Jan 25
Should I Have a Moisture & Mold Evaluation Before Buying a Home?

The answer to this question is "Yes," as I'll explain in detail below.  Mold can adversely affect your health, especially sensitive individuals and asthmatics.  It can be hidden within your home, costly to remove, and difficult to correct the moisture source.  Home inspectors, realtors, and general contractors are not mold experts, and do not possess the expertise and training required to identify potential mold issues.

 01 Home For Sale.jpg

I advise all home buyers to invest in both a home inspection and a moisture and mold evaluation before purchasing a home.  This is particularly important if suspected moisture issues exist or the home exterior consists of stucco siding.  This advice also holds true for existing homeowners and renters.

 02 Mold Inspection.jpg

Mold growth occurs normally in the outdoor environment, helping to break down dead organic matter from plants and animals.  We inhale mold spores every day with little to no adverse effects whatsoever.  When mold grows indoors, these conditions often change for the worse.  Indoors, the mold growth and its airborne mold spores are inhaled in much greater concentrations due to the confines of the environment.  This can lead to adverse health effects.


Molds and mold spores are fungi that can be found both indoors and outdoors.  No one knows how many species of fungi exist, but estimates range from tens of thousands to perhaps three hundred thousand or more.  Molds grow best in warm, damp, and humid conditions, and spread by producing spores.  Mold spores can survive harsh environmental conditions.  They can be reduced indoors by routine cleaning and filtering the air.  They are temporarily reduced outdoors during precipitation (i.e. rain, snow).  Without mold, dead plant and animal matter would never decay and continuously accumulate.  In order for mold to thrive, it requires food, the right temperature range, and most importantly moisture.  Mildew found in a shower/tub enclosure is also a form of mold/fungi that is typically caused by condensation on surfaces, which can be cleaned with standard household cleaners.

 03 Penicillium Mold Closeup.jpg

Molds and their spores commonly found indoors as a result of moisture issues include Chaetomium, Cladosporium, Penicillium & Aspergillus-types, and Stachybotrys-types.  Stachybotrys is commonly referred to as toxic black mold, in big wavy letters, by the media and news outlets.  Stachybotrys molds are typically indicative of a chronic moisture problem (i.e. basement water infiltration, plumbing leak).


Some people are more sensitive to molds than others.  For these people, exposure to molds can cause symptoms such as nasal stuffiness, eye irritation, wheezing, headaches, or skin irritation.  Some people, such as those with serious allergies to molds, may have more severe reactions.  Severe reactions may include fever and shortness of breath.  Some people with chronic lung illnesses, such as obstructive lung disease, may develop mold infections in their lungs.


Mold's purpose is to break down dead organic matter.  To ensure its survival, mold growth releases mold spores that settle onto possible food sources.  This is continuously happening outdoors, so mold spores are everywhere.  They get into our homes through windows, doors, and gaps and cracks in the building envelope, infiltrating attics, basements, and occupied areas.  For this reason, many homes provide the perfect conditions for mold to thrive, because they are constructed of organic dead matter, including many cellulose-based products.  These products include wood, particleboard, oriented strand board (OSB), engineered lumber, and paper-faced gypsum wallboard, as well as others.  Homes are also constructed of different, sometimes cheaper building material alternatives (i.e. OSB instead of plywood sheathing, plastic house wrap instead of tar paper).  In addition, homes are frequently poorly or incorrectly constructed (i.e. lacking proper roof/window flashings, penetration caulks/sealants).

 04 Mold Growth on Walls.jpg

05 Mold Growth in Kitchen.jpg 

Without moisture (i.e. water infiltration, plumbing leaks, elevated relative humidity, condensation accumulation), however, mold cannot grow.  Moisture is the key to combating mold issues in the home.  If you control the moisture, you can avoid mold issues and resulting building material and structural damage.

 06 Mold Growth Triangle.jpg


Realtors and sellers know that the presence of mold can quickly end a real estate transaction.  Since legal requirements for disclosing mold problems are not mandatory, buyers must rely on the seller's disclosure for such information.  It is not common for the seller to share this information.  In fact, they sometimes complete aesthetic repairs immediately prior to listing the home for sale.  That way the home looks as if no problems exist to the unsuspecting homebuyer, who's focused on how the home looks, instead of how it functions.  That leaves the buyer "rolling the dice" on their home purchase, especially if they decide not to hire a reputable industrial hygiene firm to conduct a thorough moisture and mold evaluation.  That's a bad idea, which will cost you, sooner or later.


Mold remediation is not only the removal of mold growth, water-damaged building materials, and elevated airborne spore concentrations from within a home to make it safe for occupancy.  It is also the correction of the moisture source.  Correcting the moisture source can be very costly and is often overlooked by less experienced inspectors/firms.

 07 Moldy House.jpg

Mold cleanup, on the other hand, only involves the cleanup of mold growth, water-damaged building materials, and elevated airborne spore concentrations within a home.  It does not include correction of the moisture source, which, if left uncorrected will result in the return of mold growth.  Some examples of these issues include: bathroom & clothes dryer exhaust vents discharging into the attic, roof leaks, plumbing leaks within ceiling & wall cavities, condensation accumulation and resultant leaks associated with poorly insulated pipes & windows, and moisture infiltration within a basement or crawlspace.


You cannot simply spray visible mold growth with an anti-microbial solution to kill it, or spray an anti-microbial encapsulant to cover it, like some contractors do, without physically removing the mold growth first.  Dead mold spores elicit the same allergic response as live mold spores do in sensitive individuals, so it is important that they are properly removed.

