Environmental Factors

• Wood is a natural and renewable resource. Thus, it is preferable over plastic for those who are concerned about their impact on the environment. Due to this trend in more green-friendly materials, some companies are now offering molding made out of recycled plastic.
  
  

Moisture

• Plastic molding is non-porous and will not absorb water. This makes it a good option for homes in humid climates that have mold issues. It is also useful in bathrooms and laundry rooms as these areas are more prone to mold growth. Wood is porous and more susceptible to mold growth, as well as warping and shrinkage.
  
  

Installation

• Wood molding is easy to install as you can drive nails directly into the wood whereas you need to drill pilot holes in plastic molding. Some types of plastic molding feature adhesive backing and do not require nails or screws. Another consideration is that plastic is not as flexible as wood. If your walls are not perfectly straight and the corners not perfect right angles, the plastic will not bend into the walls as it would with wood molding.
  
  

Cost and Design

• Plastic molding is generally cheaper than wood molding. Wood molding has the added expense of primer and paint while many types of plastic molding don't require painting. In terms of design elements, plastic crown molding can offer more intricate features than wood molding. This is because the manufacturing process involves injection-molding rather than carving.