Table of Kinds of Mold Growth Found on Building Surfaces InspectAPedia® -
Detailed table lists mold genera/species most often found on specific building surfaces, materials, or contents
Which molds are most commonly found indoors?
What are the Most Common Indoor Molds Found on Building Surfaces?
Most common molds on drywall, paper, wood, plastic, metal, furniture, bedding, clothing, shoes, etc. in or on buildings
Here we provide a table of molds most commonly found on specific building surfaces or in/on building materials, furnishings, and other building contents.
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Our page top photo of a mold damaged home shows an area with many different surfaces, materials, and in some cases different genera/species of mold contamination.
Like bird-watching, knowing what molds are likely to be present, what they look like,
and what they like to eat, in other words, knowing some mycology, can make a significant difference in what a building inspection for
mold actually turns up.
The difference between what molds are found in buildings and what molds commonly grow on various building surfaces is that most mold tests and mold reports involve samples collected by people who are not expert at recognizing and sampling mold in buildings. So easy-to-see molds are over-reported and hard-to-see molds are under-reported in consumer-generated mold tests and samples. This reporting error also confounds attempts to correlate mold related illness and sick building complaints with specific genera or species of indoor mold.
Simple "mold screening methods" which omit the inspection, and "test only" sampling methods, such as air and culture methods
can produce very unreliable results when used quantitatively - as we discuss at
IAQ Methods and at other articles at this website.
Table of Common Indoor Molds Found on Building Surfaces
We list here the most common mold genera/species that our field investigations have detected in the screening of more than 2000 buildings between 1986 and the present.
We are conducting ongoing research on the presence of specific molds on building surfaces and materials. Comments, critique, and contributions are invited. Contact Us.
Wet or Moldy Furnishings: following a building flood or water entry, some items that have been soaked do not need to be tested for mold contamination. A mattress that has been soaked (photo at left), had visible mold growth, or smells moldy is best just discarded. In our mold table below we include additional comments about furnishings that have may not have been wet but that may be mold-contaminated.
NOTICE: the molds we list as most-commonly found on building surfaces and materials in the table below are by no means the only genera/species that may appear in a specific build ling or case. Further, the mold genera/species that grows on a particular surface depends primarily on its growth conditions, in particular moisture level, and of course temperature, light exposure, and similar factors.
It is often the case that multiple mold genera/species are present on the same surface; some molds may be growing parasitically on others, and the particular mold found at a particular spot on a building surface may depend on the moisture level at that location.
Our investigations include extreme-mold cases in which a building had been subjected to severe water damage and left unattended for weeks or months, leading to extensive mold growth throughout the structure on many or nearly all surfaces. In those extremely-moldy buildings we collected tape samples of mold on each different type of surface or material in the building as well as collecting vacuum and air samples of mold to observe the dominant airborne molds in those environments.
Our OPINION is that the genera of Aspergillus ranks as a wide-lead first as most widely adapted to grow on the greatest number of different indoor building surfaces, with Penicillium sp. probably second. As we discuss at MOLD FREQUENCY in buildings, these two mold genera are probably under-reported by consumers who collect mold samples using test kits as well as many mold test consultants who naturally focus on the most visually obvious dark or "black" molds in buildings. Outdoors we most often find the king of molds, Cladosporium sp. on widespread building surfaces.
Table of Common Indoor Building Molds on Surfaces or In Materials
Building Surface or Material Links Photographs of Mold on Various Materials found On or In buildings
Common in various duct systems especially where normal organic building dust and debris accumulate along with water downstream of condensate blow-off in the air handler or where condensation has occurred, or where external air duct leaks occurred into rooftop mounted ducts or where building ducts were exposed to flooding.
Refrigerator gaskets: Cladosporium sp. / C. sphaerospermum
Presence of mold probably depends mostly on the presence of organic dust and debris such as food, grease, house dust or animal dander.
Very different molds grow on painted or porcelain appliance surfaces than those most often found on rubber or plastic parts.
Art works (joint project photo courtesy Ulrik Runeberg, Museo de Arte Contemporaneo de Puerto Rico), oil on canvas (others available)
Cladosporium sp.; also Penicillium sp. & Aspergillus sp. especially on masonite substrates
Varies widely by paint chemistry, substrate of fabric, hardboard, wood, and varies significantly between exposed surface and hidden surfaces. (Study projects with several art museum conservators include mold contamination, bleed-through from hardboard substrates, and paint failures on historic buildings and artifacts.
