Photograph: Mold under carpeting on tack strips indicate history of water entry, suspect moldy carpet - Daniel Friedman A Home Buyer's Guide to Mold Inspection & Testing

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Mold inspecting or testing advice for home buyers:

This article gives advice to home buyers concerned about inspecting and testing for mold in a building to be purchased but where there is not already a known mold problem.This website describes when and how to find mold and test for mold in buildings and how to correct mold problems.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Mold Inspection and Testing Advice for Home Buyers

Because it is perfectly normal to find some mold spores in air everywhere and because mold is ubiquitous in the environment, it makes no sense to attempt to buy a "mold free" home, nor should your objective be to test a prospective new home to be sure that there is no mold therein.

You can't eliminate mold in the environment indoors nor outside. If you could we'd all be in trouble as nothing would ever decay and we'd all be so buried in junk and debris that nothing could grow on the earth.

But we don't much like to see growing mold contamination on surfaces or materials indoors and certainly not on our walls, ceilings, or furniture. There we remove it or clean it off. Because there are potential health risks involved, especially for some people, and because there are significant costs involved in large mold remediation projects, home buyers often contact us to ask about testing a home for mold during the home buying process.

A thorough building investigation for problematic mold needs to address hidden mold reservoirs, for which our approach is to complete a detailed inspection and building (leak) history as well as to record occupant observations and complaints.

A low-cost superficial test or superficial "quick look" for problem mold (such as an "air test for mold", a "home test kit for mold" or a "mold culture test") is likely be a waste of money since those approaches to screening a building for mold contamination are unreliable. Certainly if problem mold is visible that's unambiguous. But superficial visual inspections and grab-tests for mold in air or on surfaces, performed without being accompanied by a very thorough building inspection, history taking, and occupant interview, have a high risk of missing important reservoirs of problem mold in a building.

Some "mold inspectors" may charge as much as a true expert to examine your building ($750 to $2000) but in fact may be doing little more than a quick inspection for visible mold and a few superficial tests. This is also an unreliable approach.

Since water and moisture are gating factors for indoor mold contamination I recommend that you start with a thorough inspection of the building for conditions likely to produce a mold problem - leaks, moisture traps, bad ventilation, history of flooding, etc.

Why Can't I Just Collect a Mold Sample and Based on That, Decide if the House We're Buying Has a Mold Problem or Not?

Reader Question: Quick Lab Turnaround on Mold Tests

Dear Lab Director:

We desperately need the results of the mold sample we collected yesterday ASAP. We cannot proceed with the closing process until we have these results, and our house purchase closing is scheduled for Friday. - Worried in Po-Town.

Reply: Don't Decide to Buy or Not Buy a Home Based on a "Mold Test"

Dear Worried:

While most mold test labs and forensic laboratories can provide very fast mold sample analysis - 24-hours or less after a sample is received, a home buyer who is worried about a possible costly mold contamination problem in a building should certainly not be deciding to go ahead with the sale or not simply based on a "mold test".

This is even more true if the mold test or mold sample was collected by someone who is not an expert.

If there is a reason to be worried that there is a significant mold problem in a building, and if you have not had an expert perform a very thorough, visual inspection, even the most technically proficient "test", alone, is unreliable.

A mold test, even a good one, is a screen that might detect evidence of an indoor mold problem.

But absence of evidence of mold in a building is not, unless accompanied by an appropriate, expert, onsite investigation, never evidence of absence of a mold problem.

If you have a particular concern about the building, and regardless of the outcome of the lab work, we recommend that you discuss this with your attorney, your realtor, and your home inspector. Your attorney may recommend that you either delay the closing, or if agreeable to the seller, obtain some estimates to establish a "worst case" guess of possible mold remediation cost and escrow that amount long enough to give yourselves time for an expert assessment.

Does this mean every home should be inspected and tested by an expert to look for mold?

Of course not. At MOLD / ENVIRONMENTAL EXPERT, HIRE ? we discuss some criteria that help decide if it is appropriate to bring in a mold expert, such as pre-existing evidence of a problem: large areas of visible mold, evidence of or an historical report of building flooding, significant plumbing leaks, or other leaks, etc.

