Pros, Cons, and Eco-friendliness of Composite Decking
Adding a deck to your home can be a real asset in terms of enjoyment now and future re-sell value later. Planning the design and choosing materials is a different experience for every homeowner -- making your deck truly unique. If you’re considering synthetic decking instead of traditional wood decking but you’re not 100% sure if it’s the best choice for you and the environment, then I hope my research can shed some light.
Ingredients
Composite decking is made from wood waste and recycled plastic. The composites are made from one of many polymers, the 3 most common are: polyethylene, polyvinyl chloride (PVC), and polypropylene. There is also a finely ground wood flour and additives that stabilize the plastic as well as protect it from UV damage.
Polyethylene decking composites make up the biggest share of the composite decks market. This is the stuff that plastic bags are made with. It is comprised of wood fiber and plastic and is the most wood-like of the synthetic materials.
Performance
I’d like to tell you that you can compare apples to apples when comparing product but it’s just not the case in synthetic decking – all the manufacturers have their own secret concoction and, depending on what their recipe is, will determine the deck’s performance.
How it performs depends on what type of plastic is used, the types of additives and stabilizers, the proportion of wood flour to plastic in the mix, how it’s made, and how it’s installed. Some manufacturers use all recycled plastics in their decking, making it more eco-friendly, some use more wood flour than others. Wood flour, by the way, gives it the wood grain appearance but makes the plastic weaker, and in some decking, wood flour is the only recycled product with no recycled plastic.
All-Plastic
Polyethylene is a material used to make all-plastic decking and it’s usually recycled material. The upside is there’s no color fading or water/stain absorption. The downside is that some have a shiny appearance because there aren’t any wood particles in the recipe, and thermal expansion has been a big problem.
Other types of all-plastic decking include: PVC, polystyrene, and cellular PVC. All are prone to thermal expansion and less likely to stain.
Pros of synthetic decking
- Saves trees
- Helps keep discarded plastic out of the landfills
- Low maintenance
- Won’t crack or split
- Environmentally friendly – some materials include post-consumer recycled content
Cons of synthetic decking
- Mold & mildew
- The acidic chemicals used to clean the mold off the decks leave a powdery residue and strip the finish. The cleaning products can splash onto plants.
- Color fades.
- Cost is 2 – 5 times more expensive then pressure treated lumber.
- Requires smaller joist spacing.
- Thermal expansion can cause boards to shear screws and joints that don’t line up.
- PVC produces dangerous by-products and releases dangerous toxins when burned.
- Some plastics used are difficult to recycle at the end of their service life.
- Difficulty removing sap, grease, and other stains.
For more information on the green aspects of synthetic decking, I highly recommend The Healthy Building Network’s article titled “Guide to Plastic Lumber,” published in 2005 and based on a survey of manufacturers.
Resources:
- Professional Deck Builder Online - Wood subsititutes cost more but promise less maintenance
- Composite Decking vs. Wood Deck
Questions and Answers
| Answers | Original Poster | |
|---|---|---|
| Cleaners for Composite Decking | 0 |