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Overspanned Floor Joists

When floor joists over span, this can cause serious problems for your property. After all, these joists are all-important in supporting the main floor of your property.

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While most homeowners are acutely aware of the health of their walls and roof, few pay as much attention to the floor beneath their feet. This is partly because floor damage is not quite so obvious, but also because the floor is something we really take for granted in a property. Nonetheless, you should be keeping a close eye on your property’s flooring. Those little springy patches and light dips might seem entirely benign, but they are, in fact, signs of structural damage. 
If you are particularly unlucky, they could be signs of serious ongoing issues within your home. Issues with your flooring, like issues with your foundation, are not likely to resolve themselves or settle over time. Instead, they will continue to escalate until they are impossible to ignore. As such, it will always be quicker, easier, or cheaper to repair your floor the day you first notice issues. This is a good incentive to recognize early warning signs. 

floor joists

Spotting the Early Signs: Unevenness and Tension 

Your property’s main floor is supported by a system of sturdy joists that are specifically arranged and spaced to ensure that every part of the floor has the same level of support. This very particular layout is what ensures that your property’s floor is able to hold the weight of your furnishings and stand up to daily use. When these joists are improperly placed or become damaged, there are repercussions for your home. 
Springiness Underfoot 
If you notice that the floor has suddenly started to feel bouncy or springy, it is likely that there is some kind of issue at work. Your floor should feel stable when you walk on it. In fact, it should feel stable even if you jump on it. If you feel like you are bouncing, you should contact a professional for advice. This is a sign that this part of your floor lacks the proper support. 
Uneven floors are always a bad sign. A visible sag or dip to your floor is a strong indicator that you have damage to your flooring or the support joists underneath it. It may even tell you that the supports have been improperly placed. Worst of all, it may be a sign of advanced damage to your property, so you should prioritize an investigation. 
Floor and Wall Gaps 
Gaps between your floor and walls are another sign that your floor is not properly supported. This can occur either because the floor is bending sufficiently to pull itself away from the wall, or because the wall itself has started to lean. Often these two issues are connected, especially when the damage is advanced. 
Mold Growth 
Mold growth is caused by excessive humidity and the presence of mold spores. When these spores hit organic material—for example, exposed wooden support joists—they take root and form mold. Mold formations will eat away at wood over time and cause it to weaken. While this is a slow process, mold can undermine the strength of your supports and even have repercussions for your health. Mold can trigger allergies, cause headaches, and exacerbate respiratory conditions like asthma. 
If you see any of these signs in your home, you should contact a professional to assess the situation. This will ensure that you and your property are protected in the long run. Of course, these can be signs of many different issues. Over spanned joists are just one possibility. 

What Are Over Spanned Joists?  

While the term “over spanned joists” may seem like technical jargon, it is in fact a rather straightforward phrase that tells you exactly what it is referring to. You just need to know what joist spans are. 
The term “joist span” refers to the space between floor joists. More accurately, it refers to the ideal span between joists. An over span is when there is too much space between floor joists. This results in an unsuitable level of support being offered to the floor above. 
Working out the ideal joist span is by no means easy! You may think that it’s as simple as a bigger joist having a better load-bearing capacity, but this is not always the case. When figuring out load capacities, an architect must consider the wood species, the grade of lumber, the width and thickness of the floorboards, the estimated loads on the floor, and the length of the joists, as well as the span between them. 

What Causes Over Spanned Floor Joists? 

