Most experts say, stick with stain. The problem with paint is that most deck surfaces are horizontal so the paint just lays on the deck. As a result, those areas hold water. Expert John Nearon says, "As the wood shrinks and expands with changes in moisture and temperature, the paint doesn't always have the ability to move at the exact same rate and the only thing it can do at that point is release and let go of the wood and that manifests itself in cracking and peeling and chipping of the coating."
Deck staining may seem like a simple weekend DIY project, but it's a time-consuming job. If you don't have the time to commit or the expertise to do proper prep work like power washing, a pro can help you get the longest-lasting results. Angie Hicks with Angie's List says, "Typically a company will quote staining a deck by the square foot or by the hour, so be sure it's clear in the estimate, the size of the deck. Additionally, find out what types of materials they are going to use and remember if they are going to have to do a lot of prep work, like stripping old paint or stain, that's going to cost extra."
Wood decks need to be re-stained every few years because even the best stains will fade, especially in high traffic areas.