Identifying Mold

DIY Mold Inspection: Determining the Scope of Mold Problems on Drywall.

Cesar Collado
October 21, 2021

Reading Time: 7 minutes

​Do You Have an Isolated Mold Problem or a Systemic Infestation?

When someone in your family suffers from mold sensitivity, severe chronic illness, or is immunocompromised, quick determination of the magnitude of a mold problem is critical to fixing the problem and avoiding health consequences. Ignoring the issue can result in debilitating health symptoms and risk progressive chronic illness.

Mold spores exist everywhere on earth, including in your home air.  However, it requires a water source and food to reproduce rapidly.  This article is not about eliminating the presence of mold in any home.  It focuses on clearly identifiable mold colonies on walls or ceilings.  Is the mold cleanable as a DIY project? Is it significant enough to assume you may have a systemic mold issue with potential to contaminate an entire home?  If you can see or smell mold, it is likely a significant mold issue.

This article specifically addresses visual mold on walls and ceilings due to water intrusion.   How do you determine whether the problem is isolated and potentially a DIY project or systemic where a mold professional is required to ensure safety and avoid further home contamination? Isolated mold problems can often become systemic problems when the mold is disturbed and mold spores and/or mycotoxins are then released into the home ventilation system where the home air is contaminated by mold spores and/or toxins.

The first rule of any DIY inspection is “when you identify mold, you must find the moisture source and have it repaired immediately.”  Any repairs made without addressing the moisture source will result in mold returning rather rapidly. If the home has flooding, a significant leak, or water damage, it should be assessed by a licensed mold specialist. Unfortunately, an isolated mold problem can become systemic when destruction of a wall or ceiling is done without any containment.  Containment involves using plastic and tape to trap the mold spores in the area of the mold issue.

Dry Wall Repairs

Wet drywall reveals itself well with discoloration, paint peeling, and bubbling.  If the drywall has been wet for a significant period of time (a few days or longer), it most likely will need to be removed and replaced.  Drywall absorbs water and is composed of organic materials including cellulose, making it an ideal environment for mold to flourish.  In addition, any insulation that has been wet and contaminated will likely grow mold.  Therefore, this section of insulation should be replaced as well. The EPA recommends DIY repairs be limited to areas less than 10 square feet or a 3’ x 3’ patch.

When you or someone sees a single small dot of mold, there is orders of magnitude greater numbers of spores in the colony below the surface.  Visual mold is merely the “tip of the iceberg.”  Over 250,000 spores can fit on a pinhead. The Journal of Property Management reports that one square inch of drywall can contain up to 10,000,000 spores.  Because of this, it is best to utilize safety precautions or hire a professional if you are sensitive to mold or chemicals.

After identification of the source of moisture, fixing the moisture problem is the top priority This often involves the services of a licensed plumber or general contractor.  Unfortunately, many people will fix the leakage and assume the building materials will dry.  In a dry climate, that may be possible if the leak has been there less than 48 hours.  The majority of drywall water damage issues require commercial dryers to dry the area for numerous hours.  You can often rent these at larger hardware stores (e.g. – Home Depot or Lowe’s).

It is most likely that the leak may take days, weeks, or months to discover, whether by smell or visually discovered dampness in a wall, floor, carpet, or ceiling.  At some point, it can become too late to salvage.  Dried mold can become dormant in drywall and be relatively harmless if not disturbed.  It will resume growing at an increased rate if it becomes wet again.

It is not practical to suggest all drywall that gets wet needs to be replaced.  In fact, every home with drywall that exists has likely experienced moisture during the construction process or because of bad weather, humidity, or leaks. If damp areas dry quickly and mold becomes dormant on the inside of the wall cavity, it often offers no direct threat to occupants as the mold is likely dormant and sealed inside the wall.  In several cases, it may be best to leave walls that are dry alone.  You shouldn’t risk mold exposure by destruction to identify mold in a wall that is not causing health issues.  Once again, mold is ubiquitous on this planet.  That includes every home.  The moisture combined with cellulose or organic material is the safety issue.

