The general selection of materials during preliminary design and the refined selection during the preparation of the master plan should be based on (1) function, (2) form, (3) style/character, (4) regional climate, (5) sustainability, (6) budget, and (7) availability. Additional consideration should also be given to the clients’ preference, compatibility
with the architecture of the house, and regional appropriateness. Specifying the right material for any given element or area of the design should evolve from a thorough knowledge of materials and not be limited to the designer’s personal preference.
The appropriate material for a pavement, vertical surface, or overhead plane is partially dependent on when, how, and for how long the material is used. More specific considerations include what uses the material needs to support, whether the material is in contact with the ground, and the amount of exposure to sun, wind, and precipitation.
The shape of all elements, especially pavement, has a direct bearing on what materials are suitable. Generally speaking, forms that are rectangular are better created with modular and unit materials that are themselves rectangular in shape, whereas more curvilinear shapes are better delineated by loose and/or pliable materials that can bend to flowing edges.
The style of the house and the intended character of the landscape should be considered before selecting materials. For example, gravel, rough cut stone, and naturally weathered wood are suitable for a rustic, unrefined, rugged landscape, whereas brick, cut stone, and metal are suggestive of a polished and urban setting.
The amount, frequency, and timing of sun exposure, precipitation, frost, and even wind should have a direct bearing on material choice. Materials appropriate for a warm climate often do not work as well in a colder climate that experiences extreme temperature swings, frost, and winter snow. Similarly, dark-colored materials may be desirable in colder climates but not warmer ones because of the absorption and reflection of heat back into the air. Some materials weather fast and are slippery to walk on in areas of heavy rainfall.
As previously discussed in Chapter 3, every design proposal must consider its impact on the environment and should attempt to create a small footprint on the land. Some materials require the mining and use of scarce resources in addition to being manufactured many miles away from where they are to be used. Other materials recycle previously used materials and/or are derived from local sources. Furthermore, the toxicity and long-term maintenance of materials need to be considered.
The client’s budget is a big factor in determining what materials are suitable for a landscape design. It is a waste of time to dream about expensive materials or devise elaborate patterns and construction methods if the client is on a tight budget. Furthermore, no client wants to spend more money than necessary, so it is always advisable to select materials with cost in mind.
Only local materials or those that are easily acquired should be used in the landscape for both budget and sustainability considerations. Nevertheless, there are circumstances when a unique material or installation technique for a special feature and outdoor space warrants inclusion.