Layers of a Floor – Anatomy, and Parts (Illustrated)

A good floor system for your home or house is as good as it’s structural composition. Squeaks and sags can be avoided if you understand the anatomy of a floor. Other major problems can be avoided when the new floor covering interacts well with what’s below it.

The anatomy of the floor has many parts that add both the stability, comfort, and beauty of your house. The parts of the floor include; joists, the underlayment, subfloor (beams and adhesives), and coverings. When they are blended together they form a durable and stronger floor system.

Floors in your residential home, commercial space or house consist of four layers.

Layers of a Floor

The four layers that make up the wood floor system consist of; the Joists, Sub-floor, Underlayment, and Floor Covering. Discussed below are the four layers of a floor with their purpose on the top-down technique.

Parts of a floor, layers of a floor , anatomy of a floor

1. Floor Covering

Flooring covering also popularly known as the finish floor or flooring. This is the visible upper finished layer of a flooring system surface. It may include materials like hardwood planks, carpets, cork, linoleum, concrete, ceramic tile, and vinyl floorings. This is the layer you see daily, walk on, and place your furniture on among other items. It is the ultimate layer that covers the other structural layers of flooring. It’s the upper surface of a floor system structure

Wood Covering
Wood Types Covering

The flooring materials can be installed differently depending on the needs and requirements of a room. When selecting the flooring you need to consider, the area moisture content, cleaning and maintenance methods, durability, quality, and the feel and comfort it provides when walking on it.

Select and install durable floor coverings, like tile, concrete, hardwood, vinyl, and laminate in areas with high traffic or even where accidental spills may occur like the kitchen. Consider and pick a soft and invitingly textured covering like area rugs or carpets over hardwood in family rooms, dining rooms, and bedrooms.

Purpose of floor covering

The floor covering provides a smooth, durable, clean, impervious, hard, and attractive surface. The flooring provides a strong durable base that is easy to clean and maintain with a wide range of designs and styles to choose from. In general, it provides a finished material for us to walk on.

Here how to install floor covering and tips.

Floor Covering Installation Tips

2. Underlayment

What is an underlayment? This is a thin layer of material installed between other materials. Floor underlayment is mostly made from sponge rubber, foam, felt, crumb rubber, and recycled plastic.

The underlayment material is installed below the floor covering and placed on top of a sub-floor. Under the visible covering, there is a layer made of soft or foam-like materials with a thickness of between 1/4- or 1/2-inch.

The underlayments are available in different materials to choose from depending on the flooring needs and the type of the floor covering to be installed. Some common choices include; foam, hardboard, cork, plywood, and cement board. In case you considering installing engineered or hardwood flooring, the best underlayment may be foam or cork. However, cork may offer some added advantages to your flooring.

Purpose of floor Underlayment

The Purpose of floor underlayment is to provide comfort underfoot as well as reduce wear on the covering. Its purpose is to provide a smooth, flat surface for the floor covering. It also serves additional functions like deadening the sound of footsteps, softens the feeling underfoot, or even as a moisture barrier.

sub-floor underlayment

It also provides sound insulation, improves moisture resistance, retains warmth, heat, and even retard fire outbreaks. Underlayment in many cases helps to rectify sub-floor imperfections. Always pick the best underlayment for laminate, vinyl, and hardwood floors.

Here a video on how to underlay your floor.

How To Install Underlay [Floor]

3. Sub-floor

What is a sub-floor? This is a layer between the floor underlayment and the joists. Its sturdy structural part resting on top of the floor joists It acts as a foundation of the underlayment and the floor covering.

Sub-floor helps to make the floor smoother and comfortable to walk on. Sub-floor generally holds all the above layers plus people, furniture, pets, and everything in the house. the subfloor can be made from particleboard, OSB, Plywood, or concrete.

Sub-floor heater
Heated subfloor

This layer may be made of OSB (oriented strand board) or plywood. It is part of the house floor system construction used installed between the underlayment and floor covering, The OSB or plywood are commonly used as an integral material for the sub-flooring structure of the home flooring. Subfloor Increases the strength and rigidity of the floor system since it’s attached to the joists.

