Start with the former, unlock the latter at 80 dwellers.

Water treatment plant / Water purification plant – Creates and stores potable water.Start with the former, unlock the latter at 70 dwellers. Diner / Garden – Produces and stores food.Start with the former, unlock the latter at 60 dwellers. Power generator / Nuclear reactor – Makes and stores power.Note that power, water, and food can only be capped at your max facility’s storage limit, so building an extra square or two of these can increase your storage capacity, preventing service disruptions. Production rooms – Necessary resources for the vault’s survival. Storage room – Just increases your inventory.Living room – The amount of living room space you have determines your maximum dweller capacity, even though dwellers will rarely spend time here.Overseer’s office – An unoccupied room which serves as your mission control room for quests.You will want two elevator shafts eventually as your vault builds up, to provide maximum mobility. Elevator – Chained together to make elevator shafts.Staff your two most butch fighters with their best weapons here to guard against invading raiders. Vault door – You get exactly one, always on the top floor at ground level.Utility rooms – Required for vault function. Rooms can be categorized by function, thusly:

Most rooms can be expanded to 3 sections wide and later upgraded. Be careful not to overbuild, because rooms left empty tend to attract disasters. Over time you will need a good balance of rooms to provide stable function levels.

The rooms are what your vault is made of, so plan them carefully.

Ideal fallout shelter layout