Does the Marble Test Really Work?
But can rolling a marble test really reveal if a home has this kind of a problem?
The marble is a good way to demonstrate the floor is not level, but not to tell if this means there is a problem.
Instead, there’s a different tool you’ll need. Put a 4-foot-long level on the floor. Ideally, when the level is level, the end should not be more than an eighth of an inch off the floor. If it’s a quarter inch or more, the house should be checked.
An uneven floor could indicate a structural problem or possibly poor workmanship.
The truth is, all floors are going to be a little bit unlevel. If you can notice your building dipping, that’s not acceptable. Between one room and another, if a marble rolls, you’ll survive. After all, a marble could roll from room to room because of different finishes on the floor.
The real value and importance of having a professional inspector or structural engineer inspection is that they can tell you whether the settling is active (i.e., worsening) or cosmetic (i.e., not structural, but a function of the age of the building).