Reader Question: How do I make sure a previously-contaminated home I'm buying is not contaminated with black mold


I am looking into purchasing a home and found some histroy on the home that led me to do a mold testing. The house used ot have black mold in the basement and in the second floor bedrooms (rooms D/T windows being knocked out when abandoned). The house has been "gutted" and remodeled, however, having a 2 year old son- I want to make sure I understand things okay. - CB April 18 2015

My husband and I are looking at purchasing a house that we have an accepted offer on. We came about some pictures that showed the hosue before it was "gutted" and came to realize there was extensive amounts of black mold in the basement (then unfinished) and second bedroom floors (windows were knocked out when abandoned). The house has been completely remodeled. We did a mold analysis which I have the results of. On the second floor, tehre was 1 raw count or 40 spores per cubic meter of Chaetomium- what is this and is this of concern? Also in the basement, there was 1 raw count or 40 spores per cubic meter of stachybotrys. Is this of concern as well or with the histroy is this okay and small/safe? Thank you for any guidance you can give me! We are going at this blindly! - CB April 18 2015


I'm sorry to give bad news, but "spore counts" as a building screen for mold are very unreliable, and looking for "black mold" is also dangerous since of the 200+ common mold genera/species that can grow indoors in buildings or on building contents, many of which are harmful, the "black" group is but a small subset.

Worse, if you used a culture test, since 90% of molds don't grow on culture, your test was basically 90% wrong when you opened the box.

If you're worried about mold start with a thorough building inspection to understand its leak history: what got wet, where did water go, what cleanup was done, vs. what was "covered over". If there are reports or photographs of the prior mold contamination those will be a helpful source of information on what work was done. If the mold contamination was serious - more than 30 square feet of contiguous and non-cosmetic mold - then a professional should have been used to perform the cleanup. In that case there should have been independent mold inspection reports from before and after the cleanup job both indicating what cleanup was needed and indicating that the cleanup was properly conducted.

At MOLD CLEARANCE INSPECTIONS we describe how that final inspection should be performed.

A competent onsite inspection by an expert usually finds additional clues that would permit a more accurate, complete, and authoritative answer than we can give by email alone. You will find additional depth and detail in articles at our website.

If you have reason to think that the cleanup was inept, or that contaminated drywall, insulation, or other materials were not removed, then select the highest-risk points and if necessary make a small test opening to inspect cavities such as a ceiling or wall.

Reader Question: mold under my house came in as 120 and upstairs at 1200 - is that bad?

Hi 'i recently had a mold inspection " the number for under the house cane as 120" but in our room it came back as 1200 an thats from air samples " is this bad ? What should we do ?an its a single family home an we do not have ceiling fans " please help me understand. - S.L. 14 April 2015


I'm sorry but no one can make much sense out of arbitrary numbers: we have no idea what they represent. Since you had a mold inspection, surely the inspector actually inspected the home. What did he or she say about the mold report when you asked?

Reader follow-up:

he said that it was very bad in the home i should seek medical advise an contact an attorney


If that is all you were told I'd start by asking for a full refund of what you paid.

Send me all information you have and I will perhaps be able to say something useful.

But just the data you've given me is not enough to make sense of the advice you report having been given.

Why to Hire a Good Home Inspector for a Preliminary Check for Mold-Producing Conditions in a Building

If your "mold inspector" is simply going to enter the building, collect a few air, surface, or culture samples, and perhaps report on obvious visible mold in the living space, you're not receiving a very professional nor very reliable service.

An experienced, thorough, detailed, qualified home inspector will be much better at recognizing those (mold-conducive) conditions than a typical "mold inspector" or a typical industrial hygienist who does not know building science and who lacks experience in identifying where and why mold problems occur in buildings.

Home inspection standards, training, and experience teach inspectors where water, leaks, and moisture problems occur in buildings. Here are some examples of water or leak history problems that can create a hidden mold problem in a building:

A home inspector is expected to recognize these leak and moisture problems even though s/he is not performing an environmental inspection.

Also see MOLD TESTING by HOME INSPECTORS? for an opinion-text on the marketing of mold tests as a revenue source for home inspectors.

A Home Inspection is not an Environmental Survey of a Building

Unless the inspector happens also to be trained in mycology, forensic microscopy, and aerobiology, s/he will be focused on the condition of the building, not just on the presence of mold, but such a person is the best expert to identify leaks and moisture problems among other building risks.

Don't try to force the inspector to give an environmental report - it's outside the scope of a home inspection.

But do ask the inspector to be extra thorough and detailed about leaks, moisture, ventilation defects. And of course any conscientious and respectable inspector will also tell you if s/he happens to also actually see mold (or other out-of-scope hazards) during the inspection.

Key Mold Contamination Articles for Home Buyers


Continue reading at WHAT MOLD LOOKS LIKE or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Suggested citation for this web page

HOME BUYERS' GUIDE to MOLD INSPECTIONS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia


Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

HTML Comment Box is loading comments...

Technical Reviewers & References

Click to Show or Hide Citations & References

Publisher's Google+ Page by Daniel Friedman