How to Deodorize Your Subfloor: Our Complete Guide

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It’s not every day that you have the expertise to fathom what happens underneath your hardwood flooring. The plywood and other sealants for hardwood flooring may protect the subfloor from moisture and scratches. But if you notice telltale signs like the presence of mildew and molds, a musky smell, and squeaking sounds, it is time to renovate the whole floor.

Every house has a signature odor depending on the occupant’s household items and cleaning standards. However, a house with a musty smell is a sign of subfloor rot or damage. Perhaps your house started smelling after a plumbing mishap, electrical damage, or storm. Whatever the case, identifying the cause of the smell is the first step to devising methods of eliminating it. We have highlighted why your subfloor is smelly, how to know if it is rotting, and the tips for deodorizing it.

Why is my subfloor smelly?

If your home is relatively old, chances are your floorboards could be rotting away. When your floorboard has been invaded by moisture, it turns into molds, causing a musty smell. Your pet’s urine or any other liquids spillage can seep into the deepest layers of your subfloor, putting your floor at the risk of rotting. Here are some reasons why your subfloor is smelly:


Houses that are regularly infested by pesky pests and other animals are more prone to foul odors. Vermin not only eat through wood, but they also leave their dropping in the subfloor. Over time, their deposits decompose, leaving a musty smell. If you notice pests roaming around your house, it is time to seek a good pest extermination service to end the menace.


Your subfloor is the most accessible spot for molds, primarily if your house is in a riparian area. Molds grow and multiply rapidly in areas with a lot of moisture and little-to-no ventilation. As molds continue spreading, they release some compounds that can emit a bad smell. The only way to prevent them is by ensuring your floor is dry, and the room is well aerated.


Floods cause the water table to rise, further permeating to the subfloor. While you might not prevent the rains, sealing your subfloor through several layers can prevent the moisture from seeping through to your floor.

Pet urine

Furry friends’ urine, when left uncleaned, can cause a foul smell on your floor. The more you leave pet urine on your floor, the higher the chances of penetrating to the deepest layers of your hardwood floor.

How to deodorize subfloor

Deodorizing your subfloor is the best way to get rid of the musty smell that could be filling your room. However, you might want to plan for this for at least two days. Follow these easy steps:

Step 1: Moving your furniture

The whole subfloor requires deodorizing, and that could mean moving your furniture to another room. You can also remove any wall hanging to allow you to clean the walls. If your upper flooring is removable, take out the top layer.

Step 2: Vacuum and mop the floor

Vacuuming removes any debris that could be hiding under your furniture. Using warm soapy water, dip the mop and clean from one corner of the room to another. Rinse off the floor with cold water. Ensure you change the water multiple times to achieve a spotless look.

Step 3: Bleach your floor

Mix bleach or vinegar in a ratio of 1:3. Now mop the floor with the solution and let the floor dry completely. Ensure you open the windows and doors to allow fast drying.

Step 4: Seal the floor

Sealing the floor with oil-based paint protects the subfloor from stains and odors in the future. Assuming the product has directions, ensure you follow them to the letter. Most likely, you apply the second layer once the base coat is dry.

Step 5: Let your floor dry for at least two days

As earlier mentioned, this project can go for three days. The paint will take at least 48 hours to dry before replacing the carpet and furniture.

If the musty smell is due to a plumbing mishap, you may need to call a flooring contractor to replace the wood from layer to layer. If the subfloor looks swollen, chances are the wood underneath could be rotting. The only solution you have is replacing the entire floor.

How to know if the subfloor is rotting

Hardwood subfloor may rot from water damage or any other activities that allow moisture to permeate through it. Sometimes, noticing if it is rotting can be challenging, particularly if your subfloor is sealed. There are a few signs that your subfloor is rotting, which we will explain here:

Watch out for stains

Stubborn stains, whether from pet urine or water, can signify subfloor rotting. That area with the stain will have to replace lest the damage spreads to other parts of your room.

Pay attention to sagging parts

Naturally, wood expands or shrinks in size depending on how long it comes into contact with water. However, urine or water-soaked wood will tremendously expand, causing it to sag. You can feel the sagginess while walking on the floor. In other cases, walking on such a floor may feel springy. Either way, wood sagginess is an indication that there is a rot issue.

Presence of molds and mildew

If you notice your house has mold or mildew and don’t know where it is emanating from, chances are the moisture in your subflooring could be the cause. The presence of mold and mildew is not only a health concern, but it could also be a sign that your flooring investment needs professional intervention.

Unless you have a background understanding of how subflooring structures work, it would be best to call a contractor to inspect the rot or damage. Performing the inspection on your own can expose you to harmful particles that can permeate your skin and eyes. Therefore, ensure you wear personal protective clothing like a facemask, safety glasses, overalls, and gloves.

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Joe McGuinty
I’ve been working with floors for over 12 years. I started as a flooring contractor, primarily in materials selection. Then, I switched careers into accounting, so my wife and I began buying, renovating, and re-selling homes on the side. You’d be surprised how much value you can add to a home simply by adding new floors.

1 thought on “How to Deodorize Your Subfloor: Our Complete Guide”

  1. I have a second floor apartment which has had carpet for 30 years. It has a bad, stale odor. I’m removing all of the carpet and simply laying down new carpet and rugs. I’m concerned that the odor (not from pets or moisture)is in the subfloor. What would you suggest?


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