May vary by fabric fiber type, cotton vs. synthetic
Books, mold on books
Aspergillus sp. on cloth bindings
Cladosporium sp.; on exposed edges of paper, varying by organic dust level;
Varies significantly by binding type and glue, cloth, paper, etc.
Cabinets, kitchens or bath vanities, visible and hidden mold
Aspergillus sp.;
Penicillium sp.;
Varies by cabinet material, wood, pressboard, paint, and presence of kitchen grease or food particles; Also very significant variation between coated or finished surfaces and un-coated or un-finished surfaces such as cabinet backs.
See Green Mold for photos of green mold on indoor cabinets & furniture.
Doors, hollow core luan or vinyl-coated, painted and un-painted surfaces, visible and hidden mold
We find that different mold genera/species grow on different hollow core surfaces where wood species vary, for example different molds will be found on the luan door face than on the pine door edges.
Doors, solid wood, pine, painted or clear-coated and unpainted, visible and hidden mold
Drywall, gypsum board, visible and hidden mold - very common mold reservoir in buildings where drywall has been wet, exposed to flooding, or exposed to high humidity - don't forget to check wall cavities Drywall gypsum board (such as Sheetrock™), not treated for mold resistance, visible and hidden mold
Stachybotrys chartarum - most wet area.
Cladosporium sphaerospermum,
Aspergillus sp., A. flavus.
Penicillium sp.;
Synonym: gypsum board. Significantly, mold growth may be rare or absent on un-painted joint compound at tape joints. Mold growth on drywall generally varies by genera/species at different heights from a wet floor as moisture level in the material varies. Mold growth on drywall may be interrupted at horizontal drywall joints. Mold growth on the exposed "room side" of drywall may be a different genera/species and also very different in quantity from mold growth found on wall-cavity side.
See SAMPLING DRYWALL for an example of three different molds on drywall at different moisture levels and heights from a wet floor.
See Black Mold for photos of several different black molds on drywall.
See Red Mold for very moldy wall cavity side of drywall that showed no mold on the exposed or room side.
Also see SHEATHING, Gypsum board.
Many mold species, varying by moisture level in the drywall at different locations or distances from the moisture source (such as a wet floor in a basement or a laundry room)
Ducts, fiberglass-lined HVAC, visible and hidden mold
Cladosporium sp.; C. sphaerospermum;
Rare: Aspergillus sp.;
Penicillium sp.;
Stachybotrys sp. on paper facing;
Ducts, plastic lined HVAC, visible and hidden mold
Rare.
Depends on the presence of house dust (containing organic debris) and presence of moisture.
Doors, interior, hollow core, visible and hidden mold
Aspergillus sp.;
Penicillium sp.;
Varies by wood species and coating. Hollow core luan doors show different mold genera/species on the luan surface from that found on the surface of solid pine used in door edges. Variations also among coatings: paint, stain, varnish, polyurethane.
See White Mold for photos of moldy solid and hollow core doors.
Doors, interior, solid pine, visible and hidden mold
Aspergillus sp.;
Penicillium sp.;
Varies by coating.
Fiberglass, visible and hidden mold
see Insulation
Floor sheathing, OSB oriented strand board, visible and hidden mold
Cladosporium sp.; C. sphaerospermum;
Stemonitis sp.
See Brown Mold for photos of mold on OSB including stunning photos of Stemonitis sp. on a bathroom floor.
Floor sheathing or subflooring, plywood, visible and hidden mold
Aureobasidium pullulans common in attics on roof sheathing;
Cladosporium sp., C. sphaerospermum, common on roof sheathing;
Less common: Taeoniella sp., T. rudus, on plywood subfloor exposed to leaks such as at sliding entry doors.
See Black Mold for photos of Taeoniella sp., T. rudus, and other dark molds on plywood.
See Green Mold for photos of green mold on plywood subfloor over a wet crawl space.
Floor sheathing, pine tongue & groove, visible and hidden mold
Aspergillus sp.;
Penicillium sp.; Trichoderma sp., T. viride (green), and T. harzianum
Flooring, vinyl tiles or sheet vinyl, visible and hidden mold
Flooring, wood strip, visible and hidden mold
Framing lumber, wall studs, ceiling joists, roof rafters, un-treated lumber not painted, visible and hidden mold
Ceratocystis/Ophistoma black mold group - see Cosmetic Mold
Cladosporium sp. / C. sphaerospermum;
Less common:
Aureobasidium pullulans; (more common on plywood sheathing)
Aspergillus sp.;
Penicillium sp.;
Trichoderma sp.;
May vary by wood species;
Varies by treated vs. un-treated lumber;
Varies by coated or un-coated lumber;
We find parasitic mold growth on top of cosmetic mold growth on some lumber, both un-treated and treated.