Purpose of Sub-floor

What is the purpose of the sub-floor? Subfloor provides the foundation of the floor. It levels the surface and makes it easier to install, the upper covering, hardwood, vinyl, linoleum tile, or even carpets. Sub-floor provides support and ultimately makes the floor look aesthetic.

There are some major problems that affect the sub-floor. In case you didn’t pay a lot of attention during the construction of the second most important structural element of your floor, you are bound to come along the sub-floor issue below.

  • Foul smell: This signify moisture build up-forming mold and mildew on the sub-floor. As such it may come from below or from the floor covering. Water moisture is one of the worst enemies of the sub-floor take necessary precautions
  • Sagging: Its a sigh of sub-floor getting worn out or there is a structural weakness.
  • Squeak sound as you walk on the floor: A new sound will always signify a damaged sub-floor and need to be fixed

How to install a sub-floor?

To build a good structural sound sub-floor, you need to know the no of layers you expect to build on top. Here is a video on how to install subfloor and prevent subfloor squeaks.

How To Install A Subfloor

TIP for Sub floor

  • Ensure you determine the sub-floor material and thickness carefully. Depending on your area, you may also consider things like heating vents, the area of installations, basement or crawlspace, and stairs above as well as the joist below.
Flooring anatomy sub floor, underlayment, floor covering, joist
  • The floor is great as its foundation. If you want to keep enjoying your floor aesthetic look, consider investing in its sub-floor. It plays a very important part in your home and making sure your floors stay beautiful and enjoying it for a long. Hire a flooring professional, the sub-floor issues can’t be diagnosed by you alone or not recommended as a DIY project

4. Joists

Also known as band sill. What is a joist? This is a structural form of a beam that spans horizontally between the foundation of a building or walls or two beams. They are lateral wooden framing members rest on foundation walls and beams and provide the structural support for the entire framing system.  Sometimes they’re noisy, squeak or bounce.

Purpose of Floor Joists

It provides the structural support of the entire floor, and at times may not consider as part of floor layers. Its an essential part of the layer matrix although in concrete slab floor it’s not there.

They are the pillars of the structure that support all the other parts of the floor, except on concrete slab. It supports a subfloor that spans over an open area. 

When joined with floor framing system the joists provide and enhance the stiffness of the sub-floor sheathing. This allows it to function as a horizontal diaphragm of the floor.

Flooring Joist
Flooring joist

The joist are mostly made from, laminated wood, engineered wood and dimensional lumber. The joist also has its challenges, especially after the sub floor has been installed

  • How do you replace damaged joists?
  • How to find it the joist on top of a subfloor?
  • The standard size of the joist

The joist span is determined by floor strength, wood species, joist spacing, depth of joist, spacing, and engineering. These will help determine the distance between support joists below the sub-floor. When the sub-floor is nailed on top of the floor joists, it forms the flooring system.

Joists are build to support the load on which the floor is built to bear. They are typically made from lumber or engineered microbial members. In combination with other joists, it provides support to the floor or even at times ceiling.

Here a video on how to install a floor joist

How to install Floor Joists

How do i find joist under sub-floor?

To find the joist under the sub-floor from the floor covering like carpet or hardwood floor requires the use of a hammer. Tap the floor from one edge or corner and listen for a thud sound. Generally, the most area will have a hollow sound, a thud sound signify the presence of joist. You can continue until you determine the area where the next joist is. Hoping the were installed with the same distance from one another, you can quicken the process by measuring the distance of the identifies joist to locate others.

What is the difference between a beam and a joist?

Joist and beams are structural flooring elements made for similar and related functions. They are the primary structural component for a floor and roof. Beams are large in size while joist are smaller. Beams are used to support the joists by providing support to the horizontal structure of the floor. Joists and beams can be made from solid and engineered wood or even steel. However, Joists are commonly made from solid lumber

Sources and References

Wikipedia: What is the flooring?

Britannica: What is floor covering?

1 thought on “Layers of a Floor – Anatomy, and Parts (Illustrated)”

  1. How do I know exactly what specific floor layers that are in my house? Does every type of floor have this same type of layering?


Leave a Comment