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.

You’ll need to wait until the surface is completely dry, which can take anywhere from 24 to 48 hours under optimal conditions. The waiting period depends on several factors, including the type of siding and the weather conditions. Trying to paint before the surface is completely dry can trap moisture under the paint, leading to bubbling, blistering, and mold growth.

Yes, you must thoroughly clean your deck before staining. If you don't, dirt, debris, grease, and mildew can get trapped between the wood and the new stain. This not only looks unsightly but also prevents the stain from penetrating the wood properly, reducing its ability to protect the deck from weather and UV rays. As a result, the stain won't last as long or look as good. Any existing mold or mildew left untreated can continue to grow beneath the new stain, potentially leading to wood rot and structural damage. Always wait at least 48 hours after cleaning for the wood to dry completely before applying stain.

In most cases, sanding an old deck before staining it is necessary to achieve a decent finish. If your old deck has a relatively new stain finish on it and you're only doing touch-ups, you can generally skip the sanding part. However, if your goal is to make the deck look and function better, sanding first is a must.