Wondering if that musty smell in your home or office is mold?

mold inspectors under a building in material hazard suits testing for mold

Mold Testing – Mold Inspection

Performing a mold inspection or mold testing in the Bay Area is important if there has been a leak or flooding in your building. There may be a “musty smell” emanating from part of the building. A thorough inspection and mold test can determine if there is an indoor source of mold.

Mold testing and mold air quality tests mix both art and science. An expert should not sell testing without a thorough moisture and mold inspection. Sometimes mold testing is not useful and may be a waste of money.

Other times assessments must include lab analysis in order to identify Stachybotrys (“toxic black mold”), from other types of mold or to determine if parts of a building have been cross-contaminated with mold spores. Mold testing is also used to determine if an area has been properly remediated and cleaned, an abbreviated survey known as “mold clearance testing.”


mold growing on building interior ceiling - mold testing San Francisco Bay Area

Any qualified environmental consultant or industrial hygienist will confirm that mold inspections are a top priority, especially in the Bay Area, where mold and moisture are prevalent. Using a flashlight, thermal imaging, a moisture meter, two eyes and a nose, a competent inspector can usually tell you whether mold is present. Often they can draw conclusions as to whether it is toxic. Sampling in the absence of a thorough moisture and mold inspection is not recommended, and the data collected from such sampling is missing necessary context.

Healthy Building Science advocates the following steps:

  1. A qualified, professional expert should provide a thorough moisture and mold inspection of the building.
  2. Formulate a hypothesis as to the presence of moisture, sources of moisture, and the extent of mold damage.
  3. Determine if sampling would add value to the mold assessment (if not, skip to #6).
  4. Develop a sampling plan to test the hypothesis.
  5. Sample and review data.
  6. Report findings from the inspection, hypothesis developed, sampling results, and conclusion for next steps.

If your mold inspector doesn’t offer a comprehensive moisture assessment, pushes a lot of testing, or does microbial testing and only shares the lab results without a clear interpretation of their meaning, they are not providing value or helping your cause. Do-it-yourself petri dish style mold testers are not recommended in the absence of a professional inspection.

Mold testing is useful for:

    1. Determining relative toxicity of mold species in the presence of symptoms or sensitive populations.
    2. Establishing a baseline prior to remediation.
    3. Determining the scope of contamination.
    4. Clearance testing after remediation to confirm the area is clean, and, last but not least,
    5. Peace of mind for those concerned.

    Testing Methods and Strategies for Mold

    Environmental consultants often perform a survey including some form of microbial lab analysis. When testing for any pollutant, there are myriad ways to collect samples to analyze in the lab.

    Some common testing methods are:


    • Airborne mold spore trap

      A known amount of air is drawn over an adhesive slide. The slide is analyzed by lab technicians who extrapolate a “spore per cubic meter” number for each sample. Spores are identified to the genus level, but not to the species level. Penicillium and Aspergillus cannot be distinguished between each other in this particular microscopic analysis. Comparing indoor and outdoor samples, we can draw conclusions about airborne spore counts in the building.

    • Bulk mold testing

      A tape lift, swab or bulk building material, such as a small sample of drywall, is analyzed through a microscope. This method has the same genus level id limitations as a spore trap.

    • Environmental Relative Moldiness Index (ERMI) or Polymerase Chain Reaction (PCR)

      This method utilizes microbial DNA analysis to identify mold to the species level, but relatively few species have been cataloged so this rapid testing method can miss a majority of molds present. Environmental doctors and naturopaths are familiar with this method and it has gained more traction in recent years.

    • Mold culturing

      Viable mold spores are sent to a testing lab and cultured. The spores are placed on Petri dishes with a selected growth medium, sufficient moisture is provided and temperatures are regulated simulating optimal growing conditions. Some spores may be present (and toxigenic and allergenic) but not viable and therefore do not grow and colonize. Mold colonies that do form are identified to the species level. This form of analysis takes longest of all options presented here and fewer testing labs offer this method.

    Survey Process for Water Damage and Mold Inspection

    Healthy Building Science will meet you onsite. We are courteous and considerate of your space and careful not to track in dirt and careful not to spread mold spores or cross-contaminate spaces. We prefer to inspect the whole building, and we take samples only if it will add value for our client. We email or mail our report and follow up with email or phone calls to answer outstanding questions.

    In some instances, HBS writes a Mold Remediation Protocol (MRP) outlining requirements for safe removal of mold from a building. Mold Remediation Protocols are detailed instructions including safety requirements and the scope of work for your specific project. Our MRPs are designed in accordance with industry accepted standards (IICRC S520 Mold Remediation Standard).

    Clearance testing involves sampling before and after remediation. Pre-mitigation samples quantify mold spore counts, identify particularly virulent species, and create a baseline for remediation. The post-mitigation “clearance” samples confirm if remediation was performed properly and the space was thoroughly cleaned before containment is removed.

    Bay Area Mold Testing Case Studies

    • Walnut Creek mold testing for a multi-family building in a retirement community
    • Santa Rosa mold inspection for a school
    • Fremont mold survey for a manufacturing facility
    • San Rafael mold expert for a product manufacturing and bottling facility
    • San Francisco mold consultant for a high-end custom home
    • Oakland commercial mold testing
    • San Francisco mold inspection for a school
    • San Jose mold inspection for a data center
    • Berkeley mold survey for a medical office building

    Mold Testing San Francisco Bay Area

    Healthy Building Science is an environmental consulting firm providing mold inspection services for commercial, residential, multi-family buildings, offices, industrial and manufacturing workplaces, hospitals and medical facilities, and single-family homes in the greater San Francisco Bay Area and Northern California. Cities we service include San Francisco, San Jose, Oakland, Sacramento, Santa Rosa, Hayward, Sunnyvale, Fremont, Concord, Salinas, Santa Clara, Berkeley, Vallejo, Fairfield, Antioch, Richmond, Daly City, San Rafael, San Mateo, Vacaville, San Leandro, and Livermore and Alameda County, Contra Costa County, Marin County, Napa County, San Mateo County, Santa Clara County, Solano County and Sonoma County.

    Call (415) 785-7986 or complete this form to discuss your mold testing needs.