How To Test Your House For Mold: Various Mold Testing

How To Test Your House For Mold

Indoor mold can be a serious issue in homes and buildings, leading to potential health problems and damage to structures. Testing your home for mold is important to identify if high levels of mold growth are present. This guide will provide key information on mold testing, the types of tests available, how to conduct them, and how to interpret the results.

What Is Mold and Why Test for It?

Mold is a type of microscopic fungus that grows in damp, warm environments. While mold spores are ever-present in indoor and outdoor air, excess moisture allows mold colonies to grow inside buildings. According to the EPA, there are over 100,000 species of mold.

Exposure to high levels of mold and mildew can cause a variety of health issues including allergic reactions, asthma attacks, irritation to the eyes/nose/throat, headaches, and other problems in sensitive individuals. In addition, mold can eventually damage building materials through its growth.

Testing is the best way to identify if your home has a mold problem. Both visual inspection and mold testing kits can help determine the location, type, and extent of indoor mold growth.

Signs of a Potential Mold Problem

Before conducting mold testing, it helps to visually inspect your home for common signs of mold. Be on the lookout for:

  • Visible mold growth – Look for fuzzy or slimy black, green, or white patches on walls, floors, ceilings, wood, and other surfaces. Mold can look like mildew or stain areas as well.
  • Musty odors – Notice any areas that smell moldy, stale, earthy or like mildew. The scent may come and go.
  • Excess moisture – Inspect for water leaks, high humidity, condensation issues, or flooding prone areas. This moisture enables mold to thrive.
  • Health issues – Take note if your health seems to worsen while in the home, especially allergy, asthma, or other respiratory problems. Headaches, fatigue, and irritated eyes/throat when home could also indicate an indoor air quality issue like mold.

If you spot these warning signs, then mold testing is definitely recommended. Even if no visible mold is present, testing can identify hidden mold issues.

Overview of Mold Testing Methods

There are a few main options for testing your home for mold:

  • Visual inspection – A mold assessment professional thoroughly inspects your home visually, identifies areas of visible mold growth, checks moisture issues, and looks for signs pointing to hidden mold problems.
  • Air testing – Air samples are collected and analyzed in a lab to identify spores and mold types present in your indoor air.
  • Surface testing – Samples are taken from visibly moldy areas or wall cavities to analyze mold types present and contamination levels.
  • DIY mold test kits – Self-administered kits collect air or surface samples that you then send into a lab for analysis.

The best approach often involves a combination of visual inspection and actual mold testing to gauge issues. Professional testing provides the most accurate look at potential mold hazards while DIY kits offer an affordable starting point. We’ll now explore these testing methods further.

Table 1: Overview of Mold Testing Approaches

Testing MethodHow It WorksProsCons
Professional Visual InspectionA trained mold assessor thoroughly examines your home to identify visible mold and signs of moisture/leak issues that may facilitate hidden mold growth.Expert identification of trouble spots; Checks for hidden concernsDoesn’t always test actual mold levels
Professional Air TestingUsing specialized equipment, a technician collects air samples that are then analyzed in a microbiology lab facility to identify mold types and spore levels.Detects types of mold present; Identifies issues even when mold is not visibleMore expensive; Requires a site visit
Professional Surface TestingThe inspector swabs visibly moldy areas and wall cavities, collecting samples that are analyzed in a lab to specify mold types and contamination levels.Identifies specific mold species present; Checks hidden areasCosts more than DIY testing
DIY Mold Test KitsSelf-administered kits allow homeowners to collect and submit air or surface samples to a lab for analysis of mold types and spore quantities detected.Affordable; Easy to useCan miss hidden mold if not also doing visual inspection

Professional Mold Inspection and Testing

Hiring an experienced mold assessor to test your home is the most thorough approach. Professionals have specialized devices to conduct air testing. They also have the expertise to pinpoint hidden trouble areas that might contain mold.

Assessors check key aspects like:

  • Visible mold growth
  • Musty odors
  • Damp areas and moisture issues
  • Past water damage and leaks
  • HVAC and vent system contamination
  • Wall cavities and attic spaces for hidden mold
  • Crawl spaces and basements prone to moisture

They can conduct both air testing to measure mold spore types and levels as well as swab tests to specify the mold species present on building materials and in wall cavities.

Various methods used in professional mold testing include:

Air Samples:

  • Spore trap testing – Inspectors use a Burkard or Allergenco spore trap to detect airborne mold spores. Air is collected and then sent to a lab for analysis under a microscope.
  • Viable mold testing – An Air-O-Cell or BioPump collector is used to gather mold spores that are still viable. The samples culture any mold present to identify genus and species.

Surface Testing:

  • Tape lift or bulk samples – The mold assessor tapes over visibly contaminated surface areas then sends the samples to a mycology lab. Culturing identifies mold type.
  • Dust sampling – Dust is collected from surfaces or air vents to test for mold spores and mycotoxins present.

