ASTM D7338-14(2023)
(Guide)Standard Guide for Assessment Of Fungal Growth in Buildings
Standard Guide for Assessment Of Fungal Growth in Buildings
SIGNIFICANCE AND USE
5.1 This guide presents options for a systematic assessment of fungal growth in buildings.
5.2 This guide allows for site-specific flexibility and professional judgment in the choice of assessment procedures. It may not be necessary to perform in its entirety the basic assessment presented below to resolve a particular problem, for example, where fungal growth is localized and the source and extent of moisture is readily observable.
5.3 Conversely, no matter how comprehensive the survey, all fungal growth may not be identified or located in a fungal assessment.
5.4 Material removal or destructive investigation may be needed to access suspect surfaces.
5.5 Using the procedures described in this guide, the investigator may have obtained the data necessary to suggest specific recommendations, for example, how to remediate the observed fungal growth, or how to prevent further fungal growth, but those recommendations are beyond the scope of this guide.
5.6 Precautions may be needed to protect the assessor and building occupants where access may disturb fungal growth.
5.7 It is the user’s responsibility to protect information that may be considered confidential, or private, or both, in accordance with project contract, corporate protocol, or local, state, and federal regulations, or a combination thereof.
5.8 It may be necessary to enlist other disciplines or trade expertise to assist in some steps of the assessment, but recommendations of when to enlist and whom to enlist are beyond the scope of this guide.
SCOPE
1.1 This guide provides a compendium of information and a menu of options for assessment of fungal growth in buildings, but does not recommend a specific course of action. Due to the wide variety of fungal problems affecting buildings and their occupants, and the wide variety of buildings, it is not possible to describe a set of uniform steps that will always be performed during an assessment (that is, a standard practice); therefore the user of this guide must decide which steps are appropriate for a given situation or building.
1.2 This guide is specific to fungal growth, which is only one potential problem in a building environment. It may be part of, but is not intended to take the place of, a comprehensive indoor air quality investigation.
1.3 This guide describes minimum steps and procedures for collecting background information on a building in question, procedures for evaluating the potential for moisture infiltration or collection, procedures for inspection for suspect fungal growth, and procedures beyond the scope of a basic survey that may be useful for specific problems.
1.4 Assessments for fungal growth may be useful wherever fungal growth is suspected, excess moisture has been present or when there are concerns regarding potential fungal growth.
1.5 Periodic fungal assessment in buildings may be a component of preventative maintenance programs.
1.6 This guide is applicable to buildings including residential (for example, single or multi-family), institutional (for example, schools, hospitals), government, public assembly, commercial (for example, office, retail), and industrial facilities.
1.7 Recommendations for developing a sampling strategy or methods for the collection and analysis of fungal samples are beyond the scope of this guide. For recommendations for developing a sampling strategy, see Ref (1)2, Chapter 10.
1.8 Recommendations for remediation of fungal growth are beyond the scope of this guide.
1.9 This guide is not intended to supersede any government regulations governing the assessment of fungal growth in buildings.
1.10 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use...
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7338 − 14 (Reapproved 2023)
Standard Guide for
Assessment Of Fungal Growth in Buildings
This standard is issued under the fixed designation D7338; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.8 Recommendations for remediation of fungal growth are
beyond the scope of this guide.
1.1 This guide provides a compendium of information and a
menu of options for assessment of fungal growth in buildings, 1.9 This guide is not intended to supersede any government
but does not recommend a specific course of action. Due to the regulations governing the assessment of fungal growth in
wide variety of fungal problems affecting buildings and their buildings.
occupants, and the wide variety of buildings, it is not possible
1.10 This standard does not purport to address all of the
to describe a set of uniform steps that will always be performed
safety concerns, if any, associated with its use. It is the
during an assessment (that is, a standard practice); therefore the
responsibility of the user of this standard to establish appro-
user of this guide must decide which steps are appropriate for
priate safety, health, and environmental practices and deter-
a given situation or building.
mine the applicability of regulatory limitations prior to use.
1.11 This international standard was developed in accor-
1.2 This guide is specific to fungal growth, which is only
dance with internationally recognized principles on standard-
one potential problem in a building environment. It may be part
ization established in the Decision on Principles for the
of, but is not intended to take the place of, a comprehensive
Development of International Standards, Guides and Recom-
indoor air quality investigation.
mendations issued by the World Trade Organization Technical
1.3 This guide describes minimum steps and procedures for
Barriers to Trade (TBT) Committee.
collecting background information on a building in question,
procedures for evaluating the potential for moisture infiltration
2. Referenced Documents
or collection, procedures for inspection for suspect fungal
2.1 ASTM Standards:
growth, and procedures beyond the scope of a basic survey that
C755 Practice for Selection of Water Vapor Retarders for
may be useful for specific problems.
