A sagging, uneven, or springy floor can be the result of many different issues in a home. In fact, this kind of issue is often the result of a mix of underlying issues that all must be addressed to get a solid solution.
The whole structure of your property is reliant on every part of itself to ensure optimum support and stability. While some parts of a home are particularly important, like the foundation, for example, any serious structural damage in your home can feasibly lead to issues like sagging or uneven flooring. In fact, if the issues are left to grow unchecked, they could lead to the collapse of affected walls and floors. With that said, the issues most likely to cause sagging floors are issues in your property’s foundation.
Settlement, subsidence, and lateral movement can all cause sufficient damage to the supports and joists inside your crawl space and lead to a sagging or uneven floor. Each of these issues is most likely to be caused by problematic foundation soils. Expansive soils, for example, are very unstable and swell or shrink depending on their saturation. This can cause sinking or settlement. Weak or loose soils, by contrast, can be washed or blown away and cause settlement as a result of voids being formed under or around your home. Either way, foundation damage is a common cause of sagging flooring.
Rotted Floor Joists
A more localized cause of sagging flooring is some kind of damage to the joists that support your property’s flooring. Joists that cannot support the weight they were intended to are known as over spanned joists, and they can come about as a result of damage, decay, or poor design. Rotted floor joists fall into the category of decay or damage and are hard to deal with.
Joists that are failing as a result of rot will fail more slowly than those that are failing because of deep cracks or structural movement. This means you will have a little more time to act. You will first notice a slight spring or bounce in your flooring. This will develop into a defined sag and could eventually lead to the collapse of the floor as a whole.