The basement is a large room.
It has a washing machine and a dryer, along with a workbench. In "The Slumber Party," there is a basement shown as a root beer cellar. In "Barnacle Face," the basement is a dungeon-like place where Mr. Krabs makes his soap out of Krabby Patties.
On the first floor is the living room and there are many valuable items, such as pictures, a vending machine, a doll-a-rama, and knick-knacks. By the front door is a barrel TV. The kitchen and dining room are all in one room. In the dining room, there is a table, chair, and a window with a curtain. The second floor to the right side of the house contains Mr. Krabs' bedroom.
He sleeps in a hammock and has a bedside shelf. A bathroom is connected from the bedroom, which includes a toilet and a sink with a mirror. Pearl's bedroom is located on the left side of the house and contains a bed and walls filled with Boys Who Cry posters, as she is a huge fan of the band.
There is another floor in the center of the house in "Barnacle Face." On this floor, there is the master bathroom. The bathroom contains a toilet and a sink.
There is a balcony on the top of the house.
Root beer cellar
Mr. Krabs has a root beer cellar underneath his house, which appears in "The Slumber Party."
In the episode, Mr. Krabs tells Pearl and her friends not to touch it, although SpongeBob empties all of his root beer. It then floods the house and ruins Mr. Krabs' house and his pile of old newspapers.
Pearl and her friends think SpongeBob is a monster after he absorbs all of the root beer in the cellar.
"Dying for Pie" - It was presumably destroyed with the rest of Bikini Bottom in an explosion.
"The Krusty Plate" - It was presumably destroyed with the rest of Bikini Bottom when SpongeBob used a maximum power laser to clean the plate.