How To Fix Sagging Floors


Have you ever set a marble or a pen on the floor and watched it roll away unexpectedly? This is not uncommon, as many homes shift as they age, resulting in sagging floors. Although a slight unevenness like this usually isn't much of a problem, uneven floors can be an indication of deeper structural problems. Don't wait for more costly damages to develop when you could make a few simple repairs to get them fixed.


Why Floors Sag

There are a few common reasons why floors don't remain level. One major concern is faulty design. Sometimes the floor joists simply can't support the weight of the floor above. This can happen due to a lack of support beams or even just poor math when the original architect was calculating the weight of overlying materials.

Sagging floors can be a result of poorly planned renovations as well, such as when support walls or important beams are removed to make way for modernized features. Another common problem is the shifts that come with aging. Any of these can be compounded by moisture, insect damage and fluctuations in heat. Fortunately, it's not usually difficult to identify the source of tipsy floors.


How To Inspect Sagging Floors

Knowing the common problems, there are three main areas you'll want to inspect when you suspect there is a problem with your floors.

  1. Support Beams: Any floor with a wood base, whether it be hardwood flooring or plywood with tile over the top, has support beams somewhere. The first place to check for damage is the joints of these beams. Examine the bases for water damage or cracking and observe where they meet walls or ceilings to see if there is any rot or splintering.

  2. Floor Joists: These are the boards that run horizontally under the floor itself. Once again, these can become rotten or cracked over time. A more common problem is that they have been improperly cut to make room for ducts, wiring or pipes, which can leave the whole floor unstable. Generally, no cuts should be made in the middle third of the joist, and even notching should not be deep.

  3. The Floor Surface: Although it can sometimes be hard to inspect joists and beams in houses without basements or with finished basements, anyone can take a look at the flooring itself. Peek under carpeting or examine the corners of the room to look for damage from insects and moisture.

There aren't very many reasons for sagging floors, so if you can't find any specific damage, the problem may be structural in nature. A level or even a marble can tell you where the slant is most prominent and therefore where to look for problems.


Ways To Fix a Sagging Floor

Many floors sink slowly over time, so repairs also need to take time to prevent cracks or stress. Depending on the kind of damage, you may be able to do floor repair with a system of jacks, but some repairs require more precise supplies. Start by installing jacks to raise the floor, making sure the jacks have solid footing. You might need to install footing pillars or other concrete supports to ensure the jack doesn't damage the surface below. Slowly jack up the floor over time and add supports as needed. Girders and sister joists can help with broken beams or can be used to hold up the floor while rotten or otherwise damaged wood is replaced.

Although repairs to sagging floors aren't usually complicated, they often take time. It might be wise to consult a professional to ensure this process is being done efficiently. Fewer mistakes mean more time to enjoy your level floor after the repairs are complete.