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Sagging Floors

Sagging floors are not just unsightly; they can be dangerous. As such, it is important to learn to spot the red flags and warning signs before the problem escalates.

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If you have noticed the floors in your home are starting to bounce, dip, or sag underfoot, or they look uneven, you should start investigating immediately. Sagging floors are a sign of structural instability somewhere in your home, and when left unattended, the issue can quickly escalate until the floor in question collapses. If there are multiple underlying causes at work, which is often the case, these issues are also likely to grow over time, leaving you with a bigger and bigger mess to deal with as time goes by. 

What Can Cause Floors to Sag? 

When your floors start to sag the base cause will either be a lack of support or damage to the floorboards themselves. Of course, the underlying causes of this weakness can be many and varied. In fact, there is usually more than one issue at work when it comes to sagging flooring. These are just some of the most obvious and serious red flags to look out for. 

Damaged Joists   

Damaged joists or beams in your crawl space are sure to cause the floors above to sag and, eventually, crack or collapse. Joists can become damaged in a number of ways, but the most common culprits are termites, dampness, mold, and foundation damage. While pests, mold, and dampness destroy the joists themselves, foundation damage is a more widespread issue. 

Foundation Damage 

Foundation settlement and subsidence are two sides of the same coin and they can both undermine your crawl space’s ability to support your floors. This is usually caused by the way in which the foundation sinks, leaving a space between the joist and the floor. This leaves the floor unable to stand up to the weight of daily use. 

Persistent Dampness 

If you have problems with dampness and humidity in your crawl space, it is far more likely that you will find you have issues with rot and mold. When rot and mold get into wooden joists in your crawl space, they will start to sag under the weight and pressure of day-to-day use. Of course, in some cases, a sagging floor can cause dampness as it pulls away from the walls, causing small cracks that let water into your home. 

Whatever the cause of your sagging floors, however, it is important that you recognize and rectify it quickly. Issues like this only get more severe over time, which means it will never be easier or cheaper to fix than they are right now, especially when you take into consideration the secondary and tertiary issues that are likely to form over time.    

Sagging Floors: The Problem Signs 

The first step toward fixing any problem is recognizing that there is a problem and taking measure of the scope. Of course, there’s very little you can do to diagnose a structural issue like this as a non-professional, but you can be on the lookout for these warning signs and alert a professional if you see any of them. 

Floor and Wall Gaps 

If you notice gaps between your walls and floors or feel that there are more drafts circulating in certain parts of your home than there used to be, it is likely that your floor is starting to sag. As floorboards sink into the crawl space, either because their supports are damaged or because the foundation is starting to sink, they can start to pull away from the walls. 

This can be quite a small gap at first, but as the space between the floorboards and the joists and beams that are meant to support them gets wider, the gap will too. As well as leaving your flooring unstable, this will also make the temperatures in your home unstable as the drafts from the colder environment in your crawl space circulate your home. 

Bounciness Underfoot  

One of the earliest signs of damage to your crawl space supports is a slight bounciness underfoot. When the floorboards feel springy under your feet this is a sign that whatever support system should be in place has either started to fail or has become separated from the flooring. Over time, this bounciness will develop into a more pronounced bend and eventually the floor will begin to sag visibly. If you investigate the cause of this bounciness early, however, you may be able to avoid more pronounced damage. 


By the time a noticeable, visible unevenness has formed in your flooring, the problem that is causing your flooring to sag will have advanced significantly. A visible dip is a sign that the floorboards have not only been deprived of support but that they have started to warp as a result of the strain being placed on them. This is a serious red flag that requires speedy intervention; by the time a permanent dip has formed, the floor in question will have lost a significant amount of its structural integrity. 

Increased Interior Humidity 

An increase in relative humidity inside your property can be caused by many things, including damage to your crawl space and flooring. While this makes it an unreliable tool for diagnosing damage, it is a very good sign that your home is in need of attention from a professional. If you notice a sudden increase in humidity, start seeing condensation, or you notice musty odors around your home you should call an expert ASAP. 

