406 Landscape Design, Installation, and Management Copyright Goodheart-Willcox Co., Inc. The materials used in hardscapes and the design itself should complement the home and softscape. Some materials lend them- selves to more formal and structured patterns where others can be used to create less formal and even whimsical patterns. Many of the patterns used when laying stone, paver, or brick walkways, driveways, and patios can be identifi ed by name. A designer using pavers or wood will often place a soldier course (a repetition of the same material in the same pattern) around the edge of a hardscape area. This design uses the material in a one right after the other pattern and visually provides a border. A pattern would then be placed within the soldier course, creating more visual emphasis on the inside pattern. Water Flow When creating a landscape design, the designer must consider the fl ow of water as it contacts the surface of each hardscape mate- rial used in the design. Textured and rough surfaces often provide enough traction when wet. However, smooth surfaces may become hazardous in wet conditions. The permeability of a material will also affect water fl ow across the landscape. Permeability The permeability of a landscape material is measured by the amount of water it allows to pass through to the ground below. Materials that are more permeable include mulch, stone aggregates, and turf or groundcover, Figure 15-11. Areas covered with these materials will not defl ect water unless the ground is completely sat- urated. Water that seeps into the ground will resupply groundwater. When using less permeable materials in a design, such as concrete, a designer must consider not only the safety factor but also where water will fl ow when it hits the surface. Permeable brick or concrete pavers are constructed with vertical spacer bars on the edges that create a space between the units and allow water to permeate into the soil below. Porous material, such as sand, is used between the units. This porosity also helps prevent cracking or shifting of hard- scape materials during the freeze-thaw cycles of winter. Slope To ensure water will be directed in the desired direction, impermeable hardscapes must have at least a 1% slope. (Slope is the rise and fall of the land surface or a change in elevation from a fi xed point.) Incorporating suffi cient slope to an impermeable hardscape will ensure that water will be directed in the desired direction. The area to which the water is directed could be the lawn at the edge of a patio, fl ower/plant beds, a pond, or a storm drain. The slope of the lawn will direct overfl ow to the storm drain or other natural waterway. In some designs, water is directed to a sub-drainage system. A sub-drainage system is a low-impact design that allows the water from the hardscape to fl ow into the groundwater supply. A sub-drainage system is piping below ground level that helps water drain from hard surfaces. An example would be to place a course Lallcreative/Shutterstock.com Figure 15-11. Hardscapes designed for water permeability enable rainwater to return to the ground and prevent it from channeling into storm drains or other offsite areas. jeep2499/Shutterstock.com T.Nikandrov/Shutterstock.com