Home Uncategorized Help! We Just Uncovered a LOT of Hidden Mold in Our Home!

Help! We Just Uncovered a LOT of Hidden Mold in Our Home!

by Catherine

How to Stop Mold and Mycotoxin Cross-Contamination Once Mold Has Been Exposed and/or Disturbed

Recently, I recieved the following email from a reader who found herself in the middle of a mold and mycotoxin cross-contamination nightmare after starting on demo for a home renovation:

Dear Catherine,

Thank you for your time and willingness to share your expertise. We are just getting started on this mold journey…Here is what was behind my vanity where I wash my face and brush my teeth. It is perhaps why my eyes have burned since January! Sadly, we didn’t really know and just had regular contractors doing the demo. No serious containment. I’m now trying to figure out the next step. Any advice on what we do from here? Also, did you consider hiring a company like SERVPRO to help with the cleaning process?

Before I share my answer, I need to tell you where I stand on any kind of indoor demo without containment, especially if you are mold sensitive–I DON’T THINK YOU SHOULD TAKE THAT KIND OF CHANCE WITH YOUR HEALTH. Setting up containment is not that time consuming, not that expensive, and not difficult enough to not do it, in my opinion.  Because my family is mold sensitized and we have already been taken out by a significant toxic mold exposure in our home, I am NOT willing to take chances these days. When it comes to work being done on our home that requires demo and opening up walls, ceilings, or ripping out building materials, we always set up proper containment around the area where we are doing the work before we begin. It is a non-negotiable precaution for us these days.

Lucky for me, my husband is a former builder, so when we are doing work on our home, big or small project, we, meaning he, is usually doing the work. That means, I am lucky on two counts: 1.) my husband is extremely handy and capable of building or fixing almost anything; and, 2.) when renovations or fixes are going on, I have complete control over how it is done from demo to rebuild. My control over the situation these days also includes proper containment before, during, and after the work. It took our health crisis to make me realize just how dangerous it can be to start on one of these “home improvement” jobs, uncover hidden water damage and/or mold growth, and not have the proper precautions in place. I have experienced enough health setbacks by now to know that another mold exposure, even a small one, can have catastrophic consequences on our health. Thus, the pain and expense of putting up containment prior to any kind of demo is worth it to me for what it could potentially save us health-wise (both physically and emotionally), if we didn’t.

Is Containment REALLY Necessary When There’s No Visible Mold?

(Note: I want to make sure everyone reading knows that this post is geared at people embarking on home projects with no KNOWN or suspected mold growth. This advice is for mold avoidance and mold maintenance to keep you and your family safe when you don’t expect mold. If you have had flooding, known leaks or water damage, or have visible mold growth, you need to call in certified mold remediation professionals to set up the containment, perform the demo, and clean and remediate the space.)

Did you see the picture at the beginning of this post?!!! Need I say more?

I know that to the non-“moldies” out there, I may seem totally off of my rocker and like I am creating a bunch of unnecessary work and precautions for nothing, but, given the damage that mold can do to your body, and given that 25% of the population has the HLA-DR gene that makes it difficult for them to recover from mold and other toxic exposures, and given just how many homes and buildings have hidden water damage (conservative estimates say over 50%), I think my decision to err on the side of caution makes me smart, rather than alarmist. I also think that from an indoor air quality perspective, employing the correct containment practices with any renovation or home improvement project can prevent dust and construction debris and airborne particulates from invading other areas of your home where they can be inhaled or swallowed, causing reactions, health problems, and/or long-term sickness. (Your environment is, afterall, more important than your genetics for your immune health.) Thus, for the purposes of maintaining a healthy home and a healthy body, I think the advice I have to share today is actually for anyone and everyone, not just mold sick or sensitized folks.

