Next to 100% synthetic materials or aluminum, no widely sold decking comes so low-maintenance as to be nearly “no-maintenance” as composite lumber. That’s one of the biggest reasons it has so effectively unseated pressure-treated lumber as the quintessential budget-minded material for new decks nationwide. Its makeup is comprised of a great enough proportion wood and cellulose fibers to lend it all the attractive qualities of a natural wood. Meanwhile, its synthetic components, usually plastic or polyurethane, protect it soundly from the pests, rot, fungus, mold and elemental battering that speeds natural wood’s deterioration.
Composites are durable, tough and manufacturers the world over have gone one extra mile after another to make them often comparably attractive to natural woods, but there’s one claim that comes under some embellishment: the color of composite decking is not exactly “permanent” as professed. Like many other materials, it eventually fades and will incur some degree of mildew.
Staining to either preserve composite decking’s factory color or even change it entirely is possible, but there’s a very well-defined “right” way to go about it for the most appreciable results.
Whatever your color-changing plan of attack may be, whether you mean to stain or paint, you’ll likely need to first perform some mildew removal. Composite decks aren’t the nutrient buffets that many natural-wood structures end up being, but given that composites are partially organic, you’ll need to start with a one-part-bleach to three-parts-water solution liberally applied to the deck’s surface, steps, railings and/or benches. After letting it set in for 20 minutes, scrub all surfaces down with a long-handled brush and finish by rinsing any mildew residue away with the solution itself.
You’ll sand the surface next with a #220 very fine sandpaper to remove the composite’s gloss – if working with a textured composite, then sanding with the wood grain. The last cleaning step is to apply a household detergent solution or specially formulated commercial cleaner to remove the composite decking’s dirt and dust completely, once more finishing with a thorough rinse.
If applying a deck stain, you’ll want to skip the priming stage. If you’ve chosen to paint, we recommend an exterior latex stain-blocking primer for any plastic material. Before beginning the actual painting or staining, know that you’ll be revisiting this process roughly every three to five years from now on to keep up with the elemental and foot-traffic pounding a face-up exposure takes constantly. No paint or stain is invincible.
Finally, apply a semi-gloss or satin finish of latex floor and deck paint. We suggest opting for the upgraded mildew resistance and easier cleaning that comes with a higher-gloss paint. If staining is more your speed, go with a formula tailored specifically for composite decking, usually an acrylic latex solid color deck stain.
As you revisit these steps, remember to stick with avoid oil-based products if you’ve already opted for an exterior latex coat previously. When combined, cracking oil coatings can quickly soil your deck’s appearance.