Removing Basement Odors

Don’t feel bad because basements frequently have that old, mildewy smell.

When something smells “off”, it simply needs to be cleaned, decaying items removed, and the environmental conditions changed to stop further odors from developing.

Deodorizers and air fresheners make it smell better, but the effect is a temporary mask. It is far more important in the long run to get the odor under control and fix the problem cause before it worsens.

There are 2 easy steps to take when it comes to basement odors:

  1. Remove or repair the problem that is causing the foul smell.
  2. Clean the area to reduce the smell, control and and prevent any odor from coming back.

Luckily, there are some common things that cause odor to develop, and they are easily fixed. Find the solution to your odor problem by following these tips below.

Causes of Old, Musty, Moldy, Mildewy & Smelly Basements:

Basements are one of the most common odor producers in the home, right behind the refrigerator and the cat box. There are several things that can cause basement odors. These are the most common causes of smelly basements and what you need to do to fix it:

Inadequate Cleaning:

The Problem: You know the old saying: “Out of sight, out of mind”. Dust, dirt, grime, cobwebs and decay develops and builds up over time. Rodents and insects can take up residence without you knowing and create foul odors, unhealthy and unsanitary living conditions for you and your family. Mold and mildew put off foul odors that can be absorbed and spread to stored items.

The Fix: Give the basement a good overall cleaning. Start at the ceiling, clean down the walls and behind every item. Use bleach, borax or vinegar to clean and control odor. Clear out old junk stored in the basement. Remove things that absorb moisture or can put off bad smells such as clothing or carpet. A clean area doesn’t just look better, it smells better too. Clutter reduces air flow and mildew frequently develops on decaying items.

Now, once your basement is nice and clean and the clutter and junk are cleared out, check these other areas that may be causing the smell.


The Problem: One of the most common problems with the basement is the amount of moisture. Moisture causes mold, mildew, bacteria, fungal growth and causes wood, fabric and paper to start to rot. The very first thing to do is to get the basement dry. Even before you start cleaning, get the humidity down.

The Fix: You need to dry it out. To do this, use a dehumidifier and air out the location by opening windows. If you see water leaking from faucets or pipes or cracks in your foundation you must get that repaired to stop water from leaking into the area. If you see water stains, investigate the source and get it fixed. Allowing water to accumulate will cause more serious problems than just a bad smell. You must get these taken care of before they damage the home’s foundation.

Poor Air Circulation:

The Problem: Poor air circulation all by itself isn’t a cause of basement odor, but it does make it worse by allowing air to become stagnant and allow bad smells to become more obvious. Moving air also helps water to evaporate. Stagnant air makes mold and mildew worse when spores are released into the air and easily spread to other damp areas.

The Fix: Get the air moving by opening a window, turning on a fan, opening the doors or other methods.

Low Light and Temperature:

The Problem: Low lighting and air temperature can also promote odors. Dark, damp low light and air circulation creates the perfect environment for mold and mildew to grow or basement contents to decay unseen.

The Fix: Bring up the air temperature by using a portable area heater, turn on the lights and open the curtains. Heated rooms help water to evaporate You’ll be able to see the problem areas more easily in the light.

Mold and Mildew Growth:

The Problem:  Mold, mildew and fungus grows in damp areas with low lighting and thrive with poor air circulation. These organisms put off a gas that we most commonly associate with a smelly basement. Poor air circulation makes the smell worse and allows the spread of mold and mildew to other areas with time.

The Fix: You need to clean up moldy areas and scrub away visible stains. Borax is the perfect thing to use to clean this because it’s a natural mineral cleaner that also kills fungus (fungicide) and prevents further regrowth. It’s used in laundry soap. It’s the main ingredient in the product 20 Mule Team.

To Clean It-To make your mold and mildew cleaning solution mix the following in a bucket:

  • one cup of borax cleaner
  • one gallon of hot water

Use a scrub brush to clean the area and follow with a rinse of clean water as borax will leave a residue.

To Remove Stains- Remove stains and fight off mold and mildew regrowth with a bleach and water solution:

  • 2 cups of bleach
  • 2 quarts of hot water

Pour the solution into a spray bottle and work your way around spraying areas where you see visible staining, or suspect are causing odor problems. Keep in mind that there is water in this solution, so use sparingly to avoid contributing to a moisture problem.

Bleach will liquefy, sanitize and remove the color (bleach it!) on contact, depending on the surface it’s being used on.

Chlorine bleach is a very good sanitizer but I don’t use bleach frequently. Because it bleaches everything it comes into contact with I find it can cause more harm than good if you accidentally get it on an unintended surface. But this is one project where it is justified because it works like no other cleaning chemical will do.

Bleach is strongly alkaline and is very harsh. It may be a commonly used product, but you should respect it too. It will erode and corrode many things, and make the surface very slippery. It will burn your skin if it is not rinsed off. Bleach also removes the color from fabric on contact with no second chances. So rinse the area with plain water after using. Also, never use bleach in conjunction with any other cleaning product. It will react to many things and put off a toxic gas that could be very serious in an area of low air circulation.

How to Keep Your Basement Smelling Fresh:

There are several things that you can do to keep the odors at bay and keep your basement smelling fresh and clean.

  • Keep the home and the basement adequately ventilated. Air needs to flow through the home to allow for it to be kept clean. To make sure this happens, have your air ducts cleaned and also have your ventilation system checked yearly.
  • Control the humidity. The biggest odor causing problem in homes is that of mildew and mold. Use ventilation, windows, dehumidifiers and effective means for keeping water out to keep the level of humidity down.
  • Clean your dryer vent. Start outside where it exits and follow it down into the home to the base of the dryer. Blocked dryer vents allow moisture to build up in the home. If the dryer is in the basement, this can be the original source of basement odors to start with. Rodents can take up residence in the vent attracted to the lint that makes a nice nest and warm temperatures
  • Waterproof the basement. Water is the cause of many air quality problems. Make sure your basement is waterproof. A small leak can cause a tremendous amount of moisture and cause the other side of the home to smell bad.
  • Keep the home clean. Get the garbage out of the house quickly; keep the floors clean and pills cleaned up. Take care of those places that people like to avoid like the basement and the garage. Use products that will eliminate mold and mildew from your home.
  • Repair all leaks. If you suspect that your foundation or the beams in your home have gotten wet or damaged, have a professional come out and make sure. Weakened structures are not safe and will cause you to become injured and cause odor in the home.