Why Disturbing or Uncovering Mold Without Containment Can Be Problematic

To illustrate why it is so important, especially if you are mold sensitive, to use containment inside your home if you plan on any kind of demo or renovations, I want to explain a little more about mold and what happens when mold is disturbed and uncovered in an indoor environment:

Mold spores are tiny structures produced by molds for reproduction purposes. They are so small that we can hardly see some of them even when magnified 400 times. One cubic meter of outdoor air may contain as many as 1,000,000 mold spores. The volume of air we inhale at rest is estimated at 10 liters per minute. Therefore, in an hour we could potentially inhale close to 600,000 spores.  To give you an idea of what these numbers look like in a “sick” indoor environment, the air in some “water-damaged buildings” has been shown to contain up to 1,000,000,000 spores per cubic meter of air. Thus, you can obviously see why living or working in such an environment will cause sickness and poor health outcomes for the population of people who are mold sensitive. You can also see how opening up a wall with a hidden leak that has significant mold growth can set hundreds of thousands of mold spores free into the surrounding air.

Now, in indoor environments, mold tends to grow on organic surfaces where it can find moisture, such as the drywall, wallpaper, carpet, baseboards, and heating, ventilation and air-conditioning systems (HVACs). As mold grows, a stage is reached when it produces spores. These spores can easily become airborne after drying out or if disturbed. This is why drying out a moldy area can sometimes be more dangerous then allowing it to stay wet, if proper containment is not in place, because millions of microscopic spores can be released and completely contaminate an indoor space very quickly. The spores are easily transported via the air, through ventilation systems, and on dust, dirt, people, animals, and belongings in the home.

If I Shouldn’t Disturb Mold, How Do I Get Rid of It?

When mold is remediated, it does not need to be killed, but, rather removed from the property with the least amount of disturbance as possible. Even when mold spores have been “killed,” say with an antimicrobial or antifungal, they can still be harmful, because they can still release spores and mycotoxins. It is therefore necessary to not only remove the mold, but to also ensure you are removing it with little to no spores left over at the end of the process. (I will get into how to do this in detail later in my response to the reader.) This means cutting out all affected building materials with a wide girth around the mold to make sure you are getting it all.  It also means employing HEPA vacuums, and physical cleaning techniques to keep the mold spores out of the circulating air as much as possible.

In addition, the longer mold grows on an item, the more it penetrates the item, eventually causing irreparable damage. You see, as mold grows, it grows in a 360-degree range, meaning that mold grows across the contents, away from the contents, and into the material of the contents. Mold literally invades its host. The longer mold has burrowed it’s way into a material, the less likely it is that you can fully remediate the spores. This is precisely why you want to remove all mold, not just kill or encapsulate it, and why it is difficult to remediate porous items that have been contaminated, even with microscopic mold spores.

Basic Containment for Home Improvements and Renovations

To account for the fact that there is always a possibility of finding hidden mold growth when you are opening up ceilings, demoing walls, removing and/or replacing anything tied to your plumbing, aka a water source, like your dishwasher, toilet, or sink, you can and should set up some very basic containment in your home to keep you and your family safe. Then, if, like the reader whose email I shared, you remove your bathroom vanity and find a horror show of black mold, you know that the space has been reasonably contained and sealed from the rest of your home. This gives you time to call in professionals to assess and further contain and seal the area,  and to get the area fixed and remediated without same magnitude of danger from exposure and the stress of not knowing how far the cross contamination has spread.

DIY Basic Containment Set-Up for Construction Projects

(Note on Negative Air: Normally, for mold remediation, the first thing that you would set up in a containment scenario is negative air pressure. The idea here is to exhaust the air from the contaminated space to the outside of the home. This controls the spread of mold spores. Since we are not containing known mold growth, this is not necessarily necessary. From a particulate standpoint, though, and to control construction dust and airborne particulates, I always like to set up negative air machines. You can do this by using an actual HEPA-filtered negative air machine–you can purchase one online or rent one from your local home improvement store–or by positioning a box fan in a 1/2-open window, so the side that blows faces the outside and the side that “sucks” faces inside. Use duct tape to attach a MERV 13 filter over the “sucking” side of the fan. Now you have created your own HEPA filter! If you do decide to use a negative air machine, you will need to route the air inside the space to the outside via flexible tubing or ducting.)


