For the longest-lasting exterior paint, consider acrylic or enamel (oil-based) paints. Acrylic paints, including acrylic latex and acrylic enamel, are known for withstanding harsh weather and sun exposure. Enamel-based paints are also one of the most durable options available. While latex paint is common, it typically has a shorter lifespan than acrylic or oil-based options. The paint's finish also affects its durability; a higher gloss finish is generally more durable. For resistance to moisture and cracking, matte and satin finishes can be effective, while a high-gloss acrylic or oil-based paint offers a combination of maximum longevity and durability.

Staining or sealing a cedar deck or fence is highly recommended to extend its lifespan and protect it from the elements. While cedar is naturally resistant to mold and mildew, it is not impervious to damage from moisture, sun exposure, splintering, fading, and rot over time. Applying a protective finish creates a shield that preserves the wood's strength and appearance, potentially extending its life by five to 10 years.

When choosing a finish, it's helpful to understand the difference between a sealer and a stain. A sealer sits on top of the wood, whereas a combination stain and sealer soaks into the top layer. Because it penetrates the wood, a stain generally offers better protection against UV damage and rot and lasts significantly longer. For the best results that also preserve the wood's natural color, consider using a near-translucent stain.

To maintain protection, plan on reapplying the stain or sealer every two to three years, either as a DIY project or by hiring a professional.

The best paint for an older deck depends on the material and whether or not your deck already has a coat of paint. Generally, if your deck already has paint on it, you should choose the same type of paint when repainting the deck. For example, if an old deck has oil-based paint on it, stick with oil; if your deck has water-based paint, choose water-based paint. 

Wet-sanding and dry-sanding each have pros and cons. Dry-sanding is less messy, so it’s a good option if you’re trying to minimize dust (for example, if you’re sanding an occupied home or working with particularly dry or dusty drywall mud). However, dry-sanding is quicker because you don’t have to keep rinsing a sponge or wait for it to dry before painting.