Should You Worry About Sagging Floors? 

While sagging floors may not be the most dramatic of issues, you should take them seriously. It could take years or even decades for a floor to collapse if the damage is minor at first, but if the issue is left completely unaddressed, it is almost certain that this will be the eventual result. In the meantime, sagging floors can cause other problems in your home. 

The problem is that sagging floors can be a cause of more serious damage and a symptom of it. For example, a sagging floor could be the result of foundation settlement or subsidence, but it can also cause foundation issues if it is serious enough. This happens because of the way the edges of the floor can pull inward, sometimes causing the foundation to shift or crack. 

Furthermore, there is a chance that sagging floors could impact the rest of your home (this is unlikely, but it can happen). This is most common when the floors that are sagging are in the upper levels of a property. Finally, sagging floors can work in tandem with other issues to cause more damage to your property. 

Sagging Floors


If you have noticed a sudden change in certain sections of your flooring there could be a number of issues at work. Sagging, however, is primarily an issue of support, or lack thereof. If you have noticed sagging in sections of your flooring, the problem is likely to be found in your crawl space. 

Improperly Placed Supports 

If the supports in your crawl space have been placed improperly, or there are too few supporting beams or joists in place in your crawl space, your floor will start to sag over time. This is because the boards themselves are bearing too much weight without support. While healthy flooring should stand up to general use, damage will form over time. 

Floorboards that lack the proper support will feel bouncy underfoot and will begin to dip in the middle over time. As they become damaged and start to sag, you may also notice a gap between the floor and walls. This issue can be fixed by adding additional supports in strategic places in your property’s crawl space.   

Damaged Support Joists 

Even crawl spaces that have adequate support beams and joists in place can start to sag over time, impacting the flooring above. This generally happens as a result of damage to support joists. The most common causes of damage to support joists are dampness and foundational problems. These issues affect joists in very different ways, of course. 

Dampness, for example, is far more likely to cause wooden support joists to rot and lose their ability to bear the weight placed upon them. By contrast, foundation problems like settlement can cause uneven flooring by causing support beams to sink with the flooring, thereby leaving a gap between the support and the floor above. 

Sistering is the process of adding material to a damaged joist to bolster it. If the cause of your sagging floors is damage to support joists, sistering is a potential solution that many DIY blogs will suggest. Of course, we do not suggest that you try to implement a DIY fix at all, but sistering is a particularly inefficient solution for damaged joists. 

Sistering is a Delay Method  

Choosing to sister damaged joists in your crawl space will provide a little extra support to the floor above, but it really amounts to a method of buying time (assuming it is done well). Even the best sistering will only delay the breakdown of a damaged joist; over time, the sister material is likely to succumb to the same pressure, or else be rendered ineffective when the joist breaks down entirely. 

If the process of sistering is unsuccessful or undertaken poorly, it could actually speed up the breakdown of the joist as a whole. This generally happens because of the way the joist must be moved during the process. This weakens them and can even leave them more vulnerable to mold and mildew growth as well as pest infestation. 

Your Overall Repair Costs Will Increase 

Whether the process of sistering is successful or not, you will face a higher overall repair cost when you choose to sister a cracked or damaged joist. The joist is still likely to break down and require replacement at some point. This means you are paying for the sister materials as well as the eventual replacement joist. 

As such, it is far more cost-effective to invest in replacement joists or heavy-duty jack posts as soon as you see sagging in your floor. This will prevent damage from taking root in your flooring as a whole, but will also keep your repair costs low. 

No, the floor support systems that are used to replace damaged joists and address other underlying causes of sagging floors are specialist tools that are best deployed by crawl space repair professionals. 

A DIY Fix Could Go Wrong  

If you try to implement a DIY fix on your own, there are a number of things that could go wrong. First and foremost, unless you have the training and experience to complete structural repairs like this, there is a chance you could injure yourself in the process. Secondly, you could cause more damage to your home by implementing a solution improperly. 

