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DIY Crawl Space Cleaning Guide

a dirty, moldy crawl space

Guide updated for 2024.

Things to Consider Before Cleaning Your Crawl Space

Mold in crawl spaces is very common, especially in wet areas like Indiana. It can often be corrected with a little patience and hard work. Of course, you could hire a professional mold company to do it, but there are reasons for wanting to do it yourself.

The Cost of Crawl Space Mold Remediation

The primary reason for wanting to clean up crawl space mold yourself is cost. This type of work can be very expensive, and if you’re the DIY type, you don’t want to part with your hard earned coin. We understand. We’re DIYers too, which is why we got into such a dirty business. It is likely that you can save some money doing the job yourself, but we will discuss some things besides cost that you may want to consider before getting into the nitty gritty.

Your Buyer May Want the Assurances of a Professional

One of the most common times to discover crawl space mold is in the middle of a real estate transaction. If you are selling your home, you may be required to disclose the presence, or history, of a mold issue (check with your real estate agent or lawyer about laws in your area). Disclosure of a mold issue can trigger panic in a potential buyer, and they may not be convinced that your DIY efforts are sufficient to correct the problem. The deal could fall through, and you could have issues finding another buyer.

Crawl Space Cleanup Is a Long, Dirty Job

Most do-it-yourselfers don’t mind getting a little dirty. However; over the years we have encountered many people who get started on their crawl space cleanup without realizing just how dirty, difficult, and time consuming it is to actually correct a crawl space mold problem. You should think long and hard about the commitments in your life, and how you want to spend your nights and weekends, before you take on a project like this. Of course, it may not be an issue if you have a couple of small spots in a localized area of your crawl space, but the project seems to grow exponentially if mold is spread throughout the space.

Consider Your Health

Severe Allergies or Sensitive Skin

If you experience severe allergies or sensitive skin, it isn’t wise to spend a lot of time in a crawl space. Even with the proper equipment, you could come into contact with mold, bacteria, cleaning chemicals, and all manners of dirt and grime.

Respiratory Issues

It may not be possible for you to work in your crawl space if you have respiratory issues. Even aside from the direct exposure to mold, dirt, bacteria, insulation particles, etc. that may be in the space, it might not be possible for you to spend prolonged periods wearing a respirator.


If you have an inability to be in small spaces for an extended period of time, you should avoid going into your crawl space. It is a dark, enclosed space that can strike fear into many. In fact, we have hired more than one employee that didn’t know they had claustrophobia until they put on a face mask and tried to work in a small space. We recommend putting on a respirator and closing yourself in a small closet to test yourself before crawling into your crawl space to work.

Other Health Concerns

You may have bad knees, a fear of spiders, or any number of other health issues to consider. Please pay attention to your health and perform an honest assessment of your abilities.

Think About Hiring a Professional

Given the reasons above, and others, we implore you to at least consider hiring a mold remediation professional. At Indiana Mold Remediation, we strive to provide you the best value possible; affordable crawl space solutions provided by our mold remediation experts. We guarantee our results, and our reputation and customer reviews speak for themselves. If you are outside of our service area, we know there are other reputable mold remediation companies who could give you an honest assessment and a fair deal. We may be able to refer you to somebody if we know a contractor in your area.

Supplies For Crawl Space Cleaning

Some items that you may need for your cleaning project include:

  • One or more of these cleaners
    • Oxiclean (or other percarbonate powder)
    • Bleach
    • Soap (Dish Soap, Simple Green, Castile Soap)
    • Borax
    • Washing Soda
    • Botanical/Natural Cleaners (Benefect, Thieves, Vinegar, etc.)
  • Personal Protection Equipment (PPE)
  • Pump Sprayer or other Spray Equipment
  • Soft Bristle Brush
  • High-Pressure Fan or several low-pressure fans
  • Extension Cord
  • Duct Tape

DIY Crawl Space Cleaning

If you’ve read this far, you have considered your options and decided to take the DIY route. Good for you! You’re in for an adventure that will lead to a marvelous sense of pride and the satisfaction of a job well done. We are here to be your guide, so pay attention to the steps below.