With all that in mind, it is pretty obvious that a simple miscalculation in design can lead to an over span of joists in any property. However, if this was the underlying cause, issues in a property would start to show themselves very quickly. 
As such, unless you have just moved into a new-build property, it is unlikely that poor design and planning are to blame for over spanning joists in your home. Other potential causes include: 
Foundation Damage 
If your property experienced foundational issues like settlement or subsidence, this could well affect your floor joists and lead to over spanning. Issues in a property’s foundation affect every part of a property over time, after all. If damage to your foundation begins to cause your walls to bow or lean, for example, this could damage your floor joists. Likewise, foundation damage can cause a spike in humidity and dampness within your home. 
Water Damage 
Water is an incredibly destructive substance when it comes to exposed wood in a property. If foundation damage, or any other issue, causes flooding, dampness, or humidity in your home, this will affect your floor joists. Mold is very likely to form in these environments, for example, and will eat away at any joist that it forms on. Likewise, serious flooding could cause the wood of the joists itself to start rotting. In this case, the load-bearing capacity of that joist will plummet, putting extra strain on the remaining healthy joists. 
Termites and other pests can easily lead to the over span of floor joists. They can do this in much the same way that wood rot or mold formation can: by damaging joists in a way that undermines their ability to support the floor above. Termites are relatively easy to spot for an expert, thanks to the telltale damage they leave on wood that they have made their home. They are less visible than pests like cockroaches, however, and so are generally not found until they do notable damage or until a routine inspection brings them to light. 
Poor Construction 
Poor construction is another common and obvious cause of joist over span. Unlike poor design, however, sub-standard construction will not necessarily start to take effect right away. The use of damaged or unsuitable wood, for example, will lead to damage over time, but this can be a surprising amount of time. Likewise, if a contractor was slightly off in their measurements, you could be left with joists that are a little too short or long. 
These issues will cause slightly different kinds of damage. Joists that are too short are more likely to slip, whereas joists that are too long are more likely to press against support beams. When this happens, it is likely that they will shift or cause cracks, thereby destabilizing your floor. 
These are not the only possible causes of joist over span, of course, but they are the most common. If otherwise healthy, well-placed joists begin to struggle over time, it is far more likely that there is more than one underlying cause at work. 

What Can Be Done About Over Spanned Joists? 

If you have started to notice signs of damage in your property’s flooring, it is a very good idea to check your crawl space for signs of damage. This is where the infrastructure that supports your floor is, after all, but it also contains many other valuable systems. These include your plumbing system, electrical wiring, and insulation, not to mention the top-most edge of your foundation.
Of course, many property owners don’t feel confident or comfortable traversing and inspecting their crawl space. As well as being very confined and uncomfortable, there is a chance that you will knock into or damage one of the other important systems that runs through this part of your home. Likewise, most homeowners don’t feel confident that they would recognize damage to support joists even if they were able to safely get close to them. 
As such, we recommend that you contact a professional when you feel that you might be dealing with the over span of your floor joists. This will ensure that the underlying causes are properly identified and that the solution is appropriate and well deployed. We do not, under any circumstances, recommend that you try to repair this issue alone. Not only is this a specialist task that requires experience and specialized equipment, but it could also be very dangerous for you and your property if you try to go it alone. In the very worst case, your floor could collapse, injuring you and anyone helping you. 

Over Spanned Joists


If you have noticed a slight sag or dip in your flooring, you should start investigating immediately. While this may seem like a minor issue, even a slight sag in your flooring can be indicative of a much bigger problem percolating beneath your home. 
Water Damage 
Water damage is one of the most common underlying issues when it comes to structural damage to a property. From drywall damage to mold formation, dampness and humidity have proven themselves, time and time again, to be destructive forces in a property. When it comes to your flooring, dampness and water damage can show themselves in two main ways. 
Firstly, water can cause the floorboards themselves to warp, become rotten, or be infested with mold. This will cause those individual floorboards to become weak and even sag, but will not affect the floor as a whole. Secondly, dampness and moisture in your crawl space can damage the support joists that hold up your floor. This is, of course, far more likely to damage your floor as a whole. 
Over Spanned Joists 
Over spanned is a term used to denote a specific kind of damage that reduces the load-bearing capacity of your property’s support joists. The ideal span of a particular joist can be very specific, so it is important to maintain their health once they have been set in place. Any kind of damage to them—for example, as a result of moisture or cracking—can quickly lead to sagging floors. 
As well as moisture and water damage, floor support joists can become over spanned as a result of foundation damage, improper measuring, or even structural issues like bowing walls. At the end of the day, the structure of your property exists in a delicate balance. Anything that upsets this balance can cause real issues for your home.  

