Subfloor Water Damage

“Cleaning up spilled coffee on the kitchen floor only takes a minute. When you clean carpets or fix hardwood floors, you have to pay attention to your home’s subflooring as you work through the job of cleaning your home’s subflooring. Recovering from water damage caused by a burst pipe or storm flooding can take days.”


Subfloor Water Damage


After flooding, is it possible to dry a subfloor, or do you have to replace it entirely? How is subfloor water damage handled? Subfloor water damage is a big project. It would be best if you took action as soon as possible, regardless of whether you repair sections or replace the entire expanse.


The Subfloor: What Is It and Why Is It Important?

A subfloor underneath your floor serves as the building’s skeletal structure. It usually consists of softwood or plywood. It spans the many floor joints. Most sheets are four feet wide and twelve feet long.


Damaged Subflooring Usually Doesn’t Require Replacement.

In severe subfloor water damage, such as flooding or prolonged moisture exposure, damaged sections may need to be removed to avoid mold growth and ensure structural integrity. In addition to fire damage and pest infestation, homeowners may have to replace subflooring because of other issues.


The Causes of Water Damage under the Floor

Various sources can cause water damage under a floor; how much damage occurs depends on how much water the floor has been exposed to and for how long. Even a small, constant leak can cause significant damage.

Damage can occur in a range of timelines. If there is a substantial amount of water, such as from flooding, the water can seep into the floors immediately, but smaller amounts from slow leaks might take months (or even years) to reveal themselves.

It is also important to consider the flooring material when determining the rate at which damage occurs. For example, hardwood floors are more prone to damage than tiles or concrete floors.

Moreover, the water source—whether clean water from a pipe, grey water from an appliance, or black water from sewage—can also influence its severity and type.


Subfloor Water Damage: How to Identify Them

The damage to a subfloor may not be immediately obvious. Gradual damage (from leaks in the roof or window or plumbing problems) usually takes years to become evident.

To detect subflooring issues without pulling up your flooring, here are a few tell-tale signs:


It is creaking or squeaking.

Occasionally, flooring may squeak, but if certain areas are speaking louder or more areas are beginning to squeak, it could mean that sections are warping – a common water damage symptom.


Spots that are low or sinking.

Sinking low spots or sections of flooring is a common sign of water damage to the subfloor; however, it can also indicate a misaligned floor joint.


Tiles are loose.

Cracked or loose tiles can also indicate subflooring issues in high-moisture environments like bathrooms, kitchens, and laundry rooms. Cracked tiles or cement boards signify a sinking or curving subfloor. When a tile flexes and cracks due to a gap between it and the subfloor, it becomes a sign of a sinking or curling subfloor.


How Long Does It Take For Wood Floors To Become Damaged By Water?

Even small spills, such as those from sinks or water glasses, won’t damage your floors if you clean up as soon as they occur.

If wood remains exposed to elevated moisture for a long period, which can pose a high risk of damage, it can suffer damage from large water leaks, flooding from storms, or slow drips that go unnoticed for a long period. Whenever a floor floods from a storm, it is always a sign of water damage.


Is It Necessary To Replace A Subfloor That Has Been Damaged By Water Or Moisture?

When making this decision, you should consider three factors:

  • Is your subfloor water damaged structurally?
  • Is your subfloor going to be able to dry out?
  • Does your subfloor have a risk of contamination from flood or water damage?

When you see or suspect structural damage to your subfloor, you should replace or repair it immediately. Signs include loose flooring pieces and uneven floors.

If your subfloor is structurally unstable and wet or water-damaged, it can cause long-term problems, and simply replacing the wood floor on top won’t solve the problem. An unstable subfloor will likely make loud squeaks and creaks.


Professional can determine

A flooring or restoration professional can determine if it can dry your subfloor by testing it for moisture content. Subfloors can sometimes dry from below, either from a lower level or a crawlspace. However, you must replace it if your subfloor is too severely damaged and you cannot easily dry it.

When a flood occurs, it is important to consider any contaminants that may have entered your home. Even if the floor has dried out, residue will likely be left behind if sewage or chemicals were part of the liquid that flooded your floor. Removing and replacing the flooring and subfloor is best since they can be a potential source of bacteria and odors.


Water Damaged Subfloors: When Should I Replace Them

Subfloor replacement is only sometimes necessary when water damage occurs quickly. Sometimes, you can salvage your subfloor using remediation techniques, such as rapid structural drying. Most often, subfloors that have sustained repeated damage or are late in mitigation need replacement.


Water Damaged Subfloors: When Should I Replace Them


Working with a professional can help you identify and determine the extent and cause of the water damage to your subfloor, as well as prevent or remove mold or mildew growth.

Subflooring is a major weight-bearing component of your home. If your subflooring becomes damaged, your home could be damaged extensively, and your safety could be at risk.


A Step-by-Step Guide to Fixing subfloor water damage

A home’s most important architectural piece is one you rarely see: the subfloor (the floor that lies under the floor you walk on every day). It is typically a layer of 34-inch plywood under your carpet, vinyl, wood, or laminate flooring. When water seeps in, this layer becomes quite strong. Even a small leak can have devastating effects if left unattended.