Eliminate the Source of Mold: Water Intrusion

Mold grows in crawl spaces for a variety of reasons, but they all start with water intrusion. The water can come from the ground up, from your house down, or even from the outside air. It is important to eliminate these water sources first to prevent the mold from returning after you’ve done the cleaning.

How Does Water Get Into My Crawl Space?

There are several ways water can get into the crawl space. Leaks or flooding might be obvious, but not all sources are. [ I recommend making the section below a tabbed section that only expands the section you’re looking at. Like a FAQ. ]

  • Evaporation from the Ground
  • Plumbing Leaks
  • Irrigation Systems, Downspouts, and Grading
  • Improper Drainage
  • Humidity in the Air
Evaporation of Water from the Ground

There is a lot of water naturally stored in the ground. Like, a lot. You may remember charts of the water cycle from grade school. It rains, water goes into the ground, it evaporates into the air, and then it rains again. It’s just part of the natural process of the earth.

The problem with this cycle, for your crawl space, is that the water evaporates into the space and causes the humidity level to rise. This can create perfect conditions for mold growth. The common way to prevent this is to use a vapor barrier to stop the cycle from occurring. This can be a simple layer of plastic covering the dirt or gravel in your crawl space, or a more comprehensive encapsulation system that prevents evaporation as well as some other sources of water intrusion. Indiana building code requires a vapor barrier that is at least 6 mil poly or thicker for new homes (check your local building codes), but some older homes may not have any vapor barrier at all. If your home is missing a vapor barrier, or it doesn’t cover the entire crawl space, you will want to correct the issue.

If you are going to install a new vapor barrier or encapsulation system, it may be best to wait until after the mold cleanup is done. Otherwise, you could cause mold, dirt, water, and chemicals to pool up on the new plastic.

Plumbing Leaks

This one should be a little more obvious to spot. Leaks from supply lines, drains, or even from heating and cooling systems can dump a lot of water into the crawl space. Often, we don’t know it is happening until it is too late. You will want to inspect for leaks, and have them repaired.

Irrigation Systems, Downspouts, and Grading

Water often enters the crawl space through the foundation. Irrigation systems and downspouts that are improperly installed can dump water at the base of your house. This water infiltrates into your crawl space, leading to mold growth. The same thing can happen when it rains if the ground isn’t properly graded to drain the rain water away from the house.

Extending downspouts and relocating irrigation away from the foundation are relatively easy fixes; however, grading issues are more complicated. If the grade of your yard is causing water intrusion through the foundation, you may need to contact a foundation expert.

Improper Drainage

Most crawl spaces, at least in Indiana, have a sump pump system to eject excess water from the crawl space. Often, there is a perimeter drain that carries water away from the foundation and empties into the sump pump system. This is a great last line of defense against water in your crawl space. When it works.

Check your sump pump and test it to make sure it is operating properly. If you don’t have a sump pump, and there is standing water in the crawl space, get one installed. You might need to call around to see who does this work; we install sump pumps, so you may want to ask your local mold contractor, foundation company or plumber.

Humidity in the Air

It’s more difficult to diagnose, and more difficult to solve, but in many places the humidity in the air can naturally be quite high. In Indiana, the hot summer air can enter your crawl space through the crawl space vents and cause mold growth. If you have no other obvious leaks or water intrusion, this may be your culprit. Possible solutions to this problem could be adding ventilation, encapsulating the crawl space in a vapor barrier that extends up the foundation walls, or adding dehumidifiers to keep the humidity levels down. If you cannot determine the cause of mold growth in your crawlspace, you should consider a mold inspection from a reputable contractor to help determine the cause even if you intend to do the remediation yourself.

This can be a complex situation. Enclosing the crawl space may be a solution, but could also contribute to your problems and make them worse. We recommend consulting with a crawl space professional before proceeding, even if you will be doing the work yourself.

