Does the couch look a little crooked? Are there gaps under your baseboards? Are the bedroom or bathroom doors sticking? Are there drywall cracks above the doors? Wait – is it time for new glasses already?  Before you get out the level or get your eyes checked, look down.  Sloping floors, caused by sagging floor joists, are a common problem, especially if you live in an older home. In most cases, sagging floor joists are treatable, if you act quickly.  When you notice your floor has started to sag, you should cautiously inspect for possible causes or hire a professional to take a look.  Minor damage now can quickly become major damage later, if left untreated.  A sagging floor caused by sagging floor joists can be an easily-fixable problem, or it can be a symptom of a larger issue, so it’s important not to ignore the warning signs.

Floor joists are used to support the floor of a home across an open area.  Floor joists are not supported by the same deep foundation as the perimeter walls of the home, and they usually are supported towards the center of the home where the support beams are typically located.  Sagging floors may be caused by extensive water damage, pest problems, improper initial construction, recent structural changes, or damage to support beams.

Understanding Floor Joists

Most floor joists are either made from natural lumber, cut from fresh trees, or engineered lumber, a combination of strips of wood glued together in patterns.  Engineered lumber is more commonly used because it’s easier to predict expansion and contraction than with natural lumber.  Floor joists are layered perpendicular to support beams or supporting walls.

The “joist span” is the space covered by floor joists between support beams.  The joist span can range anywhere from a couple of feet to over twenty feet, depending on the size of the floor and the placement of support beams.  The “joist spacing” refers to the distance between floor joists.  Most floor joists are spaced between 12 inches and 16 inches apart.

Causes of Sagging Floor Joists

When you notice your floor has started to sag, it may be because of sagging floor joists.  If you live in a home with a basement, check the support beams downstairs.  A concrete basement floor provides the best support for posts and beams.  Wood or dirt floors create a greater risk for posts and beams, even if they are surrounded by a concrete base.  As the posts or beams deteriorate, the entire house will settle over time.  You can check the integrity of the home’s floor by poking a tool, like a screwdriver, into the floor joists around the post or beam.  A soft or mushy floor is a bad sign, and could also be the reason your upstairs floors are sagging.  If your basement does have a wood or dirt floor, this may be a good time to upgrade to concrete to seal the area and prevent ongoing issues.

Moisture and seasonal pests may also lead to sagging floor joists.  If you’re in the midst of a rainy season or recently experienced a massive snowmelt, that moisture may seep into your basement or crawlspace and dampen the rest of your home.  In the summer months, carpenter ants are a common problem and in the spring it could be termites.  Sometimes you can easily spot the damage, when the floor joists have obvious holes, other times it could help to hire an exterminator to inspect for you and do a preventative service.  Even if you fix the sagging floor joists, a recurrent pest problem will just cause the floors to sag again.

If you’ve recently had electrical, plumbing, or HVAC work done recently, that could also be the problem.  A sloppy contractor may have cut into your floor joists and jeopardized the integrity of the support systems.  When you have any type of repair job done on your home, it’s important to work with a licensed professional.  If a mistake is made, then someone is accountable to either fix the problem or refund your payment.  Your home’s floor system is never a time to cut corners either.  Problems below the main floor can impact the entire home.

Ways to Fix Sagging Floor Joists

When you’ve identified the cause of your sagging floor joists, you can figure out how to fix them.  In some cases, you can take on this job yourself, but if it’s a more severe problem you’re going to want to hire a professional.

Depending on the extent of the damage, you can usually fix sagging floor joists through:

  • Reinforcing – add steel I-beams with permanent jacks to shorten the floor joist spans to address floor bounce on sagging.
  • Sistering – identical lumber (either natural or engineered) can be screwed to existing floor joists.
  • Sistering with a Filch Plate – instead of a bolt, using ¼ inch to ½ inch piece of steel or plywood to attach the identical lumber.
  • Jacking – install a permanent jack or posts beneath the floor to slowly return it to its original shape, and then replace with a permanent post or beam.
  • Beam Replacement- replace the existing, deteriorated wood beams with steel I-beams and permanent jacks.

The good news is, sagging floor joists can be repaired.  How long this repair will take, depends on what’s going on beneath your floors.  Reinforcing and sistering are relatively quick repairs, but jacking will take longer to resettle your floor.  It probably took years for your floor to settle, so in some cases you can’t jack it up right away.  If the floor joists require jacking and not just reinforcing or sistering, this is a good time to consult a professional.  Taking on a major job like jacking yourself could end up causing much more damage if not done properly.

We offer a free home inspection to give you an idea of how extensive your floor joist damage is and what you should do.  Floor joist sagging may be an easily fixable solution, or it might be the sign of severe structural damage.