If your subfloor suffers damage from water, it will quickly compromise the structure of your house. A leaky refrigerator or rainwater may seep into the subfloor and cause it to rot within a couple of days.

This is a common problem plaguing homeowners. You should assume damage to your subfloor has been there for a long time if it begins quickly but only occurs months or years later. Here’s how to try it yourself if you’re particularly good at DIY.


Obtain the necessary tools.

It is crucial to have the appropriate tools and equipment before starting. You’ll need these tools:

  • Measurement tape
  • The circular saw
  • The Hammer
  • The pry bar

Here is what you’ll need for materials:

  • Plywood 5/8″ thick
  • Lumber of 2 x 6
  • A galvanized nail


Look for leaks

To fix the subfloor, you must first locate the source of water. If rainwater is causing havoc, look for exterior cracks and repair them. If the leak continues, your repair will be in vain. You can also put a gutter or an awning over these exterior areas to redirect water away.

Start investigating your plumbing to see if the leak is interior. Whenever you encounter a plumbing problem, be cautious and contact an expert before trying to loosen it yourself. Even if you handle the rest of the repair, plumbing problems require permanent expert assistance.


Removing the flooring

When you cannot see the subfloor, you cannot solve subfloor problems. Wear rubber gloves and safety goggles, and start removing the top layer of flooring. Keep the floorboards for later replacement.

Pull back your carpet to the nearest wall to reach the edges of the carpet. You may need to remove the baseboards. After the repair, you can replace the damaged vinyl with a piece cut to your specifications if your flooring is vinyl.

Removing tile floors requires special equipment because tiles often adhere to cement boards between the subfloor and the floor. A contractor can remove tiles using equipment built to minimize tile damage when removing floors.


Calculate the damage amount.

After the flooring is removed, it is now possible to assess the extent of subfloor water damage. Rotted areas will buckle, discolor, and eat away, so mark them with chalk to indicate what needs removing. Identifying any underlying floor joists will help determine how to remove and reinstall subflooring.


Dispose of damaged areas.

If you have any areas susceptible to water damage or rot, you should get rid of them. Even if the damage has yet to be extensive, you should eliminate them. Any dampness will eventually lead to mold and rot. The repair must be complete and thorough if you want to preserve the structural integrity of your home.

Cutting with the circular saw, set to a depth of one inch, is the most precise way to remove rotten subfloor areas. Cut precisely along your chalk lines as close to the joists as possible. If necessary, use the pry bar to remove damaged sections. Make sure to remove all loose nails as well.


Reinforcing floor joists

You can only remove floor joists by interfering with your home’s structural integrity. If water damages your joists, you may need to dry and reinforce them.

The new 2×6 boards will compensate for the original joists’ water damage. Nailing the boards to the joists once they are dry will prevent additional damage.


Installation of a replacement

In the next step, measure the damaged areas of the subflooring and cut replacement plywood pieces. The replacement plywood should be 5/8″ thick and made from exterior-grade plywood. Should water damage trickle back into this grade, it can withstand moderate moisture before deteriorating.

You should measure and cut this step carefully to ensure that it is entirely accurate. To consider how natural growth occurs in wooden flooring, there should be a 1/8th of an inch gap between the old and the new subfloors. Before replacing the flooring, vacuum any debris and clear the area before you use new nails to attach the replacement subfloor. Place a hammer directly over the damaged area.

Contractors fix the top flooring last. This occurs after placing the subfloor and repairing the damage. The installation is complete after disposing of damaged subflooring and cleaning up the area, especially any loose nails.


Dealing with Tile Floors

Drying subfloors under tile floors can be difficult since they usually adhere to cement boards sandwiched between them.

Normally, you would pull up tiles to check for dampness, but restoration contractors use special equipment that leaves floors in place while they inspect. This saves you from removing tiles that don’t need repairing.


How about waterproof floors, laminates, and LVPs?

In many cases, vinyl and composite wood-look flooring claim to be 100% waterproof. This means the boards will not swell or warp when wet (usually as long as it dries within 24 hours).

Generally, these floors can handle light surface moisture and light water leaks if you dry them up quickly.

A flood or excessive water left on the floor for a long period may cause water to seep into the subfloor through the seams or around the edges. In these cases, we must remove and replace the floor. This is true even if the boards are waterproof. This enables the prevention of mold and the occurrence of drying.


What Is The Cost Of Repairing A Subfloor?

A sudden discovery of damage can be confusing as you rush to run numbers to determine how much it will cost. Several factors will determine the cost of repairing a subfloor. The cost varies greatly by the room size and how much the surface area is damaged. Does the damage affect just a corner or the entire room?

The price can be affected by the type of subfloor and the materials needed for repair. Most subfloors consist of plywood, but some use oriented strand board.


Bottom Line

The majority of floor replacements result from water damage. If you dry out your wood floor quickly after a spill or leak, it can withstand the water, but even floors marketed as waterproof need a replacement. When too much water seeps through your subfloor for too long.

If you have water-damaged floors, you must choose a new floor or find a qualified professional flooring contractor to replace them.