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This article provides suggestions for where else to look for mold in buildings - places that are often forgotten but places that can harbor significant toxic or allergenic mold reservoirs. The fact that mold is said by some inspectors to be "hidden" in buildings does not mean one cannot find it by careful inspection and testing. Also see MOLD GROWTH on SURFACES for an index of what mold genera/species are frequently found on various building surfaces and materials.

We look for mold in buildings where it is not obvious by using context: where do we see leak stains, or where do we see building practices most likely to have produced a hidden leak or moisture problem? Ice dam leaks in walls, hidden plumbing leaks, roof spillage by the foundation, are all common clues that often track to a wet building wall or ceiling cavity and from there to a hidden mold problem which may need to be addressed.

This procedure helps identify the presence of or locate the probable sources of mold reservoirs in buildings, and helps decide which of these need more invasive, exhaustive inspection and testing. © Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Other Places to Look for Hidden Mold Contamination or Mold Growth

There are many places to look for mold growth. Here are a few others that you might not have considered:

• Underside of carpets or carpet padding that have been wet - check for moldy or water-stained carpet tack strips;
• Previously wet cardboard boxes and their contents;
• Ceiling penetrations like 120-V smoke detectors;
• Top of poorly-insulated exterior walls; behind wallpaper below windows which had a one-time or recurrent leak.
• Furniture: we often find extensive mold on the un-finished side of drawers, tables, game tables, and chairs that have been in a wet or damp environment.
• Imported Mold: Sometimes mold is imported into a "dry" building on furnishings or contents that were previously stored in a wet location or in another moldy building.
• Building Insulation is often moldy even if it looks clean.
• Appliances: Don't forget to clean your refrigerator, including gaskets, coils, and evaporator tray.
• Air Conditioning Systems: take a careful look at your window or wall-mounted air conditioner and be sure to make a complete inspection of central air conditioning system ductwork, registers, and air handlers, as well as any heating air handlers and duct work. Check especially downstream of the air handler on cooling systems since condensation there may promote mold growth.
• Have You Found Other Places to look for mold? Send us your own discoveries - your tips may help other people who are bothered by indoor mold but who have not been able to find its source.

Here are photos of more places to look for hidden mold in buildings

Here we provide a photo tour of mold which was hidden at least from some investigators and occupants, with photo and text tips on spotting problem mold in air conditioning systems, behind and under bath and other cabinets, mold under and in wall to wall carpeting, mold on stored paper files, file folders, and books, mold on, in, and under furniture, and mold behind wallpaper.

Where to look for hidden mold in air conditioning equipment interiors and in HVAC duct work

How We Find Hidden mold behind bathroom and other cabinets

Photos of mold behind a bathroom vanity cabinet base - shower water leaked across the bath floor, under the vanity, and into the wall cavity.

This was a small mold cleanup area, less than 10 sq .ft. and suitable for handling by a homeowner or handyman. The second photo shows the extent of mold after the cabinet was removed.

When we rebuilt this bathroom, since the tile floor slopes slightly down from tub towards the vanity base, as precautions against future mold growth we sealed all of the new vanity underside surfaces to reduce moisture and thus mold growth, and we caulked the vanity carefully at the floor level to prevent water from passing below.

Tips for Finding Hidden Mold Below Built-in Bureau Drawers

How to Find Hidden mold below wall to wall carpeting:

Hidden mold in and under wall to wall carpeting is notorious and widespread in areas which have been subject to wet conditions such as basements or floors on leaky slabs. The first photo at left shows moldy carpet tack strips which confirms a history of water entry and makes the carpeting highly suspect of serving as a problem mold reservoir. (We tested the carpeting further using a special vacuum mold test method.) The second photo shows clean carpet tack strips, indicating that at least since this wall to wall carpeting has been installed there has been no water below the carpet in this area, and suggesting that the risk of mold in this carpeting is low.

How to Spot Hidden mold on stored papers and files in cabinets:

Paper files and documents and file folders, even stored in metal file cabinets, can become quite moldy when left in a damp basement. In these photos the file cabinet was never itself wet, but the floor beneath it had been wet several times leading to extensive mold growth on these law office files. There are procedures for cleaning and salvaging moldy books and paper files, but the cost is high, making it appropriate only in special circumstances such as the preservation of works of art or valuable books or historic papers.

How to Recognize Hidden Mold on and in Furniture:

Upholstered furniture can be quite moldy if it has been exposed to flooding (photos above). Only in unusually severe circumstances will upholstered furniture be visibly moldy. Don't forget to look on the underside of couches, tables, and chairs, especially since the un-finished but hidden surfaces such as raw wood under a table or cabinet more easily take up moisture and support mold growth. The condition of the moldy green chair in the photo (left), from a lakefront cottage in Elk Lake Michigan, was pretty obvious after it had spent a decade in the damp cottage. Moldy furniture like this must either be discarded or stripped to its bare frame for cleaning before reupholstering. Remember to use your light (as we describe here and in other articles) to look along finished wood surfaces as often light colored problem mold is hard to see but may be quite extensive.

How to Find Mold Hidden Behind Wallpaper

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

HIDDEN MOLD, HOW TO FIND
  Photo Guide to Finding Hidden Mold
  Hidden Cosmetic Molds
  Hidden Mold Behind Paneling
  Hidden Mold Between Framing & Sheathing
  Hidden Mold in Flooring & Subflooring
  Hidden Mold in Wall Cavities
  Spotting Hard-to-See Mold
  Wall test cuts to spot hidden mold
  Light colored toxic molds
  Moisture Gradients and Mold
  Other Places to Look for Hidden Mold

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• Mold in Fiberglass Insulation© 2005 comments about a field study in process, & more about health hazards from fiberglass insulation - DJF
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• Contact Us to arrange mold/IAQ building on site inspection and testing.

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