What's In This Stuff? Not all composites and PVC decking and trim are alike. Here's why–and how to pick the best products for your store.

Intentionally Vague

Manufacturers of wood-plastic composite (WPC) and polyvinyl chloride (PVC) products closely guard their recipes for making their goods, even when they list in Material Safety Data Sheets the ingredients they use. Actually, exact percentages would be near impossible to declare because variations in core products and in the working environment can make it necessary to adjust the recipe nearly every day. But based on the collective responses, it's a safe bet all use PVC or polyethylene, various additives, and–in the case of WPCs–wood or some other form of cellulose.
Source: Companies' Material Safety Data Sheets

Manufacturer / Brand name(s) / Product type / What Is It? / Composition by weight

A.E.R.T. / ChoiceDek, MoistureShield / Decking / WPC / 45%-48% polyolefin, 49%-52% red oak fiber, 0.01%-1.5% carbon black (for products with colors), 1% to 5% metallic oxide pigments (for products with colors).

Advanced TrimWright / ATW Trimboard / Trim / PVC / 50%-100% PVC, zero-50% proprietary mixtures.

Aeratis / Aeratis / Porch / PVC / 50%-85% PVC compound, 10%-25% cellulose, zero to 5% lubricant mixture (calcium stearate, paraffin wax, polyethylene wax), zero to 3% process aids, acrylic polymers (proprietary), zero to 10% impact modifiers, acrylic (proprietary), unlisted amount of colorants (titanium dioxide and proprietary organic and inorganic pigments).

AZEK (Vycom Corp.) / PVC, Vintec I, Vintec II, Celtec, AZEK / Trim / PVC / 70%-95% PVC polymer, zero to 30% calcium carbonate and titanium dioxide, zero to 2% heat stabilizer (organotin compounds), zero to 4% lubricants (calcium stearate, paraffin, polyethylene, polyamide compounds, or esters); zero to 2% process aids (acrylic compounds), zero to 10% impact modifiers (CPE, ABS, MBS or acrylic compounds), zero to 2% organic and inorganic colorants, zero to 1% blowing agents (azo compounds or sodium bicarbonate).

Barrette / Barrette Outdoor Living / Railing, fencing and sheds / PVC / "All ingredients are bound up in the manufacturing process and are not expected to create any hazard in handling or use. Finished goods are inert."

Deceuninck North America / Composite wood product / Decking / WPC / 55%-90% wood flour, 5%-35% high-density polyethylene, <10% inert proprietary ingredients, >5% talc.

Deceuninck North America / PVC compound / Decking / PVC / >30% PVC resin, <5% organotin stabilizer, <70% mixture of proprietary additives.

Fiber Composites LLC / CertainTeed EverNew PT / Decking / WPC / "This matrix contains predominantly wood fiber and polyethylene. The polyethylene can be sourced as virgin or regrind (recycled) materials. The standard product is approximately 50% thermoplastic and 50% wood fiber."

Fiberon / Fiberon decking including Home Select; Horizon and Pro-Tect decking / Decking / WPC / 40%-60% wood fiber, 60%-40% polyethylene.

Fiberon / Horizon Plus / Guardrail / WPC / "This mixture contains predomantly wood fiber and PVC. The PVC can be sourced as virgin or regrind (recycled) materials). The standard product is approximately 75%-90% thermoplastic and 10%-25% wood fiber. In addition, the extruded profile (guardrail components) are covered in a predominately PVC capstock."

Fiberon / Outdoor Flooring / Decking / PVC / 75%-99% PVC resins, zero to 20% calcium carbonate, zero to 12% titanium dioxide, zero to 10% impact modifier, zero to 7% wax, zero to 5% processing aid, zero to 2% calcium stearate, zero to 2% tin stabilizer, zero to 0.5% pigment.

Formosa Plastics Corp. / CertainTeed EverNew LT / Decking / PVC / 75%-99% PVC resins, zero to 20% calcium carbonate, zero to 12% titanium dioxide, zero to 10% impact modifier, zero to 7% wax, zero to 5% "processing aid," zero to 2% calcium stearate, zero to 2% tin stabilizer, zero to 0.5% pigment.

GAF / DuraLife Natural Grain Collection / Decking / High-density polyethylene/rice hull / 40%-60% rice hulls, 25%-50% polyethylene, 10%-35% proprietary non-hazardous materials.

