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Synthetic decking installation (C) Daniel Friedman 2013Composite or Synthetic Deck Installation
Deck Design-Build Online Guide

Composite & synthetic decking choices, properties, & installation procedures.

The most common type of composite decking is made of wood fibers mixed with plastic, which is then formed into planks up to 20 feet in length.

Solid synthetic deck boards are sold in various thicknesses, widths, and lengths, of which 1" thick x 5.5" wide x lengths of 12', 16', and 20' are most common.

Some products are made to resemble real wood, at least from a distance, while others offer a range of colors.

This article series describes critical safe-construction details for decks and porches, including avoiding deck or porch collapse and unsafe deck stairs and railings. Our page top photo shows several colors of synthetic decking installed at a New York building supply outlet.

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Using Composite Decking: Synthetic or "Plastic" Deck Boards

Synthetic deck collapse (C) Daniel Friedman

Good decks are primarily built to promote leisure and comfort, but they can require a fair bit of upkeep to keep them looking good. Composite decking has been gaining in popularity in recent years because it significantly reduces the maintenance that a deck needs from year to year.

New products are being introduced all the time, though many of them are not available in all areas or carried by all stores. If you are curious about composite decking, plan to visit as many stores as possible and do some research on the specific products available to you.

The composite deck board photo at left shows that the deck actually collapsed during work on the structure, revealing rotted wood structure over which the deck boards had been added as a "repair".

Some manufacturers have begun offering composite lumber that can be used for railings and fascia boards, giving you the opportunity to construct the most visible portions of a deck out of the same material. You may also be able to use composite lumber for stair treads and risers.

Watch out: Composite lumber is generally not as strong as wood, which is why it is not used for structural framing. The strength of composite decking varies from product to product and installation.

Decking made with recycled polyethylene (PE) may require shorter spans than products made with poly- vinyl chloride (PVC), which itself may not be able to span quite as much as some solid wood decking.

Each product is made from a unique mix of materials, and some may fade more than others.

With a growing variety of products available and an expanding list of happy consumers, composite decking is rapidly becoming the material of choice for those seeking a low-maintenance deck. Because of its flexibility, it is also well suited to use in curved decks and even matching benches.

Watch out: synthetic decking is not a "forever" material and can deteriorate, break, even collapse as we illustrate in some photos here and as has been reported elsewhere.

Manufacturers typically cite a 25-30 year life expectancy though we've seen the material fail sooner, within 10-15 years.

Details are at COMPOSITE LUMBER DURABILITY

Cutting and Drilling Composite Deck Materials

Trex type deck boards at Home Depot store (C) Daniel FriedmanAlthough composite or synthetic decking itself is relatively recent, you do not to acquire new tools and skills to work with it. Composites can be cut and shaped just like solid wood.

Use regular carpentry tools to cut, drill, and shape composite lumber. Fine-toothed, carbide- tipped blades work best.

Cutting or drilling composite lumber may produce a sharp burr, which can be quickly eliminated with a rasp or sandpaper.

Staining and Painting Composite / Synthetic Deck Materials

Unlike wood, according to some sources, composite decking does not have to be coated with a protective finish. If you are not satisfied with the color choices available, however, or if you would like your deck to match the color of your house, most products can be stained or painted.

Keep in mind that if you do apply a finish, you will have to recoat the surface regularly. Some manufacturers suggest oil-based paints and stains for their products, while others recommend latex finishes.

Composite lumber does not necessarily have to be coated with a protected finish, but for decorative purposes you can stain or paint as suggested by the manufacturer.

Watch out: check the coating requirements or recommendations given by the manufacturer of the particular synthetic decking material you are choosing.

Fastening Requirements for Synthetic Decking, Trex, Plastic or Similar Products

Most composite decking can be attached with standard deck screws or nails. Some manufacturers suggest that you drill pilot holes before driving screws, others do not.

Vinyl Decking

Vinyl decking is another low cost option, although one that offers a particularly nontraditional-looking deck.  Installation differs as well.  In general, first an aluminum or vinyl track is installed across the joists, and then top pieces are snapped into place.

Note that in this immediate discussion, we have eschewed environmental and health questions concerning the use of treated wood, vinyl and other manmade products, as well as questions of renewable resources and environmental impact. Articles on those topics can be found at InspectApedia.com such as at

Sorting Synthetic Decking by Board Types: solid, webbed, other

Solid Composite Decking

Solid composite decking is the composite product most similar to solid wood and can be fastened accordingly. Hidden fastener systems can also be used with some products, but check with both the fastener and composite manufacturers for compatibility. Some solid composite boards may have a slight cup, which should be installed with the arch facing up ("rainbow position") to allow water to run off.

Webbed Decking

Figure 4-3: Hollow profile synthetic decking (C) J Wiley, S BlissWebbed, or hollow-core, composite decking is available in both rectangular and tongue-and-groove profiles. Because of the products’ design, manufacturers specify exactly where fasteners must be driven in each board.

Shown at left is a non-solid composite decking product. This image is used with permission from Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons) , by Steven Bliss, courtesy of Wiley & Sons.

Also see our review of that book.

In a companion article on this topic, SYNTHETIC & COMPOSITE DECK BOARDS - Best Construction Practice,

Mr. Bliss points out that the oldest solid composite decking on the market is Trex®, but competitors now include Boardwalk® (Certainteed), ChoiceDec® (Weyerhaeuser), and products from several smaller manufacturers

Some products are made with a surface groove to accommodate fasteners. You can buy matching caps to enclose board ends, or you can install fascia boards.

Attach composite decking with screws and nails, as recommended by the manufacturer. Some products tend to flare up a bit when the screw head enters the decking. If that happens, draft the screw about 1/8 inch beneath the surface, this step will hide the screw.

With webbed decking, fastener placement can be particularly important. This 2 X 6 product requires that screws be driven only through the outer cores, not the center one.

Where to Buy Composite & Plastic Decking Materials

Veranda composite decking warranty terms (C) InspectApedia

Building Supply Stores such as Home Depot & Lowes stock a variety of composite and synthetic decking products including those shown in the photographs above. At left is an image of the Veranda Composite Decking warranty.

Plastic Decking Systems



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