What you will notice
Sloping floors creep up slowly. Most people notice something else first:
A ball or marble rolls
It always rolls the same way in one room.
A dip in the middle
The floor sags toward the center of the house.
A tilt toward one wall
The whole floor leans toward one outside wall.
Bouncy or soft spots
The floor gives when you walk on it.
Gaps at the baseboard
Space opens between the floor and the trim.
Doors that swing on their own
Or doors that rub at the top on one side.
Cracks in plaster
Running from the corners of doors and windows.
Tile or grout cracking
In kitchens and baths above the low spot.