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Preparing an Unfinished Basement for Renovation

Having your basement renovated is a big deal and can be really exciting! However, going from unfinished to finished does require some preparation. Unfinished basements often come with a lot of little problems that can’t simply be built over top of. Let’s check out some of the best ways you can prepare your unfinished basement for renovation.

Removing Mold

The first step to preparing an unfinished basement for renovation is removing any mold in the basement. After removing anything and everything stored in the basement, ensuring there’s nothing growing in it is vital. If you put flooring, wallpaper, or anything else over mold like a bandaid, it will continue growing and destroy your renovation work. That’s thousands of dollars down the drain.

Removing mold can be done in many ways. Check out our last article to see how you can do this for your basement.

Removing Moisture

Once you’ve removed any mold, it’s time to get rid of moisture. While tackling the source is best done in the next step, there’s one other thing you should be doing. Buy a dehumidifier and set it up in your basement. This will pull moisture from the air, ensuring there’s no condensation or damp that would allow more mold to grow. If your moisture issues are a bit bigger than stone walls with condensation, the next two steps are worth considering.

Exterior Basement Waterproofing or Damp Proofing

Exterior basement waterproofing and damp proofing are extremely important if you have moisture or leaks coming through the basement wall from the ground outside. Water in the soil surrounding your basement walls can often find its way through the stone. Not only does this cause moisture or leaks inside your basement, it also actively erodes your basement walls. That’s not great for the structure of your home.

When POM Waterproofing does exterior basement waterproofing, we dig a trench around the basement walls. Next, we apply a liquid membrane that provides us a smooth surface for our solid membrane. This membrane completely blocks soil and water from touching your basement walls. Damp proofing is a similar process without the solid membrane, for problems that are more “moist” than “leak.”

A lot of people are under the false assumption that you can just fill in wall cracks with epoxy or something from the inside. This is actually a really bad idea. Filling in cracks in your basement walls from the inside traps water in the walls. The moisture from the soil can still get into the walls, it just won’t be able to get out on the inside. This water is then free to erode, freeze, expand, and more, causing even more damage to your walls.

Installing a Sump Pump

If you have moisture or water coming up from the floor or ground in your basement, you need a sump pump. Preparing an unfinished basement with a sump pump will prevent mold from growing underneath your new floors. It will also prevent water damage to said floors. Learn more about sump pumps here.

How to Remove Mold from a Damp Basement

Mold growth in an unfinished basement is extremely common, but that doesn’t mean we should ignore it. Far from it! We should make haste to remove it. Mold is never great for humans. Even mild types without mycotoxins can cause respiratory issues, especially in those with sensitive lungs or asthma. So, how do you remove mold from a damp basement? There are a lot of ways, so let’s take a look at some of them.

Find the Source

Before going through the effort to remove mold from a damp basement, you should first find the source. If you remove the mold and don’t attack the source, it will likely just grow back. Some of the most common sources for basement mold are:

Basement Wall Leaks

If your basement walls are surrounded by damp soil on the outside, the moisture or water from that soil can come in through the walls. Microscopic cracks are large enough for water to get through. This can lead to basement wall leaks. This is fixed with exterior basement waterproofing or damp proofing.


If your basement walls are cold and the inside of the house is warm and humid, moisture from the air will cling to the cold walls like a cold glass of lemonade in summer. This moisture is much easier to solve by introducing a dehumidifier after killing the existing mold.

Rising Ground Water

Water rising up from the ground won’t be fixed with either of the previous solutions. Instead, you’ll need to consider a sump pump, which collects basement moisture and water. It then pumps the water away from the house through a drain.

Kill the Mold

Killing mold comes in many forms. Let’s take a brief look at the most popular solutions.


While bleach is cheap and effective, it can only be used on surfaces it won’t damage. For an unfinished basement with cement or stone walls and floor, this shouldn’t be a problem. However, the room should be heavily ventilated. If you have no basement windows, or they’re very small, it’s recommended to use something else.

Bleach can be applied with a bleach sprayer. These are often used to kill mold on exterior house walls and can usually be bought at a hardware store.


By mixing 1 cup of borax with a gallon of water, you can spray it onto walls in the same manner as bleach. Once applied, you should scrub with a sponge or brush. This will clean off any mold and also deodorize the area. While borax doesn’t need to be cleaned off the walls when you’re done, we still recommend it.


Concrobium is slightly more expensive, but is non-toxic. This is an EPA-approved mold killing chemical. It can be used on things like plastic without damaging them, unlike bleach. Plus, once you’ve treated an area with concrobium, it will no longer grow mold in the future.

Hydrogen Peroxide

Hydrogen peroxide mixed with water can be sprayed on just like the other solutions. After sitting for ten minutes, it should be scrubbed with a brush. It’s non-toxic, but you may want to wipe walls down when you’re done to remove the killed mold.

White Vinegar or Grapefruit Seed Extract

White vinegar is a great household cleaner, and that doesn’t end with mold. Vinegar can be sprayed or poured on mold and then wiped off after 5 minutes. Because it’s non-toxic and doesn’t tend to damage things, it can also be used on many types of porous surfaces. 

Any fabrics that have gotten mold on them can also be saved with vinegar. They can be washed in a washing machine with a cup of bleach instead of soap. Once you’ve checked they’re mold free, wash a second time with soap to remove the smell of vinegar. When they come out, they’ll be good as new.

Grapefruit Seed Extract

Grapefruit seed extract can be mixed with equal parts water, sprayed on, left for 5 minutes, and then wiped off. It also prevents future mold growth on the cleaned areas.

Tea Tree Oil

Finally, we’ve got tea tree oil. This is a natural fungicide and is very effective. Mix with water, shaking to mix well, then spray it onto effected areas and scrub away the mold.