How can I effectively eliminate mold in my damp unfinished basement crawl space without needing to demo the concrete floor?
Asked by Magdalena Martin 
5 months ago
Last Updated: June 12, 2024
I have this unfinished basement/crawl space that tends to get a little damp, and it seems like mold loves to take advantage of the conditions down there. Do you have a go-to method for getting rid of mold in situations like this? It’s all concrete, so thankfully no major renovations are needed. Currently, I’m using a fan to bring in fresh air through the basement door. Do you think an air purifier could help? Or maybe trying out that Mold Armor product from Home Depot? I really want to tackle this issue because I can definitely smell the mold lingering down there.
Can it be exposed to outdoor elements?
No, but we are currently addressing the issue of poor outside drainage around the house this spring. In the meantime, we need to figure out how to deal with the mold problem.
One of the best solutions is to set up an exhaust fan with an exhaust hood on one end of the crawlspace, and a fresh air intake hood on the other end. For the fresh air intake, you can use a homemade trap with an elbow or a combustion air pot. Connect it to a timer to run for 5 minutes every few hours to ensure proper air circulation.
So, I was thinking of something along these lines. Appreciate your input!
I actually have a different opinion on this. I think you should focus on fixing the drainage issue first before considering a dehumidifier. During the summer, the air outside is often humid, so bringing in more of that air with fans could make things worse. Instead, a dehumidifier in your basement will help remove moisture from the air as necessary.
I heard that ‘s basement will be fixed this spring, but I bet it will still get pretty damp down there. I have to run my dehumidifier all day, every day, and it’s really driving up my electric bills. I was wondering about the mold situation.
Home Depot has a mold killer that you can spray on, let it sit, then respray and scrub off. It leaves a coating to prevent regrowth.
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Hey , thanks for the suggestion! I’ll definitely check out that product.
Hey , it’s more about air exchange than humidity levels. An air exchanger with dehumidification could work well in this case. I have experience in HVAC and plumbing. Using an exhaust fan and fresh air intake is common in new home construction to keep the air circulating instead of becoming stagnant.
Consider using a dehumidifier or hanging items that can absorb moisture from the air.
Any ideas? My dehumidifier struggles to control basement moisture, especially during heavy summer rain, and it leads to high electric bills.
If your dehumidifier is causing high bills, there may be an issue with it. It might be time to consider getting a new one. Just like refrigerators, dehumidifiers should not be tipped over before plugging them in, as it can result in the loss or entrapment of coolant in the wrong part. They should always remain upright. Shipping a dehumidifier can be risky, as you have to trust the delivery person to handle it correctly.
Makes a solid point here. I believe it’s time for a new one.
Have you ever tried using mold bombs?
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Hey , I’m grateful for your suggestion!
When it comes to a basement dehumidifier, no matter the size, it won’t be able to handle rainwater getting in. However, it will dry out quickly if it’s a good one. I have a GE model from Home Depot with a built-in pump that automatically drains into my washer. It’s energy star rated too.
That sounds like a solid plan. My dehumidifier can hold a couple of gallons of water too, and I need to manually drain the bucket inside.
Hey , try keeping your humidity levels between 50-55% to prevent mold growth. Mold can start forming at 60% and over 70 degrees, but with 55% humidity in the air, water on the floor won’t cause mold. It will simply evaporate or be absorbed by the cement.
Hey , that’s interesting. I have water buildup on my floor too, and it sometimes drains into the floor drain but also forms pools. Looks like I’ll have to battle to keep the moisture levels down in the air dish.
You need to eliminate the mold by removing the source of moisture. Make sure to dry it out completely and prevent moisture from coming back.
I recently poured concrete and stone downstairs, but unfortunately water leaks through. I won’t be able to address it until I fix the drainage around the house next spring. For now, I have to focus on killing the mold.
If there’s moisture, the mold will simply grow back.
Got it, . Thanks for confirming.
Hey , I’m a bit confused… What specifically do you need?
Hey , did you have a chance to read the post? How do you usually get rid of mold?
Hey there! I’m a certified mold remediation technician. Can you tell me what type of surface the mold is growing on? The treatment methods can vary depending on the material.
