Older Houses often have weak foundations. To check for this problem get a laser level, a yard stick, and make some measurements around the wall. Your first step is to acquire a laser level that has an ability to self level as well as the ability to lock the leveling portion. After you get your level and yardstick, do the following
1) Set the laser level on the floor in its self leveling mode so that the laser shines a line on the walls that should be parallel to the floor. When the level settles down, you may find it helpful to lock the self-level. Note exactly where you place the level so that you can test some days or weeks later for additional settling.
2) Walk around the room and measure the height of the line on the yardstick. Make notes.
If your floor is perfectly level, then your lines should always be at the same point on the yard stick. If your floor is not settling, then these values will not change over a period of weeks or years.
If you are seeing settling, call us and we will help determine a good solution.