Painters (blue or non marring) tape preferably 2″ wide, Duct tape, or better Gorilla tape

Staple gun

6 mil clear plastic sheeting

 A zip wall tape zipper for building barriers

 Box cutter

Step ladder

1.) Designate your work space. When you select the work space, make sure that you have chosen enough room to work in and encompass the work to be performed.  A good rule of thumb, is to make it bigger than you think, and use common areas of entry and exit as the exterior barrier of the work space area.  Decide where your entry and exit to the work space containment area will be.  It is best if you can to use a door.  Try to be sure that you have a window in the room to the outside if possible. IF you do NOT have a window in your work space it is ok, but, if venting and negative pressure do need to come into play, it is much easier.

2.) Remove all personal belongings from the work space. You don’t want any personal belongings left in the contained area. This will help protect them from any potential exposures. If you cannot remove them, you will need to cover and seal them under the 6 mil plastic sheeting.

3.) Install physical barriers in the work area. This is most typically done with the use of heavy 6 mm plastic. The main goal when creating this physical barrier is to completely isolate the work area from any adjacent, non-affected areas. Depending on the layout, any doorways should be completely sealed with plastic. You will be creating a sealed “room” by hanging your plastic from ceiling to floor and sealing all seams and separations with tape. You can use your zippers to create a sealable entrance and exit from the space. Any flooring that is to remain after the work should also be covered with plastic and sealed.

4.) All HVAC systems or shared airways between other rooms should be taped or covered in plastic, and all electrical outlets and light fixtures should be covered as well. In essence, any area that could allow air communication between the work area and other non-affected areas should be properly sealed.

5.) Optional: Once the previous steps are completed, you can employ your negative pressure. As a result of this negative air pressure within the work space, any mold spores, dust or debris that become airborne are being controlled, preventing them from affecting the adjacent spaces and flushing them away from the indoor environment.

If you use basic containment and set up your workspace correctly, you will have little to no dust or debris enter the air in the rest of your home. This is especially true if you employ negative air pressure. You also don’t have to worry about dust and particulates getting into your HVAC system or ductwork to create future problems. You can finish your work, vacuum and clean the contained area, and take down your barriers without worries of cross contamination.

How to Mitigate the Damage of You DO Uncover Hidden Mold

Now that you have the basics of how to proactively control a potential hidden “mold situation” in your home, I also want to go over how I would control the damage in a case where hidden mold is uncovered and exposed. A perfect way to do that is to share my email response to the reader from the beginning of this post.

Here it is:

Oh, my! Ok, we need to get this controlled ASAP, so that your health doesn’t suffer more than it already has.

I have packed as much information as humanly possible in this email, so that you will have the information that you need to hopefully make your home safe again. First, if I seem extreme, please understand that in no way I am trying to overwhelm or scare you. I want to make sure you get this taken care of safely and correctly, so that you family can stay well and move on. If you take this step-by-step, you can do it right.

At this point, you definitely need to halt all construction. The following steps should be taken ASAP to ensure your continued health and safety now that all of that mold and microbial growth has been uncovered:

