Wood Plastic Composites Poised for Growth in Window & Door Market

Manufacturers and extruders are exploring new framing alternatives
By Ross DeMeritt, Window Choice Co. Inc.
May 15, 2010
FEATURE ARTICLE | Materials & Components
Ultimate Pushout Casement
WPC profile extruders continue to expand their capabilities as far as shapes and finish options.

Today, many manufacturers see an opportunity to break out from the pack through the use of new
high-performance framing materials. Wood plastic composites, or WPCs, are an alternative ready for another look.

There are many different wood plastic composites, but most existing WPC formulations involve PVC and wood flour or fiber. Such products have long been viewed as having potential advantages over the traditional PVC, aluminum, and/or clad wood used in most windows and doors. This new material class, however, is poised for a major breakout because of five emerging trends:

  • Loss of exclusive patent rights for Andersen Corp.
  • Greening of the building products industry
  • Evolution of WPC extrusion die technology
  • Desire for product differentiation
  • Desire to have light commercial or residential products with lower U values.

Current applications
WPCs are already well established in the window and door market. Andersen has offered its Renewal replacement window line for more than a decade. Most believe that this product line generates very high gross margins. Andersen continues to push its dominance with the recent introduction of a builder-grade line in WPC, the 100 Series, which the manufacturer now offers out West.

One can look at the entry door market to see another example. Plastpro Inc. has been offering its PF series maintenance free doorjamb system for more than two years. Using available downstream die techniques, this company has solved one of the more demanding applications for paintable/stainable “no-rot” framing in the fenestration market. The fiberglass door maker has successfully developed a field paintable/stainable, entry door frame that can withstand the rigors of an application where ordinary rigid PVC would not suitable. Plastpro is using this optional doorjamb to give them a foot in the door to its competition’s customers. It can be painted or stained with ordinary household paints and the aesthetics match a high quality fiberglass door skin finish.

Another WPC fenestration example is the Crown Super-Room. Here, a forward-thinking company has
leapfrogged its competition by using WPC shapes to frame a patio enclosure/sunroom system. It requires no metal reinforcing for standard room layouts, avoiding the cost and thermal penalty of trying to “sleeve” metal frame cross-sections into more thermally efficient PVC profiles.

Andersen’s patents on WPC technology in the fenestration industry, however, have had a limiting effect on product research, development and applications at other window and door companies. Those companies interested in alternative framing materials for windows, therefore, should become aware of a 2007 court decision which limits the Andersen patents. It is wise to get an opinion from legal counsel, but a large WPC extruder successfully won the right to continue to produce structural WPCs as long as certain common extrusion methods were used.

Without breaking confidentiality agreements, my company can report that WPC windows are being designed and that companies are seeking qualified extruders at this present time. WPC extruders serving the fence, deck and rail (FDR) market are also looking at the window and door market as a new opportunity.

Finish Choices
The technology has also been evolving. A look at recent fence, deck and rail product introductions reveals many advancements that have been made in co-extruded and capstocked structural WPC profiles. Extruders have implemented numerous changes to improve the structural and cost properties of WPC products, and, over time, the cross sections have started looking more and more like window and door profiles, that is, multiple hollows and thinner walls with an aesthetic capstock finish layer. The bottom line is that there are more and more extruders of WPCs which are technically qualified to do WPC window and door profiles.

Paintable/stainable WPC profiles can provide realistic woodgrain options.

The technology to create a paintable/stainable interior with capstocked exterior window framing is available now. This framing would come out of the extrusion die with the exact shape needed, with the look of real wood (and fully paintable/stainable) on the interior, and with a maintenance-free exterior, including dark color options. Turn a switch on the extruder and the interior could be capped with an opaque color (same or different from the exterior) or a realistic faux pre-stained woodgrain requiring no additional finish.

One need only look at developments in the entry door market to see what’s possible. Faux woodgrain finishes on fiberglass doors have changed this market forever. Fiberglass door skins are readily field paintable/stainable, require little or no maintenance, and look better every day. With the right WPC profile extruder, equivalent technology can be used for window framing. With the right product design, WPC windows can take market share from other materials just as fiberglass doors have taken
share from steel doors.

Whatever one thinks about the green building movement, it is likely to be very influential in determining the performance characteristics that will be demanded in next generation of framing materials. There are reasons to believe WPCs will be well suited to meet those demands also. WPCs can be used for mechanically fastened or welded frames and can be used in wall thicknesses ranging from “builder’s grade” to premium commercial—in designs offering U-values of .20 and lower. WPC profiles can offer higher strength than rigid or cellular PVC products of similar wall thickness, lessening the need for conduction robbing metal reinforcement. Some extruders are able to add with cross-fed reinforcement strands to give even higher flexural strength. WPCs also eliminate airborne fiber issues associated with sawing or sanding pultruded products, either at the production plant or later in the field.

Continued technological development is also promising. When the recycling stream of consumer thermoplastics is combined with bonding agents already being developed, then coated with a thin layer of virgin capstock, the potential result is very low feedstock costs. A Web site, www.woodutilizaton.org, reviews recent research activities at 10 universities that have received millions in Federal grants to find new ways to use recycled resins from post-consumer waste. Bonding agents are becoming much more versatile, enabling different types of resin to be used without being separated as completely or cleanly as they have been.

Wood plastic composites can provide a new, improved option over traditional framing materials, as well as other new alternatives, such as fiberglass, because of their green characteristics, cost, strength and surface finish options. WPCs have the potential to deliver the strength of fiberglass, the extrudability of traditional PVC, thermal dimensional stability, low coefficients of expansion/contraction, with all the aesthetic finish options of real wood.

Ross DeMeritt is president of Window Choice Co. Inc., with offices in Sautee, Ga., and Mackinaw City, Mich. Founded in 1988, the company works with window and door fabricators to develop product concepts and matches fabricators with extruders using the latest in technology for high-margin fenestration products. He can be reached at ross@worldwidewindowdesign.com or 800/735-5782. This article originally appeared on WindowandDoor.com in January, but was updated and expanded for use in our May 2010 issue.