Attic & Roof Mold ContamiHow to Find & Test for & Remove Mold in Attics
ATTIC MOLD - CONTENTS: causes, cures for attic mold contamination. How to prevent mold growth in building attics. Attic mold cleanup procedures. Use of encapsulants on mold in attics; correcting attic ventilation & mosture problems. Investigate attics for hidden mold in insulation or on ceiling materials under insulation.
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Attic & roof mold contamination causes & cures:
all attic mold is toxic or harmful. It is also not the case that
all attic mold needs to be cleaned or removed. It is not the case that all attic mold is going to
enter the living area or otherwise be a problem for building occupants. On the other hand some attic mold contamination can enter air handling equipment, ductwork, or occupied space and can be a risk to occupants. How do we determine the difference beween actionable attic mold and cosmetic mold? What must be done to clean up or remove attic mold contamination, and how do we prevent attic mold growth?
This article series on attic and roof mold contamination gives detailed step by step procedures and advice on how to find, test for, remove & prevent future mold contamination in building attics and roof cavities.
IS ATTIC MOLD A PROBLEM ? - Is attic mold a health risk or indoor air quality problem?
Toxic attic mold: The photo at the left was identified as a toxic mold that probably should be removed, although the ease of movement
of mold spores from an attic down into a living area varies widely from building to building.
Uncertain attic mold: The photo at the very top of this page shows where you may find mold growing on the attic side of ceiling drywall, particularly below
roof leaks or in areas of ice dam leaks at a building eaves.
We pulled back the fiberglass insulation to expose this
small area of mold growth. What about the white mold-suspect material observed on the rafters? Is that mold? If so is
it a problem?
The answer is, "it depends." In addition to testing to see what this material is (presuming there is a
large area of it), we'd also evaluate the chances of particle movement between the attic and the living space before
deciding on an appropriate approach to this moldy attic.
This article discusses attic mold in the following order:
How to evaluate the risk of toxic (or harmless) attic mold
Where to look for mold in a building attic
When is it necessary to tear off a roof to deal with attic mold?
When to use or not use media blast and use encapsulants for attic mold
Should attic mold even be removed? Are there other more important mold reservoirs to clean up first?
Which insulation is most or least likely to harbor non-visible mold
How can moldy air move downwards from an attic into occupied building space?
It is simply not the case that
all attic mold is toxic. It is not the case that all attic mold is harmful.It is not the case that
all attic mold needs to be cleaned or removed. It is not the case that all attic mold is going to
enter the living area or otherwise be a problem for building occupants.
It is however the case that attic mold indicates damp conditions
or leaks and therefore some further investigation or thought are in order.
Be sure to use the links at the left of this page to review other examples of mold found in attics on tongue-and-groove roof sheathing, brown mold and very dark brown, black-looking mold on attic plywood, and the risk of hidden mold in attic insulation.
RISK OF TOXIC ATTIC MOLD - How to Evaluate the Risk of Toxic Attic Mold
Here are some comments about air and particle movement in buildings and thus the chances that attic mold
will be transported from that area into the living space.
Air and particle movement in buildings tends to be up and out from lower floors to upper floors to attic.
There is not such easy particle movement downwards from an attic into a building.
Attic mold is less likely to be the significant mold problem source in a building than moldy lower areas such as basements, crawl spaces,
or wet building cavities.
Important exceptions to this normally-upwards movement of indoor air currents do occur however:
Attic or whole house fans: When a whole house vent fan is used and the attic venting is inadequate - resulting in a pressurized attic. When the fan is
operated, attic particulates, including mold, insect allergens, rodent fecal debris, mite fecals, bird droppings, dust, particles
(Histoplasmosis risk), may be blown downwards into the living area or into attic-mounted HVAC equipment.
Moldy attic knee wall areas: A moldy attic kneewall space adjacent to a bedroom on the upper floor of a cape cod
or similar house.