Professional mold testing provides detailed results specifying the exact mold species found at your home and the concentration levels. It also identifies hidden mold issues you might otherwise miss. This allows for a targeted mold remediation approach.

Testing costs $300 to $600 on average depending on the size of your home and extent of the mold problem. Larger homes or those with more visible mold issues might fall at the higher end.

DIY Mold Test Kits

For homeowners who can’t afford professional testing upfront, DIY mold test kits provide an affordable way to get initial results. These kits walk you through the process of collecting samples at home that you then mail to a mycology lab for analysis. DIY kits available include:

  • Indoor air testing
  • Surface testing
  • HVAC and duct testing
  • Drinking water testing

Most air testing kits use an Air-O-Cell cassette or petri dish with agar gel to sample mold spores floating in your indoor air. Surface testing kits come with swabs, slides, and tape lifts to take samples from visibly moldy areas.

The DIY mold testing steps generally include:

  1. Select room(s) where you suspect mold issues based on visible growth, musty odors, moisture, or health symptoms there.
  2. Follow kit instructions carefully to collect the air or surface samples. Take photos of any visibly moldy areas tested.
  3. Fill out the submission form with info on rooms tested and symptoms occurring.
  4. Mail everything back in the provided packaging to the mycology lab.
  5. In 1-3 days, mold testing results are emailed detailing spore types and levels found. A professional interprets what the mold test results mean.

DIY kits range from $30 to $150 depending on the lab used and type of testing performed:

  • Air testing – $40 to $99
  • Surface testing – $30 to $70
  • Combination testing – $60 to $150

While DIY testing kits offer affordable preliminary results to identify a potential larger issue, they have some disadvantages compared to professional testing:

  • You may miss hidden mold growth areas
  • Homeowners make mistakes not following procedures
  • DIY tests identify genus but not species of mold
  • A professional visual inspection isn’t included

If your DIY test results come back showing elevated mold spore levels, it is smart to follow up with a professional mold inspector. They can identify specific remediation needs and check for any hidden infestation areas in your home.

Interpreting Your Mold Test Results

Once mold testing sampling is complete, the samples are analyzed under a microscope at the lab facility. The results should specify:

  • Types of mold spores detected
  • Concentration levels or spore counts
  • Comparison to standards for indoor and outdoor mold levels

Species identified usually fall into groups like Aspergillus, Cladosporium, Penicillium, Stachybotrys, and various allergenic mushroom molds. Let’s look at what elevated levels of common molds signify:

Aspergillus: A mold genus with many allergenic and pathogenic species. Overgrowths indoors are usually from excess moisture or water damage. Some types create mycotoxins.

Stachybotrys (black mold): Produces mycotoxins detrimental to health. Indicates very wet conditions and significant water damage. Difficult to eradicate without mold professionals.

Cladosporium: One of the most abundant outdoor and indoor molds. Causes allergies and triggers asthma but doesn’t damage buildings as severely as some mold types. Still requires moisture source remediation.

Chaetomium: Found in very wet, rotten wood indoors. Creates health-impacting mycotoxins that require hazard containment protocols during remediation.

Any presence of dangerous mold species above background outdoor levels necessitates professional mold remediation. Let’s look at typical standards used to interpret test results:

Indoor Mold Guidelines

  • Total spore levels: <500 spores/cubic meter
  • Individual allergenic spore species: <100 spore count

Outdoor Mold Baselines

  • Cladosporium spores: 1,000 to over 100,000 spores/cubic meter depending on climate
  • Basidiospores: Vary by season from <100 to 1,000+ per cubic meter

Indoor mold spore counts significantly above outdoor baselines signal an excess moisture and mold growth problem inside. Symptoms in your home’s occupants can also help gauge appropriate mold levels relative to personal health reactions.

Notes on the mold types and concentrations found in your home enable mold removal experts to address the most hazardous areas first. Testing identifies areas harboring particularly problematic mold species. Stopping further moisture issues also prevents future mold growth.

Table 2: Summary of How to Interpret Common Mold Test Results

Mold Types DetectedLevels FoundWhat This Typically Means
Aspergillus, Penicillium1,000+ count/m3 or a 10 times increase above outdoor levelsAllergic potential; Possible pathogenic risk for vulnerable individuals
Stachybotrys (black mold) ChaetomiumAny amount 10+ spores/m3Serious moisture issue; Contains pathogenic and allergenic mold species producing mycotoxins
Cladosporium, other common molds10-100+ spore count/m3Mold growth from excess dampness present; Allergy/asthma triggers
No pathogen moldsVariety of spores in low to moderate concentrationsNormal outdoor molds also found indoors; No hazardous mold growth

Next Steps If You Have a Mold Problem

Once mold testing confirms a mold issue in your home, professional mold remediation is required to fully address the problem. Mold growth will only worsen without fixing underlying moisture issues first.

