What is Subfloor?

What Is Subfloor? (Definition, Purpose, Problems in Crawl Space Home)

You want to know *everything about everything* when it comes to getting your crawl space foundation repaired and your house leveled. Now you’ve arrived at the term “subfloor” and you want to know what it means. How do you know there’s something wrong with it? How does it get fixed?

Anchor Foundation Repair Bryan College Station

At Anchor Foundation Repair, we have inspected thousands and repaired hundreds of crawl space foundation homes in the Brazos Valley since 1985. We have repaired bathroom and kitchen floors that needed subfloor replacement. We’ve also gutted and rebuilt entire home floor systems and foundations. So yeah, we can tell you about subfloor . . . 

This article will offer a definition and explain the purpose of a subfloor in your pier and beam or block and base home. We will also discuss how you can tell if your subfloor is failing and how we typically fix it during the house leveling process.

Definition: What Is Subfloor?

A crawl space foundation is a complex wooden structure with layers of support and transition pieces that create the base of your home. 

Your crawl space foundation starts with piers and then sill beams rest on top of the piers. Then, floor joists are placed on top of the sills. The subfloor is the last layer, located on top of the floor joists, and underneath the finished visible flooring you see in your home.

what is subfloor?

subfloor noun: a rough floor laid as a base for a finished floor

The subfloor is the part of your foundation structure that rests on top of the joists. The subfloor makes a solid surface on which to place finished flooring. Some older homes were not built with subfloors and the original flooring was placed directly on the joists.

Older homes might also have the subfloor laying diagonally in ¾” tongue and groove material laid on top of the joists. Other homes will have the tongue and groove slats placed perpendicular to the joists.

Newer homes (or homes that have previous subfloor damage) will be repaired or rebuilt using plywood as the subfloor material.

Purpose: What Does Subfloor Do In My Crawl Space Foundation?

Well, we kinda already covered this as part of the definition, but that’s okay we can say it again. The subfloor rests on the joists and joists are typically placed 16 inches apart. Subfloor forms a solid surface with no space in between each piece of subfloor that rests on top of the joists. So when your nice flooring is put down, it’s placed onto another solid surface for full support.

pier and beam foundation repair

Problem Indicators: How Can I Tell if My Subfloor Is Failing?

Many things can go wrong in a crawl space foundation from settlement to wood rot to termites. Each problem part tends to have a different feeling *under your feet* when they are failing and not functioning properly. For subfloor in a crawl space home, the typical problem indicators are:

  • Soft, squishy, or spongy floors that feel like you might sink through them, and
  • The problem is most common in wet rooms like kitchens and baths due to moisture and water damage rotting out the subfloor.
damaged subfloor

Subfloor issues are more common in wet areas often due to a plumbing leak or just general moisture accumulation in that area. A subfloor can also become compromised throughout an entire home when prolonged drainage problems, poor ventilation, and excessive moisture issues are present under a home.

You should get subfloor issues addressed because there is likely something more going on under your home in the form of moisture damage and wood rot to other parts of the wooden foundation structure.

Problems in crawl space homes tend to have a domino effect where one problem causes other problems. So it’s best to handle subfloor issues as soon as possible to avoid compounding issues, although the problem likely has already compounded if it’s affecting the subfloor.

Fixing Subfloor During House Leveling

replacing subfloor with plywood

When a subfloor is damaged by moisture, wood rot, or termites, extensive work must be done to replace it. Since the subfloor is held up by floor joists and supports another lay of finish flooring, the ONLY repair approach for a compromised subfloor is complete removal and replacement from the top down. 

To fix your subfloor, we have to cut it out and rebuild it from within your living space. So, homeowners often need to move out when subfloor work is needed. You can’t really cook in your kitchen when there’s a hole in the floor and you can see exposed dirt a foot or two down through the open floor. 

It’s not that you couldn’t live in a home with this kind of work going on. But you might not want to, especially if the room or areas needing repair are vital to your everyday living like kitchens and bathrooms.

We’ve got a few ideas and solutions for homeowners who need to move out during the foundation repair process. If you think there’s a chance you will need to temporarily relocate, I highly recommend checking this out: Do I Need to Move Out or Can I Live at Home During Foundation Repair?

How Can You Know For Sure What Is Wrong With Your Subfloor?

pier and beam foundation repair and house leveling

Now that you know all about subfloor and what it takes to repair it, the first step to getting this kind of work done is to get an inspection and estimate for the work.

At Anchor Foundation Repair, we have developed a homeowner focused process to get your house leveling needs handled, and it starts with reaching out to Anchor online or by phone.

The most efficient way to get the process started is by, 1.) taking photos with your phone of any foundation concerns you see in the home, and then 2.) filling out this easy online contact form to submit your issue and photos and get in touch with our Estimation Team.