What Are These Black, Smelly Stains On The Hardwood Floor Under The Carpet?

So, you pulled back the carpet in your new home to reveal beautiful antique hardwood floorboards throughout the entire house. You couldn't be more delighted, except for one problem: ugly, smelly black stains in a few areas of the house. Don't worry! There's a solution.

Pet Problems

Although it's impossible to say for sure, the most likely cause is pet urine. Even the most well-trained pets have accidents sometimes, and if that urine soaks through the carpet to the floorboards underneath, the buildup of uric salt crystals can discolor the hardwood. In addition, acidic urine can also burn the tannins in hardwood flooring, which can contribute to the stain. Of course, the smell is the biggest indicator that pet urine is the problem. This smell can persist for years under carpet because it's impossible to clean with carpet covering it. 

These stains might be concentrated in one favored location, or randomly distributed throughout the house, depending on the habits and preferences of the pet. If the most recent owner of the house had a cat or a dog, then these stains could be very recent. If not, these stains could be decades old, depending on the ownership history and age of the house. Either way, these stains are treatable. 

Hydrogen Peroxide

Pour or spray hydrogen peroxide directly on the stains, then give it time to dry. The stains should be greatly diminished by the time the hydrogen peroxide has soaked into the floor and evaporated. If you can still see the edges of the stains, pour more hydrogen peroxide onto the floor boards. Pour enough that the entire stain is covered with liquid. Allow the stains one more time to dry.


When this is done, you'll need to refinish the floors. Sand away the old finish on the floors and then apply new finish to the naked wood. If the stains are extensive and spread throughout the entire house, refinishing the entire house is the most sensible course of action. However, if only one or two stains are found in your home, you can try to get away with refinishing the affected areas only.

To do this, use light sandpaper to sand off the finish in the area where the stain was located. Remember to sand in the direction of the grain. Finally, apply a layer of polyurethane to the unfinished wood and allow it to dry.

If the wood is a light blond color, you may notice that the old varnish on the wood has yellowed over time. If this is the case, the new finish won't match the old finish. To counteract this effect, apply a light application of a yellow stain to the unfinished part of the floor before applying the polyurethane. If this doesn't work and you're still unsatisfied with the results, refinishing the entire floor may be your best option. 

To talk to a professional about hardwood flooring, contact a company such as Thayer Decorating Center

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One of the biggest challenges of leasing a retail space is the build-to-suit lease clause. If you're signing a lease on a commercial property, you need to understand what to expect from the planning and construction phases. The first time I signed a lease like this, I had no idea that there were some modifications that couldn't be made, leaving me with a building I couldn't do what I wanted with. I created this site to help others just like you understand what the process entails so that they can be fully prepared and avoid the mistakes that I made.


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