Do I paint or impermeable my deck first? My grandmother had a tentative deck built about 4 years ago,...

My grandmother had a tentative deck built about 4 years ago, however, I never get around to staining/painting the deck. Do I need to paint her deck first or impermeable it first or do they make a rainproof paint for decks?
Answers:    respectively is a different way to cover the deck..u can power clean up the deck and when its dry and u want to keep the wood looking raw then u are going to stamp the deck with some brand of hose down sealer.staining gets inside the wood and does not skin like a paint would, that path sealing it..fine art just covers the surface seal it that way
You do one or the other...not both. The paint would preserve the waterproofing from soaking in and the waterproofing would do like for the paint.