Over spanning of the joists that support your property’s main floor is a serious issue that can have varied and unexpected side effects. As well as the obvious sag and unevenness that will develop in affected floors, there are other, arguably more serious issues to consider. 
Leaning or Bowing Walls  
Leaning and bowing walls are a fairly common side effect of over spanned joists. That’s because, when a floor begins to sag in a pronounced way, it can pull away from the wall. This will cause the wall to be destabilized and, over time, the wall will deviate from its intended position. When this happens, it will actually cause further damage to the floor. 
As such, these two issues are often connected and can form a somewhat vicious cycle. As a result, the joists will become weaker, causing the floor to sag further and the walls to bow or lean more severely. This can lead to issues with dampness and drafts, but also more serious repercussions, like the total collapse of certain walls or sections of flooring. 
Floor Collapse 
If left to percolate without intervention, over spanned floor joists will eventually lead to the collapse of the floor, either in sections or in totality. This is dangerous for obvious reasons. Any people, animals, or even furnishings in a room when this happens will face serious injury or damage. With that said, there are other, more long-lasting effects. 
The floor joists may primarily support your flooring, but they play an important role in supporting the structure of your home overall. When a section of a property’s floor collapses, even in isolation, the rest of the structure will be put under pressure or left with insufficient support. As a result, you may find that walls or even upper floors are in danger of meeting the same fate if you don’t act quickly.  

This is a complex issue that requires a particular skillset and tools to be correctly repaired. As such, there’s not much that you, as an amateur, can do to repair the problem. If you want to minimize the strain a damaged floor faces until a professional can attend, however, you could remove heavy furnishings from the area of the floor that is sagging. 
Do Not Attempt DIY 
While we understand that it can be tempting to save money by attempting a DIY fix, we recommend that you do not try this. There are many things that can go wrong when you get involved with structural repairs as an amateur. First and foremost, you could end up failing to diagnose the underlying causes properly. This will lead to you implementing the wrong repairs. 
Secondly, even if you do identify the correct issues and appropriate solutions, there is a chance that you could do more harm than good while undertaking those repairs. If you do this, you run the risk of causing the floor to collapse or even exacerbating co-occurring issues you were otherwise unaware of. This can be incredibly dangerous for you and anyone helping you.  
Call an Expert 
Professional repairs may seem costly, but you must remember that an expert not only has the skills, experience, and training to handle any underlying issues and secondary damage. They also have all the special tools that they will need. This means that the work will go smoothly and quickly once they start, and you can kick back and relax. 
Furthermore, professionals have access to high-quality, industry-standard products that are not always sold over the counter in hardware stores. As such, you are likely to get a more durable result from professional repairs. As you can see, professional work really pays for itself over time; you get a better, more durable result the first time a repair is undertaken. 

Complete Basement Systems is Here to Help 

Complete Basement Systems has been the go-to crawl space repair contractor for homeowners in and around Colorado Springs and Denver, CO, since we opened our doors in 1999. With a team of skilled and experienced specialists, we know what it takes to return a damaged and sagging floor to full health. Over our time in the business, we have dealt with many over spanned joists. We’ve also corrected the uneven, damaged floors that they have caused. 
If you notice signs of damage and over spanning in your home, we urge you to contact us directly to schedule a free inspection and repair estimate. When you contact our team, they will help you set a date and time that work best for you; they will also be happy to answer any questions you may have about the process. 
When your inspector arrives, they will conduct a thorough assessment of your home in order to gain an understanding of what forces are at work. When they have completed that inspection, they will provide you with a written quote for the work in question. This will be provided with no obligation to book repairs with us; our team will never pressure you to make a quick choice. We want you to feel that you have had all the time that you need to make the decision that is best for you and your home. 

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