Remove, Don’t Kill Mould – Part 2 – Contents

Simply put moisture = mould. You first have to stop the moisture problem that’s causing the mould growth to begin with. Fix the leak, repair the roof, stop the condensation build up etc. Without this step mould will continue to reappear. This step also includes drying of all water damaged materials

If porous buldings materials are water-damaged and/or mouldy they will need to be removed and disposed of safely, using containment that can include plastic sheeting, negative air pressure and HEPA air scrubbers. These materials may need to be replaced, generally after the remediation process.

Porous materials include gypsum wallboard (drywall), ceiling tiles, exposed particleboard/MDF.

Semi-porous and non-porous materials such as solid wood, vinyl, floor tiles, cement and more may need special remediation techniques to physically remove the mould such as wire brushing, air blowing, freezing etc.

This process is for all surfaces – ceilings, walls, floors and cupboards/wardrobes – except carpets, which is a whole other blog post. Make sure surfaces are fully dry before going to the next stage.

a) HEPA vacuum surfaces (if surfaces have visible dust and vacuum can be ducted outside)

• Once upon a time there was a method called the HEPA sandwich that involved HEPA vacuuming of all surfaces, damp wiping, then a second HEPA vacuuming. This is no longer recommended and in fact HEPA vacuuming is only recommended if it can be ducted outside, so to reduce cross contamination. This is because HEPA does not trap the smallest fragments (< 0.3 microns) and its poor performance with electrically charged particles. From the Surviving Mold IEP panel:

• HEPA vacuums are known to perform poorly with small electrically charged particles; HEPA must not be used to clean surfaces after wiping. Surfaces should only be vacuumed if they have visible dust that can’t otherwise be moved with compressed air outdoors (example: furniture) or in a containment area within the capture zone of a HEPA air scrubber vented to the exterior.

b) Damp wiping using mild detergent plus water and microfibre cloths

• The aim here is to use a mild surfactant that, one that doesn’t leave a residue, to physically remove mould from surfaces. This could be castile soap and water, or dish wash liquid and water. Change the cloths regularly and don’t wipe back and forth or in circles, wipe in one direction.
• For mould on grouting use a grout brush
• Mouldy caulking may need to be removed and replaced

c) Antimicrobial damp wiping (optional)

• If you have, or suspect, bacterial contamination this is where you can use an antimicrobial/biocide. Ideally use isopropyl alcohol or ethanol (wood grain alcohol) diluted, 10% alcohol to 90% water. Some remediatiors may suggest vinegar (80% vinegar, 20% water), hydrogen peroxide, Napisan (1 cup to 6L), or quats at this step.

d) Borax fogging (optional)

• The remediator Greg Weatherman who co-authored the consensus statement and has written chapters in Dr. Shoemaker’s books Mold Warriors (2005) and Surviving Mold (2010) has developed a borax fogging solution, AeroSolver, that can trap ultrafine particles down to 0.01 microns in size. The AeroSolver is fogged in a building, using protective clothing, then dry wiped.

Best practice is for both the remediator and IEP to retest. There’s a couple of catches here; the majority of professionals will re-test using a combination of tape lifts and air sampling not ERMI/HERTSMI-2 and if they/you go that route you’ll have to wait 3-4 weeks for enough dust to collect on surfaces using the Swiffer collection method.

IICRC S520 says numerous times that removal of mould, rather than killing, is required in mold remediation, e.g.

5.8.1 Chemicals (Antimicrobials and Biocides)

Source removal of mold contamination should always be the primary means of remediation. Indiscriminate use of antimicrobials, coatings, sealants, and cleaning chemicals is not recommended.

Killing or suppressing mold growth will not address the adverse health effects caused by other microbial components such as endotoxins, exotoxins, beta glucans and mannans, among others. It is folly to advocate use of antimicrobial compounds as the “remedial solution” when the inflammagens, toxins and antigens are still present even if the mold itself is “dead.” Removing all toxigens and inflammagens, not simply focusing on killing what is or isn’t alive, is the only route to successful remediation.

Hope, J. (2013). A Review of the Mechanism of Injury and Treatment Approaches for Illness Resulting from Exposure to Water-Damaged Buildings, Mold, and Mycotoxins. The Scientific World Journal
Volume 2013 (2013), Article ID 767482. Link:

A common misperception is that killing mold, which is a relatively easy task, eliminates risk from contaminated environments or items. Unfortunately, this does little to decrease the risk as nonviable fungal spores, fragments, and mycotoxins remain present and, due to their structure, such as with an epoxide ring, [117] they can be extremely difficult to destroy.

While some agencies including the CDC advocate the use of bleach, the EPA in their A Brief Guide to Mold, Moisture, and Your Home in 2016, displayed more common sense:

Biocides are substances that can destroy living organisms. The use of a chemical or biocide that kills organisms such as mold (chlorine bleach, for example) is not recommended as a routine practice during mold cleanup…Dead mold may still cause allergic reactions in some people, so it is not enough to simply kill the mold, it must also be removed.

(but then talk about bleach being used in certain circumstances)

Occupational Safety and Health Administration (OSHA) in Mold Facts (2005) / Quick Card (2013):

Place mold damaged materials in a plastic bag and discard.
Clean mold off hard surfaces and other nonporous materials with detergent and water, and dry completely.

(but they too then go and and suggest disinfecting with bleach)

Guidelines on Assessment and Remediation of Fungi in Indoor Environments (2008):

Cleaning should be done using a soap or detergent solution. Use the gentlest cleaning method that effectively removes the mold to limit dust generation…Disinfectants are seldom needed to perform an effective remediation because removal of fungal growth remains the most effective way to prevent exposure.