What Is Floating Slab?

A floating slab is another type of concrete slab laid on the ground with no support. The slab is built in two stages. Footings are cast individually in the first stage, and then the center floor of the slab is poured.

Because of the floating slabs, the ground preparation is reduced to a larger extent. Since the floating slab does not have a connection with the foundation, it is also called a monolithic slab.

This type of slab is used when the structure requires low bearing capacity. This foundation is suitable for small structures where a deeper structure is not required and when additional infrastructure is not needed.

Floating slabs are used as the foundation for small structures such as manufacturing workshops, sheds, and garages. Let’s discuss its construction process.

Why Use Floating Slab?

Floating slab is one of the most economical foundation construction methods. Traditional foundations require a strip footing with a frost wall above. The strip footing installed below the frost level is usually 4 inches below grade. The cost of a strip footing and frost wall is higher because more excavation, concrete, and labor are required.

Construction Procedure Of Floating Slab

To begin the construction of floating slabs, the planned building requires a stable foundation to completely sustain the entire weight of the superstructure.

As previously said, they are more commonly utilized in garages, home additions, and sheds that do not require large foundations. Structure-wise, these structures are light.

When compared to conventional slab construction, floating slabs are proven to be the most suited and cost-effective. The steps involved in the construction of a floating slab are described below.

1. Site preparation

The first step is to inspect the site where the floating slab will be built. Clear the site of any trees, small shrubs, or other debris. Then, make an excavation plan, including where to dig and where to take the soil.

2. Excavation

After all the preparation, the next step is to excavate the site. Excavate the area for the slab in accordance with the level. In this step, make a drainage channel on the sides for water to drain out through the gravel base.

  • Water will be removed from the concrete slab foundation by sealing the trench with geotextile and gravel. Make sure to cover this channel with waterproofing material.

3. Laying Gravel Base

In this step, gravel is spread over the area to allow unwanted water to drain.

4. Reinforcement For Slab

After laying the gravel base, the next step is to prepare reinforcement as per the structural design. Lapping should not occur in a single location during reinforcement; instead, it should occur in a different manner.

In addition, the reinforcement must be in accordance with the slab’s dimensions and specifications in order to strengthen the structure.

5. Shuttering

Now, it is time to begin shuttering. The formwork may require a smooth surface, proper alignment, and good quality work. To prevent the formwork from opening during concrete pouring, the cover block should be fixed after shuttering.

6. Concreting

Concrete can be made on-site in a concrete mixer, or ready-mixed concrete can be used for floating slab concreting. All materials are mixed in a proper mixer machine to achieve high strength.

Adequate compaction should be performed during the concreting process. Depending on the area and workmanship, it is compacted by hand or by a mechanical vibrator. After 24 hours, the shuttering should be removed.

7. Curing

The slab should be cured for seven days after removing the shuttering. Curing plays an important role in achieving the desired concrete strength. For curing, water is sprayed.

Advantages Of Floating Slab

 A floating slab can keep moisture out of the floor. It is used to separate the ground and the superstructure. Additionally, it protects against water and frost.

 This slab has the spreading property, which allows vertical loads or stresses to be distributed over a larger area.

 A floating slab is a good option if your home requires an extension. This slab serves as a physical barrier between the superstructure and the ground. This prevents water and frosting. As a result, this slab is mostly used in cold-weather construction.

Don’t require a wood flooring system & 8′-0″ basement wall.

 It requires less concrete and formwork for more economical and ecological construction.

 No footer trenches are required for this slab. They can be poured by trenching or excavating, which is a less expensive method. This slab causes no disturbance to the earth beneath it.

 Floating slabs can be heated with radiant floor heat, which provides a comfortable and balanced heat.

 Floating slabs are the best choice where the soil layer has a chance of shifting, primarily because of high moisture content.

 Cheaper house insurance because there is no basement to flood or chance of Radon gas infiltration.

Disadvantages Of Floating Slab

 It uses outdated technology.

 Less design resonance exists in foundations with floating slabs.

 Loss of storage space.

 Because there is no space in the floating slab for a sewage line, a trench must be dug during the construction.

 Floating slabs are ineffective for overloaded bearing structures.

 Repairing a floating slab is costly.

 Sometimes, the resale value of the house is lower because of the missing basement.


​Floating slabs are mostly used for the following buildings

  • Accessory buildings
  • Garages 
  • Drive sheds
  • Houses & cottages
  • Barns.

So that’s all about the floating slab. I hope you now have enough knowledge about it. Please share any questions you may have in the comments section.