How Thick Are Basement Floors?

Planning on building a basement floor but don't have a solid plan yet? Here are some important tips to consider on building your basement floor, since you might be wondering how thick to make it. We've researched the best basement floor thicknesses.

Basement floors have an average of 4” thick and should not be lower than 3.5” thick. We need to give importance to building a firm basement since this would be your house's foundation. If something happens to your basement, the entire house will be affected. 

If you want to learn more about the basics of concrete basement floors, please stay with us!

White painted walls of basement, How Thick Are Basement Floors?

Concrete Basement Flooring

Concrete is typically utilized to construct floors since it is significantly less expensive than other materials but it is one of the sturdiest. Here are some preparations for making a basement floor using concrete.

You will need to redo your calculations as cement is sold by the square yard to determine how much you require. 80 square feet of 4” thick concrete should be able to be poured with one cubic yard of concrete. 

To ensure that you don't run out of concrete before finishing your floor, multiply your total by at least a quarter of a square yard. Your concrete will become thinner and more brittle as you add more water to your cement and aggregate.

Interior of a basement under construction with dry walls

When pouring a basement floor, the ideal ratio is six gallons of water for every cubic foot of cement. 

Create a well in the middle of the dry ingredients, just like you would when creating a pie crust, and place them in a wheelbarrow. Stir the mixture thoroughly with a shovel after adding the water.

Immediately after mixing, your concrete needs to be poured because it will harden too much to work with after two to three hours.

Laying A Concrete Floor

  1. First, you need to determine the length, height, and depth of the basement. Using a shovel dig up the soil from the ground to your desired depth. Check the soil if it has a high-level concentration of clay or has moisture then add up 2” below for the gravel.
  2. Second, use a rake to flatten and smooth the ground to a level surface. Fill the gaps with dirt.
  3. Third, use a hand or mechanical tamper to pack the soil down.
  4. Fourth, pour 2” of small rounded gravel that will also help for the drainage system. Tamp down again until leveled and flat.
  5. And lastly, sprinkle the ground with water then start pouring the concrete. It is best to pour concrete when the temperature is between 50F and 70F so that it will set properly. Wait for three days to keep moisture and let the concrete cure.

We also need to consider the drainage, it must be well constructed and maintained not to create problems like cracks and floods. Surface water sources, sanitary or storm sewage backups, seepage or flow through the walls or foundation floor, or any of these things can cause flooding. 

Interior of a bright basement with blue painted walls matched with white trims and carpeted flooring

Please keep in mind that basements naturally have a high risk of flooding. It would also be best to install waterproofing systems to reduce problems with the water, it is also popular and no need for major exterior excavation. It can be done quickly and economically. Exterior drainage can also be an effective way.

If you got a freezing basement you could use the best flooring material which is a cork floating floor. To build an insulated floor add up a six-millimeter cork underlayment. This space could warm up the family during cold weather. 

Is Thicker Concrete Less Likely To Crack?

Concrete usually cracks when it is below the average of 4” thick. Thicker concrete may crack if the process had some problems such as excess water mix, rapid drying, improper strength poured on the job, and lack of control joints. 

Take note of proper timing, mixtures, and weights needed for the procedure. Putting the right amount and placing the correct reinforcement on the ground can build up an intact and smooth basement floor. 

Buildings or other properties use thicker concrete because they reflect it in the use of the basement. For example, when using the basement as a parking space. Knowing that plenty of cars would enter the space then automatically the basement needs to have a thicker basement floor that could support it.

How Strong Is 4 Inches Of Concrete?

4” thick concrete floors could hold up to 3,000 PSI. The component of making the concrete mixture such as the water measurement, the ratio of the cement and aggregates, and the temperature are factors in the floor’s strength. 

Depending on how it is used, the slab will be under a certain level of load. Concrete naturally wants to extend along its length and support weight. This indicates that despite being empty, it still has some residual stress from being stretched.

Interior of a basement under construction with unfinished walls and wooden moldings

If the concrete is loaded beyond what it can bear, this stress can lead it to break.

Having thicker concrete adds up additional money for the materials. However, conserving resources is better than over-building to avoid more expenses. Having a thinner measurement of a slab could result in cracks or worst breaking of the structure.

How Deep Should A Basement Slab Be?

A basement slab usually measures 3.5” to 4 “thick. A concrete basement without footings is known as a "slab basement." It is then poured after the basement walls are constructed. As a result, a floating slab of concrete is actually created as a floor. 

When a basement is described as having a floating slab, it signifies that the concrete floor can rise and fall as the ground shifts or freezes.

A hardwood flooring basement with green painted walls and white painted trims

In a structure that was previously constructed without a concrete basement floor, a slab basement is typically poured. To make a smooth, flat ground for the slab to rest upon, the dirt floor is leveled and compacted. 

Concrete is often poured into the space through a window in the foundation once it has been properly prepared. As a result, the dirt floor was replaced with a slab basement that provides a considerably more stable and hygienic surface. 

Read also, "Is My Basement Floor Sinking," to learn what warning signs to observe.

In Closing

White painted walls of basement

So if you are planning to build up your basement floor, do not forget the useful tips: Do the procedures correctly, combine the right mixtures, and consider the temperature when pouring. You will have a sturdy basement floor that your home could have. 

Wondering how to maintain a concrete basement floor? Please read our related post "Is My Basement Floor Sinking? How To Identify And Fix A Sinking Concrete Floor]."

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