Finally, there is always a chance that you will not correctly diagnose the cause of your sagging floors. If this happens and you install the wrong solution, you will end up with an increased repair bill overall, either because the solution has to be removed and replaced or because it causes issues within your home. As such, it is far better to let a professional deal with the issue. 

An Expert Will Give You Better Results 

There are a number of benefits to letting a crawl space professional deal with the required repairs inside your home. A professional has the training, skills, and experience to make sure that all underlying causes have been properly identified and accounted for before the repair process starts. They also have access to the best repair products. 

Finally, hiring an expert to undertake repairs to your property’s home comes with certain guarantees. For a start, you can expect all work to be carried out to a high standard when you bring in experts. You will also be guaranteed support should something go wrong during the repair process. Of course, this is not likely when you have skilled help, but it’s good to know you will have backup if there is an issue. 

What to Do About Your Sagging Floors  

If you have noticed a visible sag in your flooring or you suspect your floor may be beginning to sag, there are a few things you should do to ensure the problem is properly dealt with. First and foremost, you should look around your property as much as possible and make a note of specific warning signs and red flags that you find. Musty smells, mold, cracks, signs of pest infestation, or general humidity are all signs that something is at work in your home. If you are able and confident you can also make a quick survey of your crawl space. Take a note of what you see and contact a professional. 

Book a Professional Inspection 

Colorado locals like Complete Basement Systems often offer free inspections to homeowners who are concerned about the health of their homes. We urge you to take advantage of this. A professional inspection will highlight the issues at play and ensure that you have the best possible understanding of the damage in your home. 

Professionals will also be able to give you a reliable idea of what kind of work is needed to return your home to top condition. Here at Complete Basement Systems, we offer a same-day, no-obligation estimate for the cost of all suggested repairs. This ensures that you can shop around and make the best possible choice for yourself. 

Get the Right Solutions 

By having a professional assess your home you will ensure that you get the right solutions for you. It also ensures that you get the best possible results; whether you need drains, a dehumidifier, or crawl space supports, a professional will use the best products efficiently. This is just one of the reasons we never suggest DIY; an amateur just cannot get the same results as an expert. 

In most cases, a sagging floor will either require foundation repair, joist/beam replacement, or heavy-duty support jacks to ensure the results are permanent. Sistering a seriously damaged joist may be an option for stabilizing a situation until a proper repair can be completed, but it should not be used as a permanent repair. 

Stay on Top of Maintenance 

Once the repairs are complete, you should consider the benefits of a regular maintenance schedule. While this can seem like an unnecessary cost and hassle, it can actually save you time and money in the long run. When you book regular maintenance you are: 

  • More likely to catch problems early 
  • Less likely to experience unexpected issues 
  • More likely to save money in the long run 

Just like a car, a property that is well cared for is less likely to break down or underperform. If you take care of your property, it will take care of you and a regular maintenance schedule is an easy way to do this. 

Call Complete Basement Systems for the Best Results 

If you have started to notice warning signs of damage in your home, whether it’s increasing humidity and energy bills, visible cracks and gaps in your floors and walls, or simply a musty odor that won’t go away, it’s time to call Complete Basement Systems. Our team can be reached directly via phone or our contact form

Our team has been serving the people of Colorado Springs and Denver, CO, for years; we know what it takes to keep a property healthy through the hot summers and hard winters. Better yet, we have the specialist skills and tools to deal with whatever your home throws at us. That’s why we offer free inspections and estimates to concerned property owners. We believe that our work and reputation speak for themselves and will never pressure you to make a quick choice. 

You can arrange an inspection with our team quickly and easily; you will get a same-day written estimate and a guarantee that we will be on hand to help if things escalate while you are making up your mind. If you decide to work with us, you can count on a quick and efficient repair process that ensures minimal disruption to your home and daily routine. 

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