Possible causes for humps in the floor

Q: We lived in our home for 22 years and recently noticed a hump in a floor between the kitchen and the living room. The home has a basement where we can see the floors, and I cannot see anything like a hump. We never noticed this until the carpet was removed and a new wood floor installed. Do you think this was always there and unnoticed?

A: A hump may appear during construction, or it could take several years to develop. Without knowing the layout of your home, I will tell you what I have seen in a standard ranch-style home with a kitchen at the rear corner of the home and a living or family room at the front corner of the home.

There is usually a hall from the kitchen/living room areas that leads to the bathroom and bedrooms. In the basement a beam made of steel or wood extends from the kitchen to the bedroom. Floor joists usually extend from the front of the home to the back and overlap one another at the beam. When a floor joist or joists are too long and extend past the center beam, they can cause a hump in the floor.

A wood floor joist will deflect or sag near the center of the joist under the weight of the flooring and furniture. When a joist sags, the end that is past the center beam will push up in an action similar to a teeter-totter. It’s the end of the joist being pushed up that causes the hump.

The kitchen has heavy cabinets, appliances and furniture. The concentrated weight pushing down on the floor joists that are too long often leads to a humped floor in the room next to the kitchen.

A floor joist should overlap the joist next to it by only three to four inches. The hump may be noticeable, but unless it is causing cracks to the rooms walls and/or ceilings it is not a major problem. You can have the joist or joists cut off where they extend too far past the beam. The defect may disappear over time.