Deck Maintenance - Composite Materials and Plastic Lumber

Wood is still the preferred decking material, but composites and plastic lumber are growing in popularity and now account for about 20% of the market. What are some of the features of these products, and how do you maintain decks made with them?

Deck Maintenance - Composite Materials and Plastic Lumber

Wood polymer composite is a mixture of wood by-products and recycled materials that are combined under pressure and exuded into boards. The result is a material that is designed to resist rot and insect damage, and also is said to be free of the problems that afflict wood decks, such as weathering, cracking or splitting.  There also is true plastic lumber that contains no wood and is composed primarily of recycled plastics and fiberglass. Wood is still the preferred decking material, but composites and plastic lumber are growing in popularity and now account for about 20% of the market. What are some of the features of these products, and how do you maintain decks made with them?

Strength

Unlike wood, composites cannot be used for structural components because they lack tensile strength, meaning that they bend easily. The warranty for a composite deck can range from 10 to 25 years, but a deck will last only as long as its weakest component, and the deck frame likely will fail before the decking does.  On the other hand, there now is a structurally rated plastic wood product.

Stains

Grease will stain composite material, so stains must be dealt with promptly per the manufacturer's instructions. Sometimes professional pressure-washing is needed, but the important thing is to use caution because too much pressure for too long on a given section will damage the quality of the surface. The claim is that plastic wood does not absorb water and does not stain.

Fading

Composite materials will fade over time, while it is said that plastic wood does not.

Mold and Mildew

These are common problems, meaning that both types of decks are not maintenance free. Keeping the gaps between boards clear of debris is the best prevention, along with periodic use of a deck cleaner to prevent buildup. It also is important that deck boards be properly spaced for drainage and airflow, usually not less than 3/16th of an inch.
Tannin Stains and Extractive Chemical Bleeding
All wood-based composites can experience these problems which occur when the chemicals in the product dissolve after extended contact with water. For extractive bleeding, follow the deck manufacturer's instructions as the components in these products can vary. Tannin stains will usually disappear after a period of weathering.

Environmental Issues

The case can be made that only natural wood is both biodegradable and sustainable. Composites and plastics are not.

Maintenance

Decks of composite materials and plastic wood are much lower maintenance than natural wood decks. Usually all you have to do is clean the deck once or twice a year with a deck cleaner and a bristle brush, scrubbing in the direction of the grain, followed by a rinse. Test the cleaner you plan to use on a small section of deck first to be sure it doesn't discolor or damage the surface. Products like paint, stain or sealers aren't needed, reducing costs and saving labor.

Some other precautions that are suggested for composite decks:

• Keep the deck clean and dry.
• Ensure adequate ventilation under and between decking boards.
• Don't let downspouts or dryer vents discharge directly on the deck.
• Clean your deck after a major pollen discharge.
• Avoid fertilizer and other chemical overspray.

Appearance

If you care about natural beauty, choose wood. Although composites have come a long way, they simply don't look like real wood, and neither does plastic wood.

Cost

Both materials are more costly than natural wood

Summary

Alternative decking materials are improving all the time and will claim more and more market share in the future. The right choice for your deck depends on your taste, budget and lifestyle.