Basic Structure of a Floor



One of the most important parts of any buildings structure is its floor system.


The floor system carries the weight of
interior walls, roof, furniture, appliances, finished flooring, etc.
— not to mention the people and fur-babies who are inside!


How well the floor structure is designed and built
will determine how much weight the floor can carry.


Most floors in residential homes consist of four layers.

From the top down, they are as pictured ⇒


The finished, visible floor that you and walk on.

We know your primary concern is #1 on the list.
Floors Etc. is concerned about all 4.
Because if #2–4 aren’t in excellent condition,
then #1 will have problems sooner rather than later…
…and your investment will suffer.


Just under the visible floor covering.

  • Provides a smooth, flat surface.
  • Can also act as cushion, sound barrier, moisture barrier, etc.

Floors Etc. will tell you if your flooring project
needs an underlayment during your in-home assessment.


However, if your project calls for installation on a cement slab
or if it involves new carpet, laminate or LVT | resilient flooring,
you will most likely need some sort of underlayment.

Flooring underlayment is a thin material (usually only about ¼” or ½” thick) that rests between the floor covering above and the subfloor below. Unlike the subfloor, which is part of a home’s framework and structure, the underlayment is less about structure than about providing a smooth, consistent surface to allow for an easy, attractive installation of the floor covering. Underlayment also improves adhesion, ensuring the floor covering will properly affix to subfloor (as required). And, firm underlayment can even improve structural stability.

Have you ever walked on a carpet and appreciated how soft and resilient it feels? That undoubtedly has as much to do with the quality of pad than the actual carpet. Good padding protects your carpet, makes it last longer, and feel better. Your carpet pad will be out of sight once everything is installed – don’t let it be out of mind when making your carpet selection.

The correct cushion is important for maintaining the life and look of your carpet. According to the Carpet and Rug Institute, all residential carpets need a resilient, firm cushion of 7/16″ and no less than 1/4″ with 6 pounds cubic feet density. Polyurethane foams, including “rebond” fiber, or rubber are good options.
  • Floors Etc. uses a standard 8-pound 1/2″ pad with all residential carpets.
  • Premium / upgraded pads (e.g.: antimicrobial, moisture barrier, luxe foam, etc.) are also available at an additional cost per square yard.


Floors Etc. Pro Tip
Check with the carpet manufacturer to see if a specific cushion / pad is required.

The right kind of carpet pad will:
  • Act like a cushion, absorbing the force your feet impress upon your floors
    • This prevents your carpet from matting and crushing underfoot
  • Offer its own level of soil and stain protection
  • Provide an added thermal insulation and sound barrier
  • Provide ventilation between the carpet and the floor (makes vacuuming easier, and more efficient)

The wrong kind of carpet pad will:
  • Possibly void your warranty
  • Potentially cause the carpet to wrinkle, induce buckling
  • Increase wear and tear on the carpet.
  • Will considerably shorten your carpet’s life.

Overwhelmed by information? Let us help guide you through the process.


The very bottom layer of your flooring.

  • Stabilizes the foundation
  • Creates a firm base, holding up all of the above layers of flooring — and everything else in your home
  • Improves the overall lifespan of the floor — creating a higher value for the investment

Subfloors are more important than most homeowners realize.
Since they do their work below the surface, people do not always realize the true value of a subfloor until it starts to have issues.
Don’t ignore your uneven or failing subfloor.

The subfloor is the thick flat surface on which all other layers rest. Usually made of plywood, plank, OSB (19/32” to 1 1/8” thick) or concrete, this is a structural layer that provides strength and rigidity to the floor system when attached to the floor joists. Even though it is not seen by anyone, it affects every aspect of the floor.
The Importance of Subfloor Care:
  • Maintains overall strength of floor
  • Keeps floor safe and level
  • Preserves beauty and aesthetics of floor covering
  • Assures longevity of finish floor

Having proper subfloors is crucial to the look and function of the floors that sit above them. When subfloors weaken, they can dip, sink, or become slanted, and the entire floor can be adversely affected. It is important that subfloors remain strong and level to retain their usefulness
It is critical to properly level and prepare the subfloor prior to installation of underlayment or floor covering – a well-prepared surface forms your flooring’s foundation. Your new floors are only as good as the subfloor that you are installing over. A level, well-prepared subfloor will lengthen the life of your floor, and prevent gaps and noisy planks.
Proper subfloor preparation and suitable underlayment installation are essential for a trouble-free job. Not prepping a floor correctly will undoubtedly lead to future and more costly problems. Floors Etc. always takes the time and effort up front to prep each floor surface in order to successfully avoid these kinds of preventable flooring failures.
5 important things we always remember in subfloor prep:
    1. Clean
    2. Dry
    3. Level
    4. Structurally Sound
    5. Smooth
Most homes require some subfloor work before we can begin installation to ensure levelness and flatness and to ensure that your subfloor is within manufacturer specifications – so we always check to see if your subfloor is level before installation. Unfortunately, we cannot determine how level your subfloor is until the existing flooring is removed. If you know if any existing subfloor issues such as: creaks, bouncing, softness, or other damage, please let us know at the time of measure Here are some of our most common subfloor issues that we encounter:
High and Low Spots
  • If you have a concrete subfloor, there is a good chance we will need to prep before we can install your new hard surface floor covering. Sometimes we can “spot level” certain areas, other times we need to level the entire area. We refer to this process as “floating” the floor.
Squeaks and Creaks
  • It is common in both older and newer homes to have creaks when walking over the floors. Most of the time the creaks are caused from the subfloor coming loose from the framing.
    • If we know about this ahead of time, we can screw down these areas to help minimize these.

DISCLAIMER: We are normally successful in this, but sometimes the creaks are caused by things that cannot be repaired; we will advise you if this is the case.

Uneven Plywood
  • In Houston and Gulf Coast region, we all know it’s humid and it rains – and sometimes this can cause swelling and warping of the subfloor that needs to be remedied before your new floor can be installed.
    • If this is the case, Floor Etc. will discuss options and costs with you prior to moving forward.
Sinking Floors

Our expert craftsmen have the experience and the knowledge to ensure
that your finish floor is installed correctly
and on a solid, properly prepared subfloor
with the appropriate underlayment
making it a source of pride and beauty in your home for years to come.


Lateral wooden framing members.

  • They are typically made from 2 X 10 or 2 X 12 lumber or engineered Microlam / LVL beams.
  • If you have a concrete slab floor, you will not have joists.