What is the difference between composite and PVC decking, and which is better for San Diego?
Short answer
Composite decking has a core of wood fiber and plastic, usually wrapped in a protective polymer cap. PVC decking is all plastic with no wood fiber at all. PVC is lighter, more stain- and moisture-proof and often cooler to the touch, which helps on a sunny San Diego deck; composite tends to feel more solid, look more like wood and be more widely available. Both beat uncapped first-generation composite by a wide margin. Pick by heat, color and how the board feels, then follow the manufacturer's framing guide.
What each one is made of
Composite decking mixes wood flour with polyethylene or polypropylene and extrudes it into a board. Early versions were just that core, and they stained, grew mildew in the wood fiber and faded unevenly. Nearly every composite sold today is capped: the core is co-extruded with a dense polymer shell on three or four sides that keeps water and stains out and holds the color. The wood fiber inside gives the board stiffness and a convincing weight.
PVC decking, sometimes called cellular PVC, has no wood at all. It is a foamed plastic core with a hard cap, so there is nothing organic to absorb water or feed mildew, even at the cut ends. It is lighter than composite, which crews appreciate, and it can be heat-formed into curves.
Heat, which matters more here than most places
Any synthetic board gets hotter in full sun than wood of the same color, and South- and west-facing decks in Carlsbad, Vista and Escondido get a lot of full sun. PVC boards generally run a little cooler than composite because they carry less mass and some lines are engineered with heat-reflective caps. The bigger lever, though, is color: a light gray or tan board of either type is noticeably cooler than a dark brown one.
If barefoot comfort at 3 p.m. is a priority, choose a light color, plan shade over the lounge zone, and ask us to leave a sample in your yard for an afternoon so you can test it with your own feet. Marketing claims about cool boards vary; a sample does not lie.
Stains, scratches and repairs
Both capped composite and PVC resist food and wine stains well if cleaned reasonably soon. PVC has the edge on anything that reaches a cut end or a fastener hole, since there is no fiber to wick moisture. Scratches show on both; neither can be sanded. Deep gouges mean replacing a board, which is one reason we keep a few spare boards from every job for the owner.
Mildew can still grow on the surface of either in a damp shaded corner, feeding on pollen and dust rather than the board itself. It washes off with soap and a soft brush.
Framing and installation differences
Neither material spans like wood. Most manufacturers call for joists at 16 inches on center for boards run perpendicular to the joists, 12 inches for diagonal patterns, and tighter spacing again for stair treads; a few PVC lines allow a little more. Both expand and contract with temperature rather than moisture, so end gaps depend on the temperature on installation day and the manufacturer's table, and both are usually installed with hidden clips in a grooved edge.
PVC moves more with heat than composite, so long runs need careful attention to end gaps and to the breaker boards that divide a deck into shorter runs. On the composite deck and pergola we built in North County, we ran the joists tighter than the manufacturer's minimum so the boards would feel as solid as wood underfoot; that is a choice we make on most synthetic decks.
Which one we would choose
For a shaded or partly shaded deck where appearance and a solid feel matter most, a good capped composite in a mid or light tone is hard to beat and comes in the widest range of looks. For a fully exposed deck, a rooftop or a surface near a pool where heat and standing water are the daily reality, PVC in a light color is the safer bet. In either case, the warranty and the local availability of matching boards years from now are worth as much as the spec sheet.
Related questions
Does PVC decking look fake?
The better lines now carry multi-tone streaking and embossed grain that read as wood from a few feet away. Up close, PVC tends to look more uniform than composite. Looking at a full board in daylight, not a two-inch sample, is the only way to judge.
Is composite decking slippery when wet?
Capped boards are generally comparable to wood when wet, and most carry a slip-resistance rating. Smooth, heavily embossed or algae-covered surfaces are the slick ones. Keeping a shaded deck clean matters more than the material.
Can composite or PVC decking be used in a fire hazard zone?
Some products are tested and listed to the ignition-resistance standards California requires for decking in designated fire hazard zones and many are not. We check the specific product's listing against your address before ordering.