Thanks for getting in touch. It seems like mostly stone and concrete, with a bit on some wood that I might be able to clean up.
Concrete typically doesn’t provide a suitable environment for microbial growth. The lack of structure makes it difficult for roots to attach. If there are signs of growth, it’s probably on another surface attached to it. People often mistake surface stains and effervescence for mold. Have you had the area tested? Do you have any photos? The wood part is easy to fix.
Sounds intriguing. No pictures, but the house has mainly stone and concrete walls with a wooden ceiling in the basement. I might need to clear out any stored items down there to check for mold on other surfaces. Since the basement is just used for storage, there could be something causing the mold growth.
If you experience high humidity, it’s very possible to have microbial growth on porous materials like drywall, insulation, fabric, and cushions. Unfortunately, these items are not cleanable as there is no product with a kill claim to effectively remediate and remove the hyphae. It will most likely grow back.
On the other hand, solid surfaces such as wood structures and framing can be cleaned by HEPA vacuuming, wet wiping with hydrogen peroxide, sanding, HEPA vacuuming again (HEPA sandwich), applying a final antimicrobial treatment, and then drying to standard.
For furniture or other items in stores, refinishing may be necessary, but it could be more cost-effective to replace them depending on the item.
If you decide to remediate on your own, be cautious to protect your home and health. Spreading spores can lead to recolonization in different areas, potentially worsening the problem.
Thanks for sharing, Seth! I took a screenshot so I can think more about it. Your help is much appreciated.
Of course. If you have any questions, feel free to send me a DM.
I appreciate it!
Operate dehumidifier throughout the season and apply TSP to problem areas
Can you explain what TSP is?
Hey, do you have any recommendations for a better dehumidifier like ? Mine doesn’t do a good job and it’s causing my electric bills to go up.
Hey, did you know that Trisodium Phosphate (TSP) is often used to get rid of mold and other stuff?
If you have a floor drain, most units offer the hose option. Ultimately, using a dehumidifier ends up being more cost-effective than dealing with property damage and potential health problems from mold. 🌀
I totally agree with you. Thanks for reminding me of that
It’s just moisture. Keep a big dehumidifier running all the time and make sure to empty it often. Dehumidifiers are categorized by “pints” per hour, so get a large one – I believe 60 pints is considered big. I tend to go overboard with things.
Hey , I appreciate your suggestion!
Oh, and , that brown trout is looking pretty nice by the way.
Hey , did you know that dehumidifiers are AHAM rated at PPD (pints per day)? The necessary PPD is based on cubic ft, but the efficiency is ultimately determined by the environment. The AHAM rating is specific to conditions like 90 degrees and 60% RH (relative humidity). If those conditions change, the PPD of the dehumidifier changes too. Just be careful not to ‘overdo things’ because you could end up over drying materials and causing unintentional damage.
Hey guys, just wanted to say thanks. I’m about to clean out the dehumidifier and get it running again. I actually need a new one, so I’ll do some research on what type to get moving forward.
I recommend getting a dehumidifier. I had a positive experience with a GE dehumidifier.
Make sure to get a dehumidifier that is the right size for your space. To clean mold on concrete or framework, use Fiberlock hydrogen peroxide cleaner. It’s effective to fog the area with this cleaner as well. Avoid using bleach, as it can release mycotoxins and this cleaner is a better alternative. If there are items in the affected area that can’t be cleaned, it’s best to discard them to prevent the spread of mold.
Hey , thanks for the solid advice! I’ll definitely steer clear of bleach. I’ve heard similar things from other people as well.
Hey , just a heads up that hydrogen peroxide can also lighten stains, so be careful with your belongings in case it discolors them when you use it. Using a spray bottle with sturdy brushes and paper towels might be a safer option.
Appreciate the extra advice. I think it’s a great suggestion too. For now, I’ll focus on decluttering and getting rid of unnecessary items to avoid wasting time cleaning things I don’t need. Currently, I’m cleaning the humidifier to get it up and running.
Make sure to clean it up and keep a dehumidifier running all day, every day.
Is currently handling it!
My dehumidifier is always set at 40% and I never unplug it. It’s running for about 7 months a year up here in Montreal, and my basement stays as dry as a bone.
Sounds good, I’ll definitely give that a try!