Pine roof sheathing: Older homes using pine boards as roof sheathing use a material which more readily supports growth of Aspergillus sp. and Trichoderma viride as well as other more problematic than I find in plywood-sheathed roofs.
Is Mold Sealed-Up in Building Cavities Hazardous?
When attic (or other building) surfaces or insulation contain a large reservoir of toxic or allergenic mold, AND if the area were inaccessible, say because the
space is too small to enter, then it may be necessary to remove some portion of roofing to give access for remediation, particularly if there is evidence
of transmission of problem mold from that space into the living area.
While some experts (Burge et als.) have opined that there is no important toxic mold spore movement from these "almost sealed" building cavities into occupied space, and thus that mold in building cavities is not a problem, our direct field inspection and test results, as well as client interviews and live field tests performed with clients have demonstrated that that assumption is not reliable, and that in at least some buildings, certain easily airborne mold genera/species such as Aspergillus sp. may move throughout the structure and may be a health concern for some building occupants.
The movement of mold-spore laden air in and out of building cavities and between building areas is not reliably predicable from a visual inspection, nor from simple air tests.
Simply turning a building fan on or off, opening or closing a window, turning up the thermostat, and many other conditions can change how air is moving in buildings.
Air Does Not Always Move Up and Out of a Structure as Building Science Would Suggest
Finally, building air sometimes moves contrary to what building science would lead us to expect. For example we assume that warm air rises up through buildings, passing out through roof ventilation. But direct measurement in some buildings has shown that warm air (including from a moldy attic) can sometimes flow downwards into the occupied space. Two examples that we have frequently observed in the field:
Air conditioning the upper floors of a hot building can cause a sufficient volume of chilled air to flow downwards (by gravity, through stairwells) at a rate that draws warm air down into the occupied space from an attic.
Use of a ceiling-mounted whole house fan to attempt to exhaust hot building air, combined with inadequate exit ventilation out through the attic or roof space can pressurize the building attic, blowing attic air (possibly warm or moldy) downwards into some building areas, air passing through openings cut for ceiling light fixtures, wiring, plumbing, or duct work.
This article is part of our series: MOLD in BUILDINGS which describes how to find mold and test for mold in buildings.
Readers of this article series about black, white, green and other colored mold on attic and under-roof surfaces should also be sure to read INSULATION MOLD CONTAMINATION TEST where we describe the risk of non-visible problematic mold hidden in building insulation.
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Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
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Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
"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
US EPA - Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
Associations: Sick House, Sick Building, SBS - Air Quality, Government, Private Associations and Information Resources
Atlas of Clinical Fungi, 2nd Ed., GS deHoog, J Guarro, J Gene, & MJ Figueras, Centraalbureau voor Schimmelcultures, Universitat Rovira I Virgili, 2000, ISBN 90-70351-43-9 (you can buy this book at Amazon) - The Atlas of Clinical Fungi is also available on CD ROM
"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 in Home Vegetable Gardens,"
Department of Plant Microbiology and Pathology,
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.
Ozone Warnings - Use of Ozone as a "mold" remedy is ineffective and may be dangerous.
Rot concerns in buildings-some building mold such as Meruliporia incrassata "Poria" risks serious rot and hidden structural damage
US EPA: Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
OTHER IAQ ISSUES: How To Find and Address Other Indoor Air or Indoor Environment Contaminants Besides Mold
Mold or allergens may not be the only or even the main indoor environmental contaminant. Don't let media attention to mold
cause so much enviro-scare fear that other, possibly more urgent hazards go un-addressed.
Rodents, Mice, Squirrel Control - I find high levels of mouse and rodent dander, fecal dust, and urine-contaminated dust in some buildings,
and high levels of these materials in building insulation in those locations. If you have a mouse problem, particularly if mice and their waste (fecals or urine) are contaminating
the building HVAC or building insulation, may need both steps to clean up or remove infected materials and steps to stop an ongoing
rodent problem. If squirrels are a problem, the cleanup needs to include closing off entry openings into the building. Get some
help from a licensed pest control expert.
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: firstname.lastname@example.org. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones