Yard and Garden Column for the Week Beginning April 8, 2005
By Ann Marie VanDerZanden
Associate Professor of Horticulture
Iowa State University
Most residential landscapes include a combination of hardscapes (patios, decks, walkways and driveways) and ornamental plants. As you think about the design, construction and maintenance of your overall landscape, consider how you could make each component more sustainable.
The principles of sustainability; reduce, reuse and recycle, apply to landscapes and can be achieved in a variety of ways. Reduce the amount of virgin materials used in the landscape. Reuse existing materials when possible, or select recycled products. Additionally, a number of new recycled landscape products are available. Many of them are made from recycled plastics combined with wood by-products. These materials require virtually no maintenance and have a longer life span than wood, can be used for decks, fences, benches and planters, and come in a variety of textures and colors.
It is often easier to evaluate the initial cost of construction materials than it is their long-term maintenance costs. However, the long-term maintenance costs of some building materials can be significant. Before you choose a product, research the initial and long-term costs as well as its recommended uses. Using a product improperly may not only be dangerous, but will likely increase your overall construction and maintenance costs. You should also check local codes and regulations to make sure the product you select is approved for use in your area.
The hardscape options listed below vary in their sustainability and short and long-term costs. For specific information on these materials consult a landscape construction reference or a landscape contractor.
Porous paving: This material can be used for driveways, walks or patios. It allows for water infiltration while providing a solid surface that can handle human and vehicular traffic.
Concrete Pavers: These pavers are durable, easy to install and allow for water infiltration. They come in a wide range of colors and shapes and can be used for drives, walks, patios and even sunroom or porch floors. Because they come in uniform sizes and shapes they are relatively easy for a homeowner to install.
Concrete slabs: The set up for pouring a concrete slab can be labor intensive but the actual cost of the concrete is relatively inexpensive. However, the slabs are susceptible to cracking and are expensive to repair. For most homeowners, concrete pavers are a viable alternative to a concrete slab.
Soil Cement: A relatively new process that uses a small percentage of Portland cement mixed with native soil on site. It has about 2/3 the compressive strength of ordinary concrete, but is suitable for walkways and patios. And, in naturalistic settings it has an aesthetic advantage over pavers, bricks, or concrete slabs.
Wood: Decay resistant species such as Redwood are in short supply, generally harvested from ecologically sensitive forests and often expensive. Using redwood that has been salvaged from other structures is a sustainable choice. Treated landscape lumber is readily available, and if maintained properly can last 15-20 years. The safety of wood preservatives has been a subject of much controversy, particularly as it relates to disposal, accidental burning of the wood and leaching of the products into the soil. The methods and chemicals used to treat landscape lumber vary and you should consider these before you purchase a product.
Composite Wood: These products are relatively new for homeowners, but have been available commercially for more than 15 years. A number of manufacturers make these products, which results in variability in their composition. In general, they all resist rot and insects and can substitute for preservative treated wood. They can be used for decks, fences and even some outdoor structures such as a gazebo. If using this product for a structure, be sure to check that it is rated for such a use.
Thoughtful consideration of hardscapes can significantly increase the sustainability of your landscape. Remember that a landscape is a long-term investment and you must consider upfront and long-term costs, both financially and to the environment, when you design and construct your landscape.
For a comprehensive discussion of constructing sustainable landscapes, refer to Sustainable Landscape Construction: A Guide to Green Building Outdoors by J. William Thompson and Kim Sorvig.