A foundation is a buildable structure in Stranded Deep. Foundations act as the base for a player's structural builds; without a foundation, the player will not be able to build a stable shelter. Building a foundation requires either Wood Sticks, Plank Scrap, Clay Bricks, or Corrugated Scrap. Once a foundation is set, the player will then be able to attach any sort of extension or addition, including Walls, to expand or fortify their shelter. Players will also be able to place any items in their backpack onto a foundation to keep them in a safe area.
- Players are able to make practical use of the foundation by setting it up as a makeshift 'barbeque grill'. This can be done by placing a foundation over a lit campfire before dropping food items onto it - the foundation will suspend the food over the fire, while fire burning through the foundation will cook it.