need for constructed surfacings is firmly established in the landscape industry.

Depending on their degree of durability and their physical struc­ture, constructed surfacings are categorized as either hard pavings or soft pavings. The terms have little to do with the comfort of walking on them.

Hard pavings are either poured or set into place as modular units, and become solid when installation is completed. Examples include decking, poured concrete, precast concrete slabs, brick, cobblestone, flagstone, and an ever-expanding selection of precast interlocking units that permit the creation of highly decorative patterned pavings.

Soft pavings are loose aggregate materials, sometimes finely par­ticulate like sand, sometimes coarsely particulate like crushed stone

pr TABLE 9-8. ] A Comparison of Surfacing Materials

Material Description

Hard Paving Soft Paving

Modular

Continuous and Solid

Asphalt: A petroleum product with adhesive and water-repellant qualities.

It is applied in either heated or cold states and poured or spread into place.

Semihard; allows weeds to germinate and grow through it

Asphalt Pavers: Asphalt combined with loose aggregate and molded into square, rectangular, or hexagonal shapes. They are applied over a base of poured concrete, crushed stone, or a binder.

Semihard if not applied over concrete

Brick: A material manufactured of either hard baked clay, cement, or adobe. While assorted sizes are made, the standard size of a common brick is 21/2 X 33/4 X 8 inches.

Brick Chips: A by-product of brick manufacturing. The chips are graded and sold in standardized size as aggregate material.

Carpeting, Indoor/Outdoor: Waterproof, synthetic fabrics applied over a concrete base. They are declining in popularity. Their major contribution is to provide visual unity between indoor and outdoor living rooms.

Clay Tile Pavers: Similar to clay brick in comparison, but thinner and of varying dimensions (most commonly 3 X 3-inch, or 6 X 6-inch squares). They are installed over a poured concrete base and mortared into place.

or brick chips. They may be hard and virtually indestructible or may shatter, pulverize, and even decay. Examples include sand, crushed stone, brick chips, marble chips, stone dust, wood chips, tan bark, sawdust, and asphalt. All are temporary, either because of deteriora­tion or because they are easily carried away on shoes and tires. They may be dusty when the weather is dry, sticky in the case of asphalt, and tracked into the house if used near doorways. Soft pavings are seldom satisfactory as surfacings for areas that receive intensive use, such as patios or entrance walks. However, they are well suited to areas where grass is impractical yet the expense of hard surfacing is unwarranted, such as secondary walks, dog yards, service areas, and children’s play areas.

Table 9-8 compares commonly used landscape surfacing materials.

Slippery When

Permeable to

Suitable for

Suitable for

Wet

Water

Vehicles

Walks

Suitable for Patios

Certain formulations are suitable. Others may become sticky in hot weather.

Note: The application of a soil sterilant before applying the asphalt can eliminate the weed problem in walks, drives, and patios.

If installed over crushed stone

If installed in sand

Edging needed to hold them in place

Provision must be made for surface water drainage or the carpeting becomes soggy

(continues)

TABLE 9-8.

A Comparison of Surfacing Materials (Continued)

Material Description

Hard Paving Soft Paving Modular

Continuous and Solid

Concrete: A versatile surfacing that can •

be made glassy smooth or rough. It can

also be patterned by insetting bricks, wood strips,

or loose aggregates into it. Concrete

is a mixture of sand or gravel, cement, and water.

It pours into place, is held there by wood or steel forms, then hardens.

Crushed Stone: Various types of stones are included in this umbrella term: limestone, sandstone, granite, and marble. Crushed stone is an aggregate material of assorted sizes, shapes, and durability.

Flagstone: An expensive form of stone rather than a kind of stone. Flagstone can be any stone with horizontal layering that permits it to be split into flat slabs. It may be used as irregular shapes or cut into rectangular shapes for a more formal look.

It is usually set into sand or mortared into place over a concrete slab.

Granite Pavers: Granite is one of the most durable stones available to the landscaper. The pavers are quarried cubes of stone,

3 1/2 to 4 1/2 inches square, that are mortared into place. Various colors are available

Limestone: A quarried stone of gray coloration. Limestone can be cut to any size. It adapts to formal settings.

Marble: An expensive quarried stone of varied and attractive colorations. It has a fine texture and a smooth surface that becomes slippery. Its use as surfacing is limited. It can be inset into more serviceable surfaces such as poured concrete.

Marble Chips: A form of crushed stone, marble chips are more commonly used as a mulch than a surfacing. They are expensive compared to other loose aggregates; still they enjoy some use as pavings for secondary walks and areas that are seen more than walked upon.

Slippery When Wet

Permeable to Water

Suitable for Vehicles

Suitable for Walks

Suitable for Patios

Only when

smoothly

finished

Edging needed to hold the material in place

Limited use except beneath picnic tables where stains might spoil hard paving

Depends upon the rock used and how smooth the surface is

Too rough

Best used in dry climate where slipperiness will not be a frequent concern

(continues)

Patio Blocks: Precast concrete materials available • in rectangular shapes of varied dimensions and colors. Limitless patterns can be created by combination of the sizes and colors. The blocks are set into sand or mortared over concrete.

Sandstone: A quarried stone composed of •

compacted sand and a natural cement such as silica, iron oxide, or calcium. Colors vary from reddish brown to gray and buff white. The stone may be irregular or cut to rectangular forms.

Slate: A finely textured stone with horizontal • layering that makes it a popular choice for flagstones. Black is the most common color, but others are available.

Stone Dust: A by-product of stone quarrying.

Stone dust is finely granulated stone, intermediate in size between coarse sand and pea gravel. It is spread, then packed down with a roller. The color is gray.

Tanbark: A by-product of leather tanning. The material is processed oak bark. It has a dark brown color and a spongy, soft consistency. It is ideal for children’s play areas.

Wood Chips: A by-product of saw mills, wood chips are available from both softwoods and hardwoods. The latter decompose more slowly than the former. Wood chips have a spongy, soft consistency. They are often used as mulches.

Wood Decking: Usually cut from softwoods, •

the surfacing can be constructed at ground level or elevated. The deck is valuable as a means of creating level outdoor living spaces on uneven terrain. Space should be left between the boards to allow water to pass through and the wood to dry quickly. Use of a wood preservative will slow decay.

Wood Rounds: Cross sections of wood cut •

from the trunks of trees resistant to decay, such as redwood, cypress, and cedar. The rounds are installed in sand. Individual rounds are replaced as they decay.

Slippery When Wet

Permeable to Water

Suitable for Vehicles

Suitable for Walks

Suitable for Patios

Edging needed to hold the material in place