NIOSH Mold and dampness assessment tool

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Until recently there were no detailed standards for assessment of mold and moisture intrusion in buildings. The first such standard was released by ASTM in 2014. The standard “ASTM D7338 – 14. Standard Guide for Assessment Of Fungal Growth in Buildings” describes minimum steps and procedures for collecting background information on the affected building, procedures for evaluating the potential for moisture infiltration or collection, and procedures for inspection for suspect fungal growth.

NIOSH mold assessment stepsNIOSH has now introduced an additional tool for mold and dampness assessment. The tool includes checklists and instructions to guide users through assessing rooms for mold and dampness, and then identifying the sources.

The NIOSH Mold and Dampness Assessment Tool has two versions – one for general buildings and the other one for schools. The tool has a four-step assessment cycle as well as a scoring scale that ranges from 0-3.

The four-step mold and dampness assessment tool

These are the 4 steps for mold and dampness assessment:

  1. Assess- Use the Mold and Dampness Assessment Tool in all rooms and areas of your building(s).
  2. Identify- Determine the source(s) of dampness or mold identified in STEP 1 by further investigating where the moisture is coming from.
  3. Repair & Remediate- Facilities staff or trained professionals should repair all identified sources of dampness and mold and remediate damaged areas following proper mold removal guidelines.
  4. REPEAT- Schedule regular building assessments to prevent new or worsening problems and repeat STEP 1.

Assessing and Scoring Damage

Assessing Damage
Three types of damage are assessed.

  1. Damage or Stains
    This refers to any water-related damage or stains identified per component. Damage could include peeling paint, efflorescence, rust, warping, and deteriorated or crumbling building materials. Stains could include discoloration caused by possible water leaks, flooding or condensation.
  2. Visible Mold
    Note if you see visible mold growth or suspect mold growth. Mold can include patches or spots that are colored differently than the
    underlying material (typically gray, brown, or black). Mold can appear
    fuzzy and can have a musty or earthy odor.
  3. Wet or Damp
    Note any areas of wetness or dampness that are visible. Wet or damp conditions could include visible signs of moisture, such as water beads or condensation, humidity, water leaks, or flooding.

Scoring for Mold

Scoring for mold growth in NIOSH Mold and dampness assessment tool is based on the size of all affected areas combined. Individual sizes of each affected area are added together to obtain a combined size. The scoring scale is as follows:
0 = No problem areas identified.
1 = The combined area of damage is the size of a standard sheet of paper (8½ inches X 11 inches) or smaller.
2 = The combined area of damage is greater than the size of a standard sheet of paper (8 1/2” x 11”) and less than the size of a standard interior door (32” x 80”).
3 = The combined area of damage is greater than the size of a standard interior door Interior door (32” x 80”).

According to NIOSH a score of 3 for Damage or Stains, Visible Mold, or Wet or Damp should trigger immediate attention to identify problem sources and to remediate. Similarly, a score of 3 for Mold Odor should trigger attention to identify areas of hidden mold.



  1. Dampness and Mold Assessment Tool for General Buildings
  2. Dampness and Mold Assessment Tool for School Buildings
  3. ASTM D7338 – 14. Standard Guide for Assessment of Fungal Growth in Buildings.
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Dr Jackson Kung'u
Dr. Jackson Kung’u is a Microbiologist who has specialized in the field of mycology (the study of moulds and yeasts). He is a member of the Mycological Society of America. He graduated from the University of Kent at Canterbury, UK, with a Masters degree in Fungal Technology and a PhD in Microbiology. He has published several research papers in international scientific journals. Jackson has analyzed thousands of mould samples from across Canada. He also regularly teaches a course on how to recognize mould, perform effective sampling and interpret laboratory results. Jackson provides how-to advice on mould and bacteria issues. Get more information about indoor mould and bacteria at
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