plastic_lumberIn a continuation of our series discussing innovative building materials, we will examine plastic lumber and how it may benefit the construction industry.  There are two types of plastic lumber products: the composite form that is a mixture of plastics and natural fibers and the wood-like form that is made solely of plastics.

Plastic Lumber Advantages

A study by the US Army Corp of Engineers confirmed that composite products are durable and resistant to weather, insects, rot and moisture. Unlike traditional lumber, plastic lumber products do not require the regular maintenance of repainting and restaining.  Plastic lumber may be a great alternative to wood when used for a deck or outdoor space.  The plastic products do not crack or splinter, eliminating the possibility of sun damage or a painful splinter in your foot.  Both types of plastic lumber can be formed using either new or recycled materials, decreasing some of the plastic disposed of in landfills.  The natural composite form is popular among German automotive manufactures.  Companies use on average 15-22 pounds of composite material per vehicle in nonstructural applications such as interior paneling, headliners, and seat panels.  One of the primary factors driving the increase use of plastic lumber is the rising number of ASTM International standards.  These new standards assist engineers in structure design.  The Plastic Lumber Trade Association (PLTA) developed many of the current standards.


Plastic Lumber Disadvantages

One of the primary disadvantages of plastic lumber is its reaction to the thermal environment.  The plastic product has an increased rate of thermal expansion and contraction when compared to traditional wood.[ii]  Do to this thermal property, plastic lumber is rarely recommended for interior residential projects.  Plastic lumber is not as strong as traditional wood, and special care must be taken when handling it on a construction site.  Plastic lumber also has a relatively low stiffness and flexural strength.  This could explain why plastic lumber is often used for decks or walking surfaces where flexibility is not as important.[i] One rare known safety concern associated with plastic lumber is its resistance to water when burning.  If plastic lumber catches on fire, water will only cause the fire to spread.  Carbon dioxide, dry chemicals, or foam must be used to extinguish the fire.[iii]

In an effort to help decrease the rising rates of deforestation, alternatives to traditional wood products have been on the rise.  When proper precautious and planning is taken, plastic lumber can be an economically and environmentally friendly alternative to traditional wood lumber.  With increased understanding of the product and and its performance abilities through standard tests, plastic lumber may see an increased level of usage in the construction industry.