Depends on wood species, wood coating; Check un-coated surfaces such as under bureau drawers and the under-side of chip board or particle board furniture such as game tables and pool tables. See Green Mold for photos of green mold on indoor cabinets & furniture.
In addition to surface mold, mold growth inside of upholstered furniture may be present and may be detected by vacuum methods. See Black Mold for photos of moldy upholstered furniture.
Glass surfaces indoors, visible and hidden mold
Cladosporium sp.;
Depends on deposition of organic debris;
Hardboard products such as Masonite, used for pegboard, paneling, or for works of art as a painting substrate
Homasote & other fiberboard insulating board and sheathing products, mold, visible and hidden
Aspergillus sp.;
Uncommon, found in flooded homes subject to extreme mold growth
HVAC equipment: air conditioner or heating system air handlers and blowers, especially where organic house dust and debris accumulate
Cladosporium sp.;
Insulation, asbestos pipe, visible and hidden mold
Stachybotrys sp.; Aspergillus sp.;
Mold growth depends on paint coating, fabric fibers (cotton wrap), and moisture exposure. See See Black Mold for photos of mold on asbestos pipe insulation.
Insulating boards, styrofoam, urethane foam, others, visible and hidden mold
Insulation, cellulose, visible and hidden mold
None of our field samples have detected mold contamination in this material.
We postulate that the fire retardant chemicals used on blown-in or loose-fill cellulose building insulation retard mold growth. The life expectancy of this mold resistance may be affected by time or by exposure to water. See Cellulose loose fill insulation
Penicillium/Aspergillus sp. inside of fiberglass insulation in floors, walls, attics, cathedral ceilings where leaks have occurred
Significant levels of mold contamination may be present but not visible to the naked eye, in insulation that has been wet or exposed to high moisture, or exposed to high levels of airborne mold from building demolition. Special insulation vacuum test methods are used.
Additional mold genera/species appear on foil or kraft-paper insulation facing.
Mold growth on closed-cell foam insulating board is invariably surface-only and appears to depend on the presence of organic dust or debris. May vary by type of foam and by foam board coatings such as foil or paper. See Foam Board Insulation
Insulation, sprayed icynene, visible and hidden mold
We have not detected mold growth on this material
Mold growth may be possible on icynene foam depending on its exposure to airborne organic dust and debris. See Mold in Foam Insulation
Mattresses, not covered by other materials, visible and hidden mold
May vary by mattress cover fabric type, cotton vs. synthetic mix; mold growth inside of mattresses may be present and may be detected by vacuum methods.
Mattresses or bed linens that smell moldy - MVOC contamination
It's unlikely a moldy mattress that was actually wet or suffered mold growth can be cleaned adequately, but unfortunately that experience also extends to a mattress that has had prolonged exposure to MVOCs and just "smells moldy" - usually a smelly mattress is also replaced as part of mold remediation
Metal surfaces, e.g. stainless steel kitchen sink, visible and hidden mold
Mold growth probably depends on the presence of food or other organic dust and debris
Mobile homes, visible and hidden mold in various locations associated with most common moisture and leak risks on these structures: wall cavities below windows, floors, subflooring, crawl area insulation, roof cavities
Modular homes, visible and hidden mold in cavities and locations peculiar to modular home construction methods and due to leaks during transport of modular home units in wet weather
Pergo type laminated flooring products, visible and hidden mold
Uncommon.
Flooring that has been flooded needs to be removed where water has passed below.
Pine boards, solid pine wood used for trim, paneling, flooring, or subflooring with variation with subflooring age and exposure to moisture, and between painted or coated-sealed sides and un-finished (usually wall cavity) side, visible and hidden mold
Aspergillus sp. / A. flavus, A. versicolor
Trichoderma sp.;
Cladosporium sp.;
Plaster walls, ceilings, raw plaster & painted plaster, visible and hidden mold
Roof sheathing, pine boards, T&G, visible and hidden mold
Aspergillus sp.;
Penicillium sp.; Trichoderma sp., T. viride (green), and T. harzianum
Found in poorly vented and leaky attics of older homes; found in some attic knee wall areas on roof and floor sheathing;
See White Mold for photos of moldy tongue and groove roof sheathing.
Roof sheathing, plywood, un-treated, visible and hidden mold. Also see OSB sheathing discussed above.
Varies by wood species, coating (paint, stain), and exposed vs. hidden surface.
Also see Also see ROT, FUNGUS, TERMITES.
