I have a new deck installed a year ago that is ready for stain. It is about 1000 sqft including steps, railing, accent beams, lattice, etc. Will 5 gallons of stain be enough?[/quote]
No. See this for help on the amount:
Should be closer to 10 gallons for two coats applied wet on wet.[/quote]
Per your help page and under [b]Staining New Wood and Decking for the First Time[/b], it advises to apply 1 coat for new wood. Is that no longer correct? "Even after the waiting period and the proper prepping, new smooth wood is still not as absorbent as it will be in a few years.[b]We strongly suggest only applying 1 coat of the TWP Stains the first time.[/b] Do not over apply as the TWP may not penetrate into the wood correctly..."
Your deck is a year old so it is really not "new" anymore. Either apply two light coats or one good coat is fine. If you do one coat, you will need about 7 gallons.