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Plastic Lumber Landscaping Timbers and Posts

Landscaping timbers and posts are used as raised beds, retaining walls, and terracing. Plastic lumber landscaping timbers and posts are used in urban plazas, zoos, and outside office buildings-in fact, the National Park Service alone has more than a dozen projects planned with these recycled-content products. Timbers and posts manufactured with plastic or composite (plastic mixed with wood or fiberglass) lumber give new life to recovered wood and plastic materials such as milk jugs and plastic bags.


Recommended Recovered Materials Content Ranges:

EPA's Recovered Materials Advisory Notice (RMAN) recommends recycled-content levels for purchasing plastic lumber landscaping timbers and posts as shown in the table below.

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EPA's Recommended Recovered Materials Content Levels for Plastic Lumber Landscaping Timbers and Posts ¹
Material Postconsumer Content (%) Total Recovered Materials Content (%)
HDPE 25-100 75-100
Mixed plastics/Sawdust 50 100
HDPE/Fiberglass 75 95
Other mixed resins 50-100 95-100

¹EPA's recommendations do not preclude a procuring agency from purchasing wooden landscaping timbers and posts. They simply require that procuring agencies, when purchasing plastic landscaping timbers and posts, purchase these items made with recovered materials when the items meet applicable specifications and performance requirements.

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Product Specifications:

Plastic lumber cannot be tested using the same tests already developed for virgin plastic. Tests on virgin plastic are performed on small cross-sections of the material. This is an accurate indicator of how the virgin plastic will perform as it is a homogeneous material. Plastic lumber, however, is not homogeneous in its construction, so tests on a cross-section of this material do not accurately predict how a length of lumber will perform in certain circumstances. For this reason, new test methods have been developed for lengths of lumber. These test methods apply to all types of plastic lumber or equivalent materials that are not homogeneous at the cross-section. These test methods are as follows:

ASTM is working on draft test methods for shear properties.

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Product Information:

Database of Manufacturers and Suppliers
This database identifies manufacturers and suppliers of plastic lumber landscaping timbers and posts.

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Additional Links:

2007 Buy-Recycled Series: Landscaping Products (PDF) (7 pp, 120K, About PDF)
This fact sheet highlights landscaping products designated in the CPG, including plastic lumber landscaping timbers and posts, and includes case studies, recommended recovered-content levels, and a list of resources.

Technical Background Document (PDF) (215 pp, 381K, About PDF)
This background document includes EPA's product research on landscaping timbers and posts, as well as a more detailed overview of the history and regulatory requirements of the CPG process.

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