GAF / DuraLife Porch Collection / Porch / WPC / Zero to 70% sawdust, 25%-50% polypropylene, 15%-35% talc, 1%-5% zinc stearate, 10%-35% proprietary non-hazardous materials.

GAF / DuraLife RailWays / Railing / PVC/rice hull / 40%-60% rice hulls, 40%-60% PVC, zero to 5% calcium stearate, zero to 5% carbon black, zero to 5% calcium carbonate, zero to 5% titanium dioxide, zero to 5% crystalline silica, zero to 5% amorphous silica.

GAF / Duralife Siesta / Decking / Composite with wood or rice hulls / Zero to 70% sawdust or rice hulls, 25%-50% polypropylene, 15%-35% talc,10%-35% proprietary materials.

Guardian / Guardeck Elite / Decking / PVC / 50%-100% PVC, zero to 50% proprietary.

Guardian / Guardeck Prestige / Decking / WPC / 50%-65% wood flour, 30%-50% recycled high-density polyethylene flake, 1%-4% coloring agents, 1%-5% polyethylene homopolymer, zero to 8% proprietary mixture.

Inteplast Group / Tuf board products, Veranda HP, CEVN decking, InteFoam, InteCel, InteCel PW / Decking, trim, railing, fencing, molding, millwork / PVC / 50%-100% PVC, zero to 50% "proprietary."

Kleer / Kleer Decking / Trim and molding / PVC / >70% PVC, <20% calcium carbonate, <15% titanium dioxide, <9% proprietary.

Natures Composites / TerraDeck / Decking / Polyethylene/wheat straw / 60% wheat straw, 30%-40% polyethylene,<5% proprietary.

Rhino / Master Rhino Deck / Decking / WPC / 30%-50% virgin high-density polyethylene, 50%-65% wood flour, 1%-4% colorant, 1% to 4% UV treatment (carbon black and titanium dioxide), zero to 8% proprietary mixture.

Tamko / EverGrain / Decking / WPC / 40%-60% polyethylene, 40%-60% wood fiber dust, zero to 5% coloring agent.

TimberTech / CX-9 / Decking / WPC / 40%-60% wood fiber dust, 25%-60% HDPE, 5%-20% "trade secret," and another 2%-10% "trade secret."

TimberTech / XLM / Decking / PVC / 65%-90% PVC, 3%-15% inert fillers (calcium carbonate, titanium dioxide), 1%-5% proprietary heat stabilizers, 1%-5% proprietary lubricants, 1%-5% proprietary process aids, 2%-10% proprietary impact modifiers, 0.1%-7% proprietary pigments.

Trex / Accents / Decking / WPC / "Plastic obtained primarily from reclaimed/recycled grocery bags and stretch film; wood fiber is typically obtained from furniture makers and/or waste pallets. Standard product is approximately 30%-60% thermoplastic and 30%-60% wood fiber."

Trex / Escapes / Decking / PVC / <90% PVC, <10% acrylic copolymers, <7% calcium carbonate, <7% glass fiber, <4% calcium stearate, <3% paraffin wax, <12% titanium dioxide, <2% organotin (SN) complex, <4% brown pigment (titanium, chromium, antinomy), <2% organic calcium compound, <2% chromium compound, <4% brown pigment (Cr, Sb, MN) compound, <10% talc.

Trex / Wood-polymer products, including Transcend / Decking / WPC / "Plastic obtained primarily from reclaimed/recycled grocery bags and stretch film; wood fiber is typically obtained from furniture makers and/or waste pallets. Standard product is approximately 40%-50% thermoplastic and 50%-60% wood fiber."

Universal Forest Products / Latitudes (listed in MSDS as "Extruded Wood Plastic Composite Products" / Decking and railing / WPC / 50%-75% wood flour, 25%-50% high-density polyethylene, <10% talc, <10% inert proprietary ingredients.

Versatex (Wolfpac Technologies) / Versatex Trimboard / Trim / PVC / >70% PVC, <10% calcium carbonate, <20% titanium dioxide, <20% proprietary additives.

Wolf / Wolf PVC Trim / Trim / PVC / 50%-100% PVC, zero to 50% proprietary mixture.