Mold cleanup is typically accomplished by first, constructing a containment around the affected area to prevent mold spores from contaminating unaffected areas during cleanup.  Next, engineering controls are installed, such as HEPA air filtration units that will clean the air and place the affected area under negative pressure if exhausted outside, with respect to unaffected areas.  This helps prevent spores from escaping the work area.  Before treating the surfaces, the affected building materials must be dried with low grain refrigerant (LGR) or other industrial-grade dehumidification units.

 08 Mold Remediation Worker.jpg

Now, the cleanup can commence, beginning by HEPA-vacuuming the visible mold growth and debris.  Next, damp-wiping, scrubbing, and in some circumstances, spray-applying the affected surfaces with an anti-microbial solution is conducted.  Following cleaning and sanitizing, surfaces must be allowed sufficient drying time.  Porous materials such as ceiling tiles, gypsum wallboard, fibrous glass insulation, carpeting, and carpet padding cannot be effectively dried and/or cleaned of visible mold growth.  It is typically recommended that these materials be removed under controlled conditions and discarded.  Depending on the severity, the entire cleanup process may need to be repeated.  Next, a visual inspection and moisture/mold evaluation is conducted, which includes sampling.  This is to ensure that the building materials have been thoroughly dried and that all visible mold growth has been removed.  Finally, the anti-microbial encapsulant is applied to lock down residual spores and fragments invisible to the naked eye on remaining building materials (i.e. wood framing).  Keep in mind, if a moisture issue remains or returns, so too will the mold growth.  There is no such thing as a mold-free guarantee and most insurance company policies exclude mold claims.


Mold can sometimes be difficult to locate.  It can be hidden within wall cavities, behind built-ins and cabinetry, under subfloors, and within infrequently used or inaccessible areas of the home.  Home inspectors are trained to visually inspect building systems and the general well-being of the home, but may not necessarily be able to identify a mold issue.  They do not typically utilize testing equipment that would allow them to identify moisture issues, such as infrared cameras, relative moisture meters, and relative humidity instruments, which are necessary for this type of evaluation.

A home inspector is typically not qualified to verify the existence of mold issues through visual inspection and sampling.  They may not indicate their lack of mold evaluation qualifications (i.e. industrial hygienist) in their report.  They will not likely be able to interpret the laboratory sample results, nor make recommendations for corrective actions.  Also, they are typically not licensed asbestos inspectors and lead inspectors/risk assessors, so you must hire an industrial hygiene consulting firm that employs these individuals.  Home inspectors referred by realtors may present a conflict of interest with regard to the home sale.  They may be pressured to give the home a clear report in order to continue receiving referrals.

Do-It-Yourself (DIY) mold test kits sold by big box stores are of limited use and typically receive mediocre ratings online.  They usually consist of a passive settle plate (i.e. Petri dish with a mold food source) and/or a surface swab.  The idea is for mold spores to settle out of the air or be collected with the swab and deposited onto the Petri dish.  If mold spores are present, and they almost always will be, they'll be collected on the sample and will grow into visible mold colonies within 24-96 hours.  They are usually checked for visible mold growth at 48, 72, and 96 hours, respectively, something you will not be able to do during the home purchase process.  Also, this will only test for live mold spores, not dead spores.  Both live and dead airborne and surface mold spore concentrations are used to evaluate whether a mold issue exists, especially the effectiveness of contractor mold remediation or cleanup efforts.  Testing for mold after the home purchase is too late, since now you've already inherited any existing problems.

 09 Mold Growth on Petri Dishes.jpg

Now you've confirmed that you have mold spores in your home, just like everyone else.  If you'd like to know what type of mold is present in your DIY sample, you'll need to send it to an accredited laboratory for analysis and wait 3-5 weeks for sample results.  The DIY sample kits that require an incubation period for mold to grow only test for living mold spores.  If a local industrial hygiene firm with it's own in-house laboratory conducts the evaluation, you'll have verbal laboratory results in 1-3 days.  You'll also have a written report detailing the evaluation, sample results, and recommendations for corrective actions in about a week.

Another problem with DIY sampling is that insufficient sampling locations are typically selected; only one affected area (i.e. basement), zero unaffected areas, and zero background samples (i.e. outdoors) are collected for comparison to the indoor samples.  This prevents the sample from being effectively evaluated, because it cannot be compared to any other samples or areas, especially if it's not analyzed at an accredited laboratory to determine the types and quantities of mold.  This is not good industrial hygiene practice.  Ideally, a minimum of three or more air samples and one or more surface samples must be collected to be cost effective for a residential client.  Many more samples must be collected to be statistically and scientifically defensible.

Hiring a reputable industrial hygiene consulting firm to conduct your moisture and mold evaluation, stucco evaluation, asbestos inspection, and/or lead inspection/risk assessment can potentially save you thousands of dollars.  It can also safeguard you and your family's health, provide peace of mind, and eliminate the headaches and heartache you would experience later, should you decide not to have your home inspected or evaluated prior to the sale.

The cost of a professional moisture and mold evaluation is negligible.  Especially when compared to the future out-of-pocket costs and negative impact that unidentified moisture issues, structural damage, resultant mold growth, and airborne mold exposure hazards can have on your family.

If you have questions, or would like to schedule an evaluation of your home or future home, please contact Eagle Industrial Hygiene Associates, Inc., at 215-672-6088.