Crawl Space Cleaning Procedure

Physical Mold Removal is the Goal

The goal of remediation in crawl spaces is to remove the visible surface mold growth, and staining from mold growth, on the structural framing. The vast majority of mold growth found in crawl space can be cleaned with a simple soap and water solution. When you are done, the wood in the crawl space should look clean, and new. Using paint or other encapsulants to seal the wood is not recommended and could cause you problems down the road.

Wear Appropriate Protective Equipment

Safety is paramount when performing this type of work. It is important to wear the correct personal protective equipment, PPE, but it is also important to ensure you are using it correctly. The proper order to put on your PPE is body, hands, face and lungs, eyes.

Protect Your Body

Wear older, long sleeved clothing that completely covers the body. Cover the clothing with a protective suit or coveralls. This prevents you from getting mold, chemicals and dirt on your skin and  tracking them back into your home.

Disposable coveralls are available at most hardware stores or can be ordered online. These suits can be reused until they are worn out. Moisture (or splash) resistant coveralls are preferred over synthetic dust suits or clothes and attached hoods and boot covers allow for maximum protection.

Protect Your Hands

To protect your hands, use thick, waterproof gloves. Disposable gloves are available online or at hardware stores; make sure that they are waterproof and chemical resistant.

Pull the gloves on with the cuffs over the coveralls. Use duct tape to attach the gloves to the coveralls. This prevents dirt, debris and cleaners from getting directly into the coveralls and onto your skin.

Protect Your Face and Lungs

Protect your lungs with a face mask or respirator. The bare minimum standard is an N-95 particulate mask, but higher levels of filtration are better. We encourage the use of full face respirators with organic vapor cartridges, as they will be the best protection for your face and lungs, from the mold as well as the cleaning chemicals. Full face respirators are available online and provide both respiratory and eye protection.

Make sure that the respirator is tight against the face and that the only air coming into the mask is through the filters. For full face respirators, placing your hands over the cartridges and breathing in should draw the mask to the face, no air should seep in through the seal. Men with beards can have an especially hard time getting a good seal and shaving may be needed.

Protect Your Eyes

If you do not opt to use a full face mask, wear goggles or safety glasses to prevent mold and chemicals from splashing into your eyes. You may need to take extra care to keep things from dripping or seeping behind your eye protection. We use, and strongly recommend, the full face respirator option.

Safety Tip, Confined Spaces: You are preparing to work in a confined space. It is important to ensure somebody knows you are entering the crawl space, is within reasonable earshot of the crawl space, and is prepared to call for assistance if something goes wrong. OSHA has strict requirements for working in confined spaces for good reasons.

For more information on safety in confined spaces, visit OSHA’s page on the subject.

Remove Insulation and Debris From the Crawl Space

Before you go directly after the mold, remove all unneeded materials and debris from the crawl space. This includes anything that will be in the way or needs to be removed anyway like insulation, old plastic sheeting, wood, old pipes, trash, and any other debris left in the crawl space. Heavier items, such as old cast iron drain pipes,  that cannot be removed should be moved out of the working areas as much as possible. Some bricks, stones or blocks can be left in the space for later use to weigh down plastic sheeting or other ground cover.

All fiberglass insulation should be removed from the space. This in and of itself can be a very large job, but is needed to do a sufficient job of cleaning. Over time, fiberglass insulation becomes soiled with mouse droppings and other contaminants, as well as mold spores that have accumulated between the fibers over time. You can drag the insulation out, as is, for disposal or bag it first. If you bag the insulation first, keep in mind the size of the hole the bag will need to fit through to get out. A typical, fully insulated crawl space could require 50-100 contractor size trash bags to empty the space of insulation. If your crawl space access is on the interior of your home, you will need to protect surfaces with plastic sheeting. Take plastic bags out through a near window if the entry door is far away.

Also remove any paper left on the floor joists from the insulation. This may require a fair amount of work if the installers used a lot of staples. Very small amounts of paper under staples are unlikely to cause any major issues and can be left in place.

For these reasons, we don’t recommend that you insulate crawl spaces with fiberglass insulation between floor joists. Insulation can hold moisture at the wood surface, right where you don’t want it.

