what does the layout of the rooms suggest about Gregor's position in the family?

Gregor is the money earner in the family and is treated as simply that. His room is sandwiched between his parent's and sister's room, the living room in front of his. I always felt the irony here. Gregor was the centre of the family, financially. The position of his room reflects that, yet he remains isolated (when he gets all buggy)from his family while still being sandwiched in the middle.