Attempting to repair too large of a mold area can result in the unintentional release and distribution of both mold spores and mycotoxins that can make you and others severely ill.   Drywall absorbs and retains water.  Mycotoxin producing molds, such as aspergillus, penicillium and stachybotrys commonly grow in damp drywall. Mycotoxins are the secondary metabolites of species  and are potent chemical toxins. When removing any drywall, it is important that safety precautions be taken to protect eyes (goggles), respiratory pathway (N95 or P100 mask/respirator), and hands (latex or nitrile gloves). The sections of drywall removed must be carefully contained in plastic bags and disposed of outside the home.

Properly cleaning the entire area of the interior and exterior of the wall is essential.  There are numerous chemical products that kill mold.  However, mold sensitive people are often chemically sensitive.  If chemical products are used to kill the mold, the home may continue to be toxic until all the chemicals evaporate or “off gas” over time.

Mold remediation by someone who is chronically ill is a very ambitious DIY project and it is recommended that they hire a mold damage specialist (i.e. – mold remediator) to make these repairs.  These professionals are skilled in the use of equipment to dehumidify, dry, and clean and fog the area with proper products. They also employ safety precautions to ensure the drying and containment of the mold to avoid contamination of the rest of the home when removing.

There are several Haven cleaning and fogging products that are non-toxic to clean and remove the mold.    To learn more, click HERE.   For raw building materials the BioBalance Peroxide Kit is a great treatment solution.

Systemic Infestation

If you are unsure of the magnitude of the mold issue, it is better to play it safe and assume the issue could become systemic to your home.  There are many ways a mold problem can be systemic or complex:

  • The section of mold exceeds what can be safely removed.
  • The area has been wet for a lengthy period.
  • Toilet or sewage issues combine water damage with additional bacterial and fungal contamination.
  • Mold can be spread if moldy furniture, carpet, compost, etc. is carried carelessly through a home without being contained. Just carrying a moldy item through the home once can spread the mold and mycotoxins.
  • When Humidity is the source of moisture, regular dust can become the food component for mold reproduction, When the HVAC system is contaminated. This often occurs in the system where water condensation or humidity is mixed with dust or insulation.  Once mold enters the HVAC system, the ventilation will spread mold spores throughout the home.  An HVAC professional can clean inside the system.  Ductwork professionals can clean the interior ducts as well.



  • Even cement can be the source of moisture. This occurs when exterior water management causes water to settle on the exterior of the home.  Water can travel through cement across a wall or floor. The moisture combined with regular dust will provide an environment for mold to reproduce. Crawlspaces or basements are common sources of mold problems.  These areas in a home are often unfinished or exist without insulation, air conditioning, and interior finishing.  Dust often accumulates and humidity or wetness from outside is common.  There is a physical science phenomenon called the stacking effect that explains how mold contamination will spread as warm air rises upward though the home.

As with any isolated problem, the first issue to address is identifying the source of the moisture and have that fixed.   Systemic mold may require addressing the humidity in parts of the home or the entire home.  Dehumidification is the solution in these cases. Any repairs made without addressing high humidity will result in mold returning rather rapidly. Dehumidifiers exist in portable room units or whole house units that can be installed by an HVAC professional.

DIY Hot Fogging

There is a DIY systemic treatment that can be done in your home with minor, short-term inconveniences, but at an affordable price.  DIY fogging allows you to fill the entire home (cubic feet of space) in your home.  The fog contains a natural, botanical blend that can saturate your living space.  The fog will disseminate and evaporate over time.   It is recommended to avoid the home for a 12-hour period after treatment, as floors can become slick.  One additional benefit from fogging is that the fog will help identify leaks in the home visually, as fog pours out of unsealed areas of the home during teatment.

You can learn more about DIY Fogging  HERE.  If you would like to learn more about the science and safety of fogging, you can read this two-part article on

The Case for Fogging Part 1 and Part 2.

The fogger will fill the entire volume of the rooms, house, or crawlspace, etc. with positive pressure so that it will penetrate open cabinets and cover household furnishings and furniture.  It will take up to 12 hours to allow the fog to evaporate.  The denser the fog, the more penetration into crevices and hard to reach places.

Following fogging, it is best to thoroughly wipe or vacuum all vertical and horizontal surfaces with a wet wipe or with a HEPA vacuum to ensure mold and mycotoxin particles and debris are removed and not recirculated into the room.