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wall and floor gaps, uneven floor

Sagging Floors

Sagging floors are a serious issue that should be addressed as soon as possible. Otherwise, the problem will only get worse over time and could ultimately lead to structural damage.

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A sagging floor is usually the result of a problem with the crawl space beneath the floor. The crawl space is the area between the floor and the ground, and it also acts as a foundation for your house. If the crawl space is too shallow or poorly ventilated, moisture levels can rise within it and cause your floor to sag.  

What Causes a Sagging Crawl Space? 

Sagging floors always stem from moisture problems in your crawl space. Keep in mind, moisture can spread throughout your crawl space in a few different ways, which we’ll outline in this section.  

open crawl space vent

Open Crawl Space Vents

Many crawl spaces have vents that run the length of their foundation walls. It was once thought that these open vents would allow moisture to freely escape from the crawl space. Instead, open crawl space vents allow outside air to continuously enter your crawl space. 

As a result of these open vents, the air in your crawl space becomes similar to the air outside. For example, it will be humid in your crawl space if it is humid outdoors. Since South Carolina experiences hot and humid summers, there will always be a risk of high humidity in your crawl space. Over time, this rising moisture can lead to wood rot or mold and will cause your floors to sag. 

Over Spanned Floor Joists

Built as a type of support beam in your crawl space, floor joists prevent your floor from collapsing. They operate best when installed close together so they can evenly disperse the weight of your floor and anything that sits on it. In rare cases, floor joists might be installed further apart than normal, and fail to provide enough support for your floors. Unfortunately, this design error results in slumping floors.  

Wood rot can also cause over spanned floor joists. If one floor joist becomes too damaged, the other floor joists will struggle to carry all of your home’s weight, resulting in drooping floors throughout your home. 

heavy rain and outside flooding

Groundwater and Runoff

Groundwater and runoff are other ways for moisture to enter your crawl space. Rain, snow, or sprinklers can drain water into the soil beneath your crawl space. Over time, the water eventually evaporates from the soil. Condensation, mold development, efflorescence, and wood rot are all problems that occur when water vapor travels throughout your crawl space.  

Runoff from precipitation is also a huge risk for homes built at the bottom of slopes, as water can pool beneath your property and cause similar water vapor problems. Once again, the collecting moisture will cause your floors to sag if left unchecked. 


Sagging floors are a severe safety threat, as they suggest that your home’s structural integrity is at risk of being damaged. If the floor sags more than a few inches, it may collapse completely, putting everyone in your house in danger. Sagging floors can also cause misalignment of doors and windows, making them harder to open and close. Sagging floors can even crack the walls of your home in extreme circumstances. If your floors begin to sag, you should contact a professional to assess the situation. Ignoring the issue could jeopardize your safety. 

Too much water in your crawl space can lead to standing water that takes a long time to drain.  Plus, an excessive amount of water may cause extensive damage brought on by wood rot or mold infestations. Furthermore, if water is absorbed into the soil under your crawl space, it will evaporate and seep into your crawl space’s walls and wooden support beams. Over time, this water vapor turns into condensation, and the water droplets cause more structural problems for the crawl space.  As you can see, water never goes away in your crawl space; it merely changes forms. 

Crawl space encapsulation is undoubtedly a wise investment. Wood rot, mold, and humdity are all hazards that encapsulation protects against. It also makes it more difficult for pests to crawl under your house, deterring animals from spreading feces and other foul odors beneath your floors. Not to mention, the clean white design of our encapsulation barrier makes your crawl space appear a lot more welcoming and easier to use for storage! Encapsulation saves you time, effort, and money in the long run. 

Mount Valley Foundation Services Can Help With Your Crawl Space Issues! 

Have you noticed musty odors in your home but can’t pinpoint where they are coming from? Do your floors feel like they are sagging, bouncy, or uneven? These issues indicate the presence of crawl space problems.  

Now that you understand the reasons these issues arise, contact us today so we can help protect your Charleston, Columbia, Greenville, or Savannah home. You don’t have to let crawl space problems creep up on you. Keep an eye out for these causes and stay prepared with our many crawl space solutions. 

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