Where Are Floating Walls Required


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Floating walls are required in basements in Colorado, USA, where the clay-containing make-up of the soil leads to extreme moisture-related expansion and shrinkage of the ground surrounding the basement foundations.

The soil in some regions is prone to expansion and contraction. The movement that results from this can eventually damage the integrity of a building. To prevent this from happening, floating walls are constructed to adjust to the movement that arises from changes in the soil temperature.

Floating walls are still a strange concept to many people. So, in this article, I explain why floating walls are necessary, how to know if you need one, and what building codes have to say about floating walls.

Floating Walls Required in Colorado Basements

A study by the Colorado Geological Survey (CGS) estimates that the nation loses about $2 billion annually as a result of damages caused by expansive soils! 

Many regions in Colorado feature soils that are laced with expansive clays. The most popular is Bentonite, a type of clay that can absorb a significant amount of water molecules. This results in swelling when the moisture content is high and shrinkage as it reduces. 

How Does Bentonite Affect Buildings?

According to the Wyoming State Geological Survey (WSGS), Sodium Bentonite can absorb 10 times its weight in water. It can also expand up to 16% of its size. This feature makes builders adopt it as a foundation waterproofer. 

However, in areas like Colorado, where this expandable clay is already present in the soil, adequate procedures are to be followed in order to avoid serious structural issues like:

  • Broken foundations.
  • Cracked drywall.
  • Heaved floors that lead to cracks.
  • Damage to basement structures.
  • The building can also be completely destroyed in extreme situations.

If expansive soil is found in clay, a pier-supported foundation and floating basement walls are used to protect the integrity of the structure.

How Do Floating Walls Work?

Floating walls unlike regular basement walls do not sit directly on the floor slab. Instead, they sit between pressure-treated plates of 1-3″ and are anchored with extra-large 60D nails. This arrangement allows the wall to move slightly to accommodate any slab movement that might ensue due to changes in climate and temperature conditions of the soil. 

Floating Walls basic structure

Non-floating walls in vulnerable locations can push up the ceiling and floor joist when the soil becomes saturated. This causes significant damage not only to the basement but also to structures above and throughout the home over time.

If your basement is properly framed with floating walls, the few additional inches that the plate provides protect your home in case the floor heaves. So, you avoid serious issues and would only have to deal with cosmetic flaws like cracks in floor tiles and drywall. 

Are Floating Walls Required by Code?

There is no generalized code by the International Residential Code (IRC) on the installation of floating walls. However, in the Colorado Chapter of the International Code Council, floating walls are listed as a necessary basement finish requirement for areas that are subject to floor movement. 

For regions that do not have this problem, a floating wall is not required, except otherwise instructed by city codes. So, it is okay to build the type of wall that best suits your construction design if your city laws do not say otherwise. 

That’s why it is important to get building permits prior to the commencement of a project. The process of applying and acquiring a permit apprises you of instructions and safety practices that would ensure a long-lasting structure. 

How Do You Know if You Need Floating Walls?

Before building the foundation of any structure, a soil test is usually carried out. If expansive elements are found in the soil, then the necessary construction procedures are followed. Thus, in this case, floating walls would have to be built in the basement.

It’s general practice in Colorado to use floating walls because the soil in that region is subject to swelling and shrinking. So, if you live in this area, you would most likely have to build floating walls in your basement in accordance with the city’s code. 

Colorado is not the only area requiring floating walls; it is simply the most noticeable. However, if you want to learn more about whether you need floated basement walls, you can read: Do I Need Floating Walls in My Basement.

The damage caused by heaving soil happens over time and might not be noticed until considerable damage has been done. Therefore, if you notice cracks in your basement’s floor or drywall, it’s best to contact a professional to help determine the cause. If the cracks are caused by the heaving of the ground below the basement, then a floating wall might be required.

Where in Basement Are Floating Walls Necessary?

Based on the severity of soil expansion in the area, your city might have specific requirements for the placement of floating walls. Apart from city requirements, the purpose of the basement (if you have plans of turning it into a living area) would also affect the placement of walls.

Most people frame floating walls in the same locations as regular basement walls. It should essentially go around the edges of the basement. 

The walls can be covered by drywall and baseboards to improve their appearance.

Baseboard Molding 6" Height 96" Length Manufactured with Dense Architectural Polyurethane Compound (11 moldings)

The external walls of the basement can be constructed with regular concrete from floor to ceiling. 

What About Load-Bearing Walls?

Load-bearing walls as the name implies are designed so that they support the structures above them. They are constructed to carry a significant amount of weight. 

The composition of floating walls isn’t ideal for load-bearing purposes. Floated walls aren’t rooted to the ground so any weight that is placed on it would be transferred to the pressure-treated plates that they are resting on. These plates aren’t designed to hold up weight and neither are the other components of the wall. 

So, if your wall is designed to be load-bearing, it mustn’t be floated. Doing that would make your home a safety hazard. 

Are Floating Walls Required on the Main Floor?

The primary purpose of a floating wall is to prevent structural damage that could arise from heaving foundations or expansive soil. That’s why it is usually constructed in the basement, the part of the building closest to the foundation. 

Different walls like partition walls, cavity walls, load-bearing walls, and floating walls have functions they perform. Using one type of wall instead of another makes it ineffectual and might even lead to structural problems eventually.

With that said, floating walls aren’t required on the main floor because they wouldn’t be useful in that setting. 

Sources

https://coloradogeologicalsurvey.org/hazards/expansive-soil-rock/#

https://coloradobuildermag.com/build/bentonite-friend-and-foe/

https://www.wsgs.wyo.gov/products/wsgs-2014-bentonite-summary.pdf

https://coloradobuildermag.com/build/the-dangers-of-building-on-bentonite/?

https://s3-us-west-2.amazonaws.com/coloradochaptericc.org/uploads/2018/07/2018-IRC-Basement-Guide-.pdf

https://theconstructor.org/geotechnical/types-of-soil-tests-construction/12679/

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