Vinyl sheet flooring, visible and hidden mold; vinyl exterior siding
Cladosporium sp.;
Varies between upper surface and underside, flooring materials, paper, glue or adhesive, and presence of organic debris
Don't mistake algae on vinyl exterior siding for mold;
Stachybotrys chartarum, especially on hidden surface where leaks have occurred or in baths. See Black Mold for photos of S. chartarum behind wallpaper.
Varies by age, wallpaper colors, pigments, dyes, and adhesive; some antique green wallpaper pigments interact with some molds to release arsenic.
Varies by material, paper, vinyl, fabric
Varies by coating, foil, paint, vinyl, plastic.
Varies by surface, room-side vs. wall-side of wallpaper may be completely different, or present only on the hidden side of wallpaper.
Wall sheathing, fiberboard, Homasote™ (also used as insulating board inside of building foundations), visible and hidden mold
Homasote™ and similar soft fiberboard materials are made of paper or softwood fibers. We have found significant mold growth only when the material was subjected to very wet conditions for a protracted period in basements or wall cavities.
See Hidden Mold in Wall Cavities
Water heaters & other painted or porcelain coated steel jacketed appliances, metal surfaces
Cladosporium. sp./C. sphaerospermum;
Windows, interior side, visible and hidden mold
Cladosporium sphaerospermum often found on window muntins subjected to water from condensation; many molds are deterred from window growth by exposure to light and UV.
Varies by window material, wood, vinyl, metal, and by coating, paint, stain, un-finished.
Wood building sheathing, roof or exterior wall, visible and hidden mold.
1. We have been using special methods to test fiberglass building insulation for Penicillium/Aspergillus sp. in areas where
the insulation has been wet or where insulation has been exposed to active mold growth such as over a wet crawl space or a moldy basement.
3. Some of the molds listed in this table, even though found indoors, are unlikely to be indicative of a growing
mold reservoir of that genera/species. For example, we often find Cladosporium herbarium and certain Basidiomycetes
such as Ganoderma sp./G. applanatum/G. tsuge in indoor air samples but we have not found these genera/species
growing on building materials. Rather they enter in outdoor air.
In conclusion, this interesting table needs additional research with data provided by expert building investigators rather than
self-collected data by individuals who spot first and sample first dark molds on building surfaces. Readers should see
How to Look For Mold.
MOLD ATLAS & PARTICLES INDEX, Pathogens, Allergens and Other Indoor Particles - actual and possible medical health effects of Mold (separate online document)
MOLD GROWTH ON SURFACES, PHOTOS Photos of what mold looks like in buildings, organized by mold growth on various kinds of building surfaces and contents or items found in buildings. Mold in situ. MOLD GROWTH on SURFACES, TABLE OF, Summary table of what mold genera/species are frequently found on various building surfaces and materials
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Additional technical contributors & reference sources for this article are listed below.
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Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
Atlas of Indoor Mold, Online Clinical Mold Atlas, Toxins, Pathogens, Allergens and Other Indoor Particles - Medical Health Effects of Mold (separate online document)
Building Floods: quick steps after a building flood or plumbing leak can prevent costly mold contamination
Classes of Mold: what types of cosmetic, allergenic, or toxic mold are a problem? Can mold be cleaned-up successfully?
"A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
"Disease Prevention Program for Certain Vegetable Crops," David B. Langston, Jr., Extension Plant Pathologist - Vegetables, University of Georgia (PDF document) original source: www.reeis.usda.gov/web/crisprojectpages/209797.html
"Disease Prevention in Home Vegetable Gardens,"
Patricia Donald,
Department of Plant Microbiology and Pathology,
Lewis Jett
Department of Horticulture, University of Missouri Extension - extension.missouri.edu/publications/DisplayPub.aspx?P=G6202
Fifth Kingdom, Bryce Kendrick, ISBN13: 9781585100224, is available from the InspectAPedia online bookstore - we recommend the CD-ROM version of this book. This 3rd/edition is a compact but comprehensive encyclopedia of all things mycological. Every aspect of the fungi, from aflatoxin to zppspores, with an accessible blend of verve and wit. The 24 chapters are filled with up-to-date information of classification, yeast, lichens, spore dispersal, allergies, ecology, genetics, plant pathology, predatory fungi, biological control, mutualistic symbioses with animals and plants, fungi as food, food spoilage and mycotoxins.
Fungi, Identifying Filamentous, A Clinical Laboratory Handbook, Guy St-Germain, Richard Summerbell, Star Publishing, 1996, ISBN 0-89863-177-7 (English)
Mold Action Guide: Step-by-Step Instructions, What to do about mold, mildew, and other indoor allergens
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