Typical mold remediation steps include:

  • Identifying and stopping all water leaks or dampness allowing mold colonies to thrive. This might require repairs to leaks from plumbing, roofs, foundations and more.
  • Containing and removing contaminated porous materials like drywall and insulation harboring mold growth. Non-porous surfaces may be scrubbed down and sanitized.
  • Treating remaining traces of mold and mold roots through fogging or application of antimicrobial chemical solutions.
  • Repeating testing to check if airborne spore levels have lowered to acceptable indoor levels confirming remediation success.
  • If mold issues are due to home construction defects or leaks from adjacent units, legal intervention with your builder or strata corporation might be eventual necessities as well.

In moderate to severe mold overgrowth cases, specialized mold removal companies should carry out remediation. They have extensive experience addressing dangerous mold types like black mold in a thorough and safe manner. Trying do-it-yourself mold removal often backfires or fails to fully eliminate the health hazards.

Let’s explore top reasons to hire pros for mold remediation and key aspects to look for when choosing a qualified mold company.

Why Hire a Professional Mold Remediation Contractor?

Mold growth over 10 square feet in size, a black mold presence, or severe health impacts already occurring are all signs you need professional mold remediation. Additionally, the following factors make DIY mold removal risky and likely to fail:

  • Hazardous mold types – Black mold, Chaetomium, and Aspergillus species contain mycotoxins harmful to health during spore releases in removal work. Special HEPA vacuuming and protective setups are required.
  • Wrong methods used – Bleach, vinegar, baking soda, hydrogen peroxide, and foggers do NOT completely eliminate mold. They address surface mold temporarily yet allow problems to persist and worsen.
  • Growth behind walls – You need contractor access and knowledge to remediate mold inside ceilings, wall voids, HVAC systems, attics, foundations, and more inaccessible areas.
  • Insurance coverage – Most insurance policies only cover professional mold remediation meeting industry standards, not do-it-yourself repairs.

Leave mold removal to the professionals in all but isolated small-scale cases. Yet choosing an experienced, certified mold company still proves critical so that the job achieves clearance testing standards.

Choosing a Mold Remediation Contractor

The Institute of Inspection, Cleaning, and Restoration (IICRC) provides mold remediation company certifications as a sign they employ proven methods meeting government safety standards. Top mold contractors should feature:

  • IICRC Certification – Companies hold an Applied Microbial Remediation Technician or IICRC Mold Removal Specialist certification.
  • Good Reputation – Check online reviews and testimonials to ensure quality remediation service history.
  • Proper Communication – The mold contractor thoroughly explains their complete mold removal process so you understand what will be done.
  • Clear Pricing – Get a detailed quote in writing covering all projected remediation work costs, with no surprise add-ons later allowed.
  • Post-Remediation Testing – The company conducts clearance testing after finishing mold removal work to confirm indoor mold levels lowered back to safe standards under 1,000 spores/m3.

Avoid any contractors that recommend simply painting over visible mold or applying unproven remedies. This risks occupant health and allows the underlying problem to worsen.

With the right remediation company addressing all moisture and mold issues fully, you can rest assured your home will be healthy and free of residual mold health hazards for your family.

Frequently Asked Questions About Mold Testing

Below we summarize answers to common questions homeowners have on checking their house for mold:

Can I detect mold without professional testing?

Relying only on visual inspection risks missing hidden mold growth. But it offers a starting point before paying for tests. Pay attention to areas with moisture problems, musty smells, or health issues to guide where testing focuses.

What DIY test kits work best?

For affordability, DIY air testing kits or mold swab kits effectively reveal preliminary results. Order them for rooms with current dampness, plumbing leaks, visible mold, or mysterious symptoms occurring.

How accurate are DIY mold test kits?

DIY kits effectively detect spore types and approximate levels. But species identification isn’t as specialized as lab methods pros use. False negatives also happen if sampling the wrong locations. Have an inspector double check for hidden infestation sites.

Can I just test one room or area of my home?

Start with rooms that have moisture issues, visible mold, or health reactions to limit costs. However, a full inspection and testing assesses all problematic zones, including secret mold behind walls and under materials.

Should I test annually for mold?

Generally only retest after major water damage repairs or if unexplained illness develops. Still, protect against mold year-round via moisture control, quick leak repairs, ventilation improvements, and cleaning mold prone HVAC systems.

Will testing locate all the mold in my house?

The best identification comes from combined professional visual inspection, air testing, and surface/wall cavity sampling. However, even the most extensive approach may miss some hidden mold locations. Ongoing vigilance for moisture helps avoid new outbreaks.


Regular testing gives insight into whether your home currently harbors hazardous mold growth and helps prevent more serious infestations. Look into both professional quantitative testing methods and affordable DIY mold inspection kits to start.

Ideally combine visual inspections to locate dampness and leaks enabling mold along with spore level lab results from air testing. This identifies the exact problem areas and species present so mold removal professionals succeed on their first try.

Stop moisture issues early before molds spread and cause health issues. Seek contractors for confirmed medium to large infestations to ensure complete elimination. Then you can breathe easy knowing your house stands clean and free of lingering mold hazards.

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