When Grams and Gramps were newlyweds they lived in a small flat above his law office in downtown Capeside. Grams tells Jen that they dreamed of owning one of the summer houses by the Creek and living in it year-round, which they eventually did.
The house has two stories, with three upstairs bedrooms. The downstairs has a kitchen/dining-room combined and presumably the bathrooms are located on this floor. It is possible a second bathroom is located upstairs. The front door opens out onto a porch with a view of the Creek.