Foam insulation, either rigid foam board or spray-on foam, can generally be left in place assuming there hasn’t been an adhesive failure. These types of insulation can be cleaned if needed on the surface and rarely support mold growth any deeper than the surface.

Clean the Floor Joists and Decking

Doing the actual cleaning is just going to take a lot of elbow grease and the right cleaner. Finding the right cleaner can take a little trial and error, and may depend upon your comfort level with different chemicals.

Start With Soap and Water

Starting with the safest and gentlest cleaner, create a solution of dish soap and water and put it in a spray bottle. Spray the solution on the moldy surface, and gently scrub it with a soft bristle brush. If the mold on the surface appears to go away with no underlying staining, you are in luck! You should be able to clean the entire space with soap, general cleaners like Simple Green, Dawn dish soap, or other general purpose surface cleaner. In these cases we recommend the use of percarbonate solutions like Oxiclean. The carbonate residue left behind can help prevent mold in the future and some stain removal and brightening of the wood will occur while cleaning.

The percarbonate solution we recommend is one cup of OxiClean (or equivalent brand) with one gallon of hot water. Some minor staining that may remain when you are completed can be bleached out later, so don’t worry if there are a few small areas that don’t appear to come completely clean.

A Stronger Cleaner

If there is still a significant amount of staining (like dark black spots) after the soap and water test, you’ll have to use a stronger cleaning solution. Many stronger chemicals for mold removal involve some amount of bleach. Some use peroxide, but we haven’t found a peroxide solution that is as effective as chlorine bleach based products to remove staining on wood.

While bleach is effective, it does come with added dangers, such as irritation to eyes, skin, and the respiratory system. Ideally, you would always start with a soap and water or percarbonate solution and only use a bleach based cleaning product or mixture on small areas afterward to clean up remaining stains. After cleaning, you can apply a solution of 1 cup of sodium carbonate to 1 gallon of hot water, or 1 cup of bleach to 1 gallon of hot water, to help prevent mold from coming back.

Safety Tip, Bleach is Dangerous: Using moderate to heavy amounts of bleach in a confined space can be an extreme respiratory hazard. Use a full face respirator with organic vapor cartridges, and follow our previous tip about ensuring somebody is nearby for help. Also, never mix bleach with other cleaners, as it can create deadly toxic gasses if mixed with the wrong substance. Bleach is a highly alkaline product that is commonly referred to as caustic. Caustic chemicals can burn the skin or cause irritation that will take some time to go away.

Finishing Touches

Once the cleaning is completed and you are happy with the overall cleanliness of the space, there are a few more things to consider.

Preventative Treatments

Treating the wood with a preventative could help you avoid this issue in the future. It isn’t a substitute for fixing the water issues, but it is an additional layer of protection. A mixture of sodium carbonate (washing soda), sodium bicarbonate (baking soda) and a little soap can be effective and inexpensive. Borate salts like boric acid, borax or Tim-Bor (sodium octaborate tetrahydrate) are also possible choices. Contact Indiana Mold Remediation to discuss available preventative measures.

Vapor Barrier or Encapsulation

A plastic vapor barrier is required by code in most areas of the country, and will likely be required if you are preparing the home for resale. An encapsulation system can go even further to protect your crawl space from the dangers of water and mold.

Drainage Systems

If your crawl space retains standing water after it rains, you need to repair your drainage system or install a new one. Most drainage is a matter of trenching and routing incoming water to a sump pit. This is also something you can do, but it is beyond the scope of this guide to discuss it.


Active ventilation helps to exchange air in the space and prevent moisture build up. Closing all crawlspace vents and actively drawing air from the crawlspace and sending it outside can create a negative pressure that helps draw conditioned air from the home into the crawlspace. This is a way to condition the space and prevent the build up of moisture in the crawl space air. There are reasons you may not want to do this, so if you are in doubt we recommend you contact us, or your local professional, for advice.

Need Some Help With Your Crawl Space Cleaning?

Whether you need a professional to do the work, or just some advice along the way, we're here to help. Reach out to Indiana Mold Remediation about your crawl space issues for a no-obligation 15 minute consultation at no cost.

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