  1. Do not enter that area anymore, if possible. If you have to, only do so with proper personal protective gear. In my opinion, that should consist of no less a N95 respirator mask, a Tyvek suit, shoe covers, googles and gloves. That protective clothing should be bagged and kept outside of your home and should not be worn into “safe” areas. 
  2. Contain the area as much as possible with all of the exposed mold growth to mitigate the spread of the mold spores and mycotoxins. You should do this immediately. Purchase some 6 mm plastic sheeting from a home improvement store. Close the supply and return vents and cover them with plastic and seal with tape. Cover any light switches or outlets with plastic and seal with tape. Close doors into or out of that area. Tape the sheeting with double-sided tape over any doors into or out of that area. Seal the plastic at the bottom as well to not allow air to escape. The goal here is to put up temporary containment until professionals can do a better job and can begin the remediation process.
  3. Document EVERYTHING. Take pictures and have the inspectors and remediation company take pictures as they work. You might need these for insurance claims and to keep tabs on the work. This information can be invaluable down the road, so please document more than is needed.
  4. You know that you have a significant mold issue in that bathroom. Thus, testing of the bathroom is not necessary at this point to initiate remediation work with a certified and licensed mold remediation company. The containment and work needs to be started on this area ASAP. You need to find and hire a certified mold remediation company in your area to properly remove all moldy building materials and to clean and remediate the area to make it safe again. This company will also need to work with a plumber to fix the water issue that is causing the mold growth in the first place. You can go to the ACAC site to find a company that has the proper accreditations. They need to understand containment, personal protective equipment, safe demo and mold removal practices, cleaning, and be willing to work with an outside professional on clearance testing once the work is complete. 
  5. A certified and licensed mold or environmental inspector also needs to be employed to assess the extent of the contamination of the rest of your home. This person will need to do a visual inspection, air, bulk, dust, and mycotoxin sampling, and inspect and test your HVAC system and ductwork. The results of this testing will determine how extensive the cross contamination is. They will also be able to pinpoint additional sources and areas of mold growth. You can work with them to devise a plan of contents and air cleaning procedures to make the rest of your home safe. This person should NOT also perform remediation. That is a conflict of interest. This person is your helper, advisor, and advocate with the remediation company. The ACAC site is also a good place to start to locate one of these professionals. 
  6. Clearance testing must be done on the area where the mold was uncovered after all remediation and demo is complete, but BEFORE and rebuilding or construction begins, or containment is removed. This is imperative. Do not allow anything to be closed up, rebuilt, or containment to be removed until the area is tested and cleared as safe. The mold inspector NOT the remediation company should do the clearance testing. If it does not pass, they must reclean and retest until it does.

Here are my additional notes and thoughts about best practices and things that you need to know to get this done right.

  • If the mold/environmental inspector finds high levels of mold spores and or mycotoxins in the rest of the home, the chances are very high that it has gotten into your HVAC system. Cut out a piece of the filter and have it tested. My experience with this is that the furnace or air handler will need to be replaced for the remediation to be successful if it is contaminated. The ductwork will also have to be replaced if it is flex duct. Flex duct cannot be cleaned. If the ductwork is metal, it can be HEPA vacuumed and cleaned successfully with EC3, or a non-toxic cleaner like peroxide. If this is the case, all carpets will need to be removed and replaced or properly cleaned. Belongings will also need to be sorted and cleaned or disposed of. HERE is a post that you may find helpful about that. 
  • I would go ahead and start being proactive in the rest of the home by doing things like:
      • Washing all clothing, bedding, and anything else that can be washed in the hottest water those things can handle with EC3 Laundry Additive (at least 2 ounces for a medium load) and 1 cup of Borax per load. Allow each load to soak for at least an hour after agitating before the cycle is allowed to complete;
      • HEPA vacuuming and then fogging all other areas of the home with EC3. This is a Band Aid approach, but will control cross contamination and significantly mitigate the damage.
  • If fogging is part of the remediation solution (and I believe it should be), it should occur after all demo and removal. It should be to bring the air counts down, so that the space can then be HEPA vacuumed and wiped down. I would only allow fogging with a safe botanical, like EC3. If it is a biocide, you do not want it sprayed into your home. They should also not be using ozone.

I hope I haven’t overwhelmed you with too much information. I sincerely think that if you jump all over this, it is VERY fixable and you can ensure that your family stays safe and healthy. Good luck and don’t hesitate to reach out to me with additional questions.



Questions? Comments? Ideas? I love hearing from you. Comment below or email me at catherine@moldfreeliving.com.


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