Thrasher has experience helping homeowners who have experienced their basement floors and interior footings being raised. This is called "heaving" and is less common than foundation settlement but can be devastating to interior finishing. Basement floor and interior footing heaving can be very destructive to a home, including cracks in basement floors, interior drywall, and uneven floors upstairs.
This phenomenon can be complicated to diagnose
That is partially because it is rarer, but also because a lot of the damage that it causes looks a lot like the exterior foundation is sinking. Instead, the interior floors and footings are going up and pushing the interior walls up into the second floor.
What causes basement floors and interior footings to "heave"? Typically heaving occurs when moisture is added to or returns to the soil, causing it to expand, which pushes up the floor slabs and interior footings. Heave usually occurs with newer homes. When a house is built, a hole is dug, and the hole remains exposed to sunlight, generally for several weeks. With so much direct sun exposure, moisture is removed from the soil, and the ground shrinks. This is especially true in the summer and if there is no rainfall during the time the soil is exposed.
When the basement floor slab is poured, over time, the moisture that once was in the soil returns, causing it to expand, pushing upwards on the basement floor slab and footings.
In other instances, Thrasher has witnessed heave when a home is built over an old agricultural field where the old crop wasn't fully excavated and removed. In this instance, the old crop is drawing moisture to the surface, causing the soil to expand.
Regardless of the cause of soil expansion, it is powerful and can take significant value away from a home.
Heaving can cause cracks in the basement floor slab and uneven floors, making finishing a basement much more difficult. When the soil heaving gets invasive, interior framed walls, load-bearing and non-load bearing get pushed upwards, affecting the primary floor framing system. Drywall cracks begin to appear, floors become out of level, and doors start not opening and closing correctly. Like foundation settlement, heave can be very invasive and can cause significant damage to the home.
Generally, soil heave from moisture under a slab will slow down significantly as the soil reaches its original moisture levels.
This means that the problem will get worse for a few years before slowing down. If the cosmetic damage isn't too bothersome, some homeowners may choose to live with the issue long term. In other cases, the damage will lead you to want a solution to get the home back to its original condition.
Several things can be done to address this problem, and the solution is dependent on the severity of the problem. Here are a few potential solutions based on the challenges that you are facing:
Basement Floor Slab
If the issue is primarily reserved for the basement floor slab being humped up in the middle, you may be able to address just the slab.
For example, if the basement is unfinished and the interior footings have not moved, you may remove and replace the basement slab. You will want to ensure that a geotechnical engineer reviews the soil and assists the concrete contractor in ensuring the underlying soil has the appropriate moisture content so that the issue doesn't reoccur. If the ground is especially problematic, it may need to be removed and replaced with a more competent material.
Basement Slab and Non-Load-Bearing Walls
If the problem is in a finished basement where the interior (non-load bearing) walls are being pushed up into the second-floor joists, you will have to take a more invasive approach. In most cases, you will want to remove the basement slab, excavate below the bottom of the slab about 12". Once this is done, you can install helical piles that will support a new structural slab. Then a void form can be established. This concrete form goes under the concrete and creates a space for the soil to move in without impacting the new structural concrete slab. Once the helical piles and void form are installed, a structural slab can be installed, and the basement can be updated. A solution like this will guarantee no further issue with a heave.
Basement Slab and Load-Bearing Walls
If the heave is also impacting the interior load-bearing walls, the problem is much more severe. This type of heave causes significant damage throughout all floors in the home and usually means the second story floors are out of level. In this case, all of the other remediation efforts listed above need to be taken with the addition of piers under the interior load bear walls and footings. By installing these interior piers, we can excavate under the interior footings, lower them back down to their original position, and install a void form under the footings to prevent future issues. This is the most invasive approach, but it will prevent further problems from occurring in the home.
Thrasher has a unique, geotechnical solution to basement floor heave that can restore your home's value. These types of problems are very complicated and will take a smart and well-planned approach. If you think you may be experiencing this problem, contact us for a free, no-obligation inspection and estimate from one of our experienced System Design Specialists.
Thrasher has a unique, geotechnical solution to basement floor heave that can restore your home's value. If you think you may be experiencing this problem, contact us for a free, no obligation inspection and estimate from one of our experienced System Design Specialists.