Q: What is the “greenest” fence to use?
A: When it comes to sustainability options, we often focus solely on the house. But when looked at as a whole, there’s a lot of material spread around our yards and over our country that, like a home itself, certainly has some sort of impact on our footprint on the planet. Let’s look at why we need fencing, the current options, and how our fencing choices could possibly be more sustainable, thereby reducing our footprint on the resources of our big round home we’ve named Earth.

Fences work for us. They keep things in, keep them out, or create privacy. Some fences perform all three tasks. Once you’ve decided the purpose your fence will serve, you need to decide what material you will use, the area to be fenced and your budget.

Common fencing options include metal, such as chain link, welded wire or steel stock in a round or square shape; wood in the form of pressure-treated or rot-resistant pickets, slats or boards; and plants—perhaps the “greenest” choice—in the form of privacy hedges. Other materials can be used to create fences, too; you may see them as you drive around our community. Any material that is fairly ridged, has a resistance to rot and is easy to erect can make a fine fence. I have noticed locally obtained materials like bamboo poles, old barn wood, rhododendron branches from cleared construction sites and even scrap steel become effective fences.

Instead of assessing all of the possible materials one by one in this response, let’s look at some of the criteria that make a material sustainable.

Embodied energy—How much energy went into creating the material? Metal fences, such as chain link and welded wire can be very secure, but steel needs a large amount of energy to be created. Wood and recycled materials do not. Transport can also increase the embodied energy of a product. The less energy needed to produce and ship a material, the smaller the environmental footprint of the product, and therefore the more sustainable it is.

Local resources—If a material can be obtained locally, it doesn’t have the embodied energy of shipping and storage. It can also promote the local economy and support your neighbors’ businesses. We have wonderful sources of local wood fence materials, such as locust, hemlock and bamboo, in our backyards. Of the three, locust will last the longest, bamboo the shortest.

Longevity—If a fence lasts a long time, it won’t require replacement materials and energy. Materials for fences need to be rot-resistant, as all sides are exposed to the elements. Steel is the best option here, but as mentioned above, it has some unsustainable qualities.

Maintenance—Materials that need maintenance aren’t the best choice. Untreated softwoods will fail due to rot or exposure. Having to paint or waterproof wood takes time and money and can also introduce unwanted chemicals into your yard.

Toxicity—Many wooden fences are pressure treated with a number of chemicals. Although the new treatment methods are not as toxic as they used to be, it’s better to keep them out of your yard. If using wood, try to find softwoods that have been treated through a process called “wolmanizing,” or use some of the local rot- resistant wood species in our Appalachian forests, like locust.

Once the fence materials have been selected, there are two more choices to make: how the materials are going to be anchored to the ground and what method will be used to fasten the materials to the structure. Posts are usually embedded in the ground to support the material. The posts need to be made of a material that can be below grade for a long time. Pressure-treated wood is the most common, but locust and steel will work well also. Concrete does not have to be used to support the posts in the ground. Tamping the soil around the post as the hole is being filled will provide strong support and eliminate concrete and its high embodied energy. Depending on the material, exterior rated screws are usually the best form of fastening the materials together. Any material, especially wood, will warp over time due to expansion and contraction from the changes in temperature, water and the sun.

And don’t forget the gate! Purchase good hardware that can last a long time. Gates can be heavy, and they get a lot of traffic. Consider using another material for the gate if your fence choice isn’t the best gate material.

Marcus Renner regularly teaches classes for the Western North Carolina Green Building Council, is a consultant with Appropriate Building Solutions, Inc. and enjoys staying up late debating the intricacies of building science. He’s also a member of the New Life Journal Green Home Experts Board and can be reached at marcus@abuildingsolution.com or 828-713-3346.

*We know that this month’s issue is about encouraging interaction between neighbors and tearing down fences, metaphorically speaking. But, just in case that neighbor’s dog won’t stop spreading your compost pile around the block, NLJ wanted to be sure your fence could be built with the Earth in mind.

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