In Asphalt to Ecosystems (New Village Press, 2014), author Sharon Gamson Danks shares some of her knowledge about increasing the use of renewable energy in schools around the United States and around the world. Her methods are not only energy efficient, but they serve to educate the children within the schools as well. This excerpt, which explains how using natural resources can create an environmentally friendly school yard, is from Chapter 8, “Ecologically Sensitive Materials for Schoolyard Landscapes.”
Wood as a Natural Building Material
Wood is one of the most versatile, natural building materials for schoolyards. It can be incorporated in its roughest forms—as stumps, logs, branches, twigs, and mulch, and in its more refined form—as milled lumber. Some green schoolyards include entire trees, downed in a storm or felled by disease, as ornamental play elements. Others use portions of tree trunks, large branches, and sturdy twigs, obtained from local arborists or cut onsite, in their outdoor seating areas, stairways, and pathways.
Standard milled lumber and unprocessed logs can be purchased from many places. Look for local, sustainably harvested lumber, if possible. In my area, for example, reasonably priced, sustainably harvested dimensional lumber can be purchased from an urban mill that specializes in creating lumber from trees that local arborists remove from our region. Local arborists are also good sources for logs, branches, mulch or other wood products; often they would rather donate these materials to schools than pay a fee to dump them at a landfill.
Selecting Naturally Rot-Resistant Woods
When purchasing lumber from hardware stores and other conventional sources, do not buy pressure treated wood for use in a schoolyard—particularly for areas in or near edible gardens. Some types of treated wood contain highly poisonous substances that are intended to kill fungi and insects and resist rot—but they are also very hazardous for children. Some of the chemicals used to treat wood leach out over time and permanently contaminate the surrounding soil. Children may come into contact with these poisons by touching the wood or by inadvertently consuming the contaminated soil when they get it on their hands. Some types of pressure treated wood commonly sold in home improvement stores are banned from playground uses, but are not clearly marked as such in the store.
Similarly, it is important to avoid the use of railroad ties, which usually contain poisonous creosote, treated telephone poles, “marine grade wood,” and other chemically treated wood products. Many types of plywood are also poor choices for the schoolyard – and edible garden beds in particular—since they often contain formaldehyde and other chemical binders. Because it is often difficult to tell exactly which chemicals the wood has been treated with, and how poisonous they are, I recommend avoiding treated wood entirely in a schoolyard context. Some school districts, such as the San Francisco Unified School District, adopt a similar approach district-wide and request that their schools avoid using treated wood in their schoolyards, if possible.
Naturally rot-resistant woods such as redwood or cedar are good choices for schoolyards, if they come from sustainably harvested local sources. If these are not available, choose other hardwoods or softwoods that have shorter lifespans in the outdoor environment, and protect them with a natural finish or nontoxic stain or paint. Another good source of untreated wood is reclaimed lumber from material reuse centers or from buildings that have been carefully deconstructed. Timber from these older sources may be of a higher grade than what is currently available; old growth timber frequently has tighter grain than younger wood. Be sure to avoid wood painted with lead-based paints, however.
Over the last four years, I have worked with Rosa Parks School in Berkeley, California, to green their school grounds. Many of the schoolyard improvements, installed or handcrafted by the school community, are made of wood. For example, we used redwood logs, donated by an arborist parent, to create a sturdy and sinuous bench. The log segments, each 1.5 to 2 feet long, were installed by parents and volunteers who dug a narrow, curving trench and buried half of each log firmly in the ground. The finished project, surrounded by a soft bed of woodchips, is enjoyed by the entire school community. Leftover logs, placed in small clusters around the schoolyard, act as informal benches. We also placed a few 3-foot diameter eucalyptus tree slices, retrieved from another neighborhood tree removal project, under several bushes along the playground’s perimeter to create comfortable seats nestled in the leaves.
I worked with parents and teachers at the school to build several small garden fences adjacent to the playground, using local, sustainably harvested dimensional lumber. The Monterey cypress and redwood we selected are naturally rot resistant, but we also added a soy-based wood sealer to further extend the wood’s longevity. The new edible gardens are filled with raspberries and other crops for the children to freely “nibble” at recess. The fences define the edges of the new gardens and keep (most of!) the balls out of the plantings.
Bamboo as a Natural Building Material
Bamboo is a fast-growing plant in the grass family that is well adapted to climates ranging from tropical locations to places with snowy winters. The strong stalks, called “culms,” are hollow cylinders, subdivided into individual chambers by nodes along the stalk. Some species of bamboo form dense clumps, while others spread prolifically by sprouting from underground rhizomes. Bamboo is used in countless ways around the world to construct everything from buildings, bridges, construction scaffolding, flooring, furniture, baskets, chopsticks, and paper. Its young rhizomes are also a delicious edible food crop.
Bamboo has an appealing linear aesthetic with subtle color variations and a smooth surface. Many types of bamboo are green when they are alive, then dry to a golden yellow that fades to a weathered grey over time. In a school garden, use dried bamboo stalks to build fences, trellises, bean teepees, irrigation channels, and rain gutters.
Excerpt from Asphalt to Ecosystems: Design Ideas for Schoolyard Transformation, by Sharon Gamson Danks, published by New Village Press, 2010.