Mold under wallpaper (C) Daniel Friedman Big Mold Testing, Inspecting, & Cleanup Mistakes to Avoid

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Here we list big and costly mistakes that people make when cleaning up moldy buildings. We start with unnecessary mold testing and unnecessary professional mold remediation for small mold contamination areas. This article in our "How to Clean Mold" article series describes common mistakes people make when attempting to clean up mold.

Avoiding these mold cleanup errors can save you money and may also avoid dangerous side effects of bleach, mold chemicals, or ozone when improperly applied. Our page top photo shows mold growth behind wallpaper under a leaky window in a condominium in New Jersey. Just wiping off the wallpaper surface was not very helpful.

But the entire scope of this mold contamination was trivial - just about two square feet. Was mold testing needed? Mark Cramer assisted in development of this material.

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4. MOLD CLEANING MISTAKES people make when cleaning-up moldy building materials and moldy surfaces

Small area of moldy drywall (C) Daniel Friedman

[Click to enlarge any image]

This discussion lists common mold remediation or mold cleanup errors specific to attempts to clean mold from contaminated framing lumber or building sheathing such as plywood or pine boards used for subfloors or roofs.

Article Series Contents

Inadequate cleaning and cross contamination are the two most common mistakes we find when inspecting and testing sites to perform a post remediation clearance for mold cleanup.

Using bleaches, sprays, or ozone instead of cleaning are close behind in frequency of mistakes.

Other mold remediation errors such as performing only demolition and failing to clean up the dust and debris caused by that step, are important but are not discussed in this moldy wood cleaning document.

UNNECESSARY MOLD CLEANUP EXPENSE - using extreme, costly measures when inappropriate

Throwing money at mold: At MOLD / ENVIRONMENTAL EXPERT, HIRE ? we list the questions to ask when deciding just how far to go in inspecting and testing for problem mold in a building.

Small areas of mold: In short, if a mold problem is trivial, less than 30 square feet of contiguous mold, and if none of the risk factors that would suggest a thorough investigation apply, then mold cleanup can be handled as a normal building cleanup and renovation project.

Our photo (left) shows a small area of mold on drywall in an otherwise problem-free no-complaint home. Notice that dark line at right angles to the wall at lower left?

Furniture or boxes were stored in this corner, reducing air circulation and increasing condensation on the cooler wall corner - possibly the cause of mold growth on this surface. If there were no known or suspected leaks into the wall we probably have a small do-it-yourself or handyman mold cleanup project. The cost of professional testing and remediation are not justified.

For small area mold cleanup see DO IT YOURSELF MOLD CLEANUP and if you're not sure where to start,


This article offers advice on cleaning mold found on surfaces of both finished & un-finished wooden building materials such as framing lumber (rafters, floor joists, wall studs), and building roof, wall, and floor sheathing such as plywood, tongue-and groove pine boards, and other structural wood surfaces in buildings.

We discuss the pros and cons of using fungicidal sealants and bleach on wood surfaces and give sources and list types of those products. We also discuss common errors made when cleaning wood surfaces, such as relying on bleach or performing expensive and unnecessary cleaning on cosmetic black mold on wood surfaces.

SMALL MOLD CLEANUP WARNING: even during a minor mold cleanup job, keep alert for the discovery that there was actually a large but previously unknown mold problem.

So if you are removing two square feet of moldy drywall and you find that the wall cavity side of the drywall is moldy you'll need to keep removing drywall until you've found a 24" or one stud (or joist) bay of clean drywall surface. If the size of that cleanup project grows to exceed 30 square feet of contiguous mold, stop the job and bring in an expert to give advice. Otherwise you risk spreading moldy dust and contaminating other building areas.

Photograph: typical cosmetic bluestain mold on new framing lumber, floor joists - © Daniel Friedman

Cosmetic Mold or Non-Mold Stuff that is harmless: Also be sure you're not spending unnecessarily to clean up stuff that's not even mold (mineral efflorescence) or to clean up harmless cosmetic mold (which you may be able to determine by simple visual inspection).

See Stuff that is Not Mold for photos of things that are sometimes mistaken for mold.

See Molds that are Harmless - Cosmetic for photos and description of Blue Mold and Ceratocystis/Ophistoma - cosmetic black molds found on framing lumber.

COSMETIC MOLD WARNING: When we sampled at a chain of lumber supply stores and at some building sites we found that on treated lumber that has been prepared green and wet we sometimes find a mix of both harmless cosmetic mold and possibly harmful Aspergillus sp. or Penicillium sp. - so if these products are to be used indoors they might need to be surface-cleaned.

Mold Cleanup Articles


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