Thermal Insulation
1.4 Assessments for fungal growth may be useful wherever
C1699 Test Method for Moisture Retention Curves of Po-
fungal growth is suspected, excess moisture has been present
rous Building Materials Using Pressure Plates
or when there are concerns regarding potential fungal growth.
D653 Terminology Relating to Soil, Rock, and Contained
1.5 Periodic fungal assessment in buildings may be a
Fluids
component of preventative maintenance programs.
D4442 Test Methods for Direct Moisture Content Measure-
ment of Wood and Wood-Based Materials
1.6 This guide is applicable to buildings including residen-
E331 Test Method for Water Penetration of Exterior
tial (for example, single or multi-family), institutional (for
Windows, Skylights, Doors, and Curtain Walls by Uni-
example, schools, hospitals), government, public assembly,
form Static Air Pressure Difference
commercial (for example, office, retail), and industrial facili-
E547 Test Method for Water Penetration of Exterior
ties.
Windows, Skylights, Doors, and Curtain Walls by Cyclic
1.7 Recommendations for developing a sampling strategy or
Static Air Pressure Difference
methods for the collection and analysis of fungal samples are
E631 Terminology of Building Constructions
beyond the scope of this guide. For recommendations for
E1105 Test Method for Field Determination of Water Pen-
developing a sampling strategy, see Ref (1) , Chapter 10.
etration of Installed Exterior Windows, Skylights, Doors,
and Curtain Walls, by Uniform or Cyclic Static Air
This guide is under the jurisdiction of ASTM Committee D22 on Air Quality
Pressure Difference
and is the direct responsibility of Subcommittee D22.08 on Assessment, Sampling,
and Analysis of Microorganisms.
Current edition approved Jan. 1, 2023. Published February 2023. Originally
approved in 2010. Last previous edition approved in 2014 as D7338 – 14. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
DOI:10.1520/D7338-14R23. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
The boldface numbers in parentheses refer to a list of references at the end of Standards volume information, refer to the standard’s Document Summary page on
this standard. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7338 − 14 (2023)
E1186 Practices for Air Leakage Site Detection in Building ‘mildew’ are frequently used by laypersons when referring to
Envelopes and Air Barrier Systems various fungal colonization.
E1356 Test Method for Assignment of the Glass Transition
3.2.5 fungal spore, n—general term for a reproductive
Temperatures by Differential Scanning Calorimetry
structure in fungi. The spore is the structure that may be used
E2128 Guide for Evaluating Water Leakage of Building
for dissemination and reproduction, and may be resistant to
Walls
adverse environmental conditions.
E2270 Practice for Periodic Inspection of Building Facades
3.2.6 hypha, n—(pl. hyphae) tubular filament of fungal
for Unsafe Conditions
cells; the basic vegetative structure of the body of fungi
2.2 Non-ASTM Standards:
(excluding yeasts).
ANSI/GEI Standard MMS1001 Mold and Moisture Man-
3.2.7 fungal growth, n—vegetative portion of a fungus.
agement Standard for New Construction
3.2.8 infrared thermography, n—thermal imaging, also
called thermography, is the production of non-contact infrared,
3. Terminology
or “heat” pictures from which temperature measurements can
3.1 Definitions:
be made.
3.1.1 building envelope, n—the outer elements of a
3.2.9 remediation, n—to correct a problem. Related to
building, both above and below ground, which divide the
fungal contamination, remediation includes correcting the
external from the internal environments. Commonly included
water and moisture problems and the cleaning, removal, and/or
are exterior walls, windows, doors, roofs and subfloors. E631
replacement of mold-damaged or -contaminated materials.
3.1.2 bulk sample, n—piece or quantity of bulk material that
3.2.10 thermal bridging, n—a phenomenon that occurs
has been selected by some sampling process. D653
when heat is transferred at a substantially higher rate through
3.1.3 capillary action, n—(or capillary migration), of water,
a component, or assembly of components in a building
movement of water induced by the force of molecular attrac-
envelope, than through the surrounding envelope area.
tion (surface tension) between the water and the material it
contacts. E631
4. Summary of Guide
3.1.4 condensation, n—the process of converting a material
4.1 This guide presents a framework for locating and
in the gaseous phase to a liquid by decreasing temperature or
evaluating suspect fungal growth in buildings. Topics include
by increasing pressure, or both. E1356
background information, a basic assessment strategy and
3.1.5 exposure, n—contact with a chemical, biological,
additional or advanced procedures.
physical, or other agent over a specified time period. E1356
4.2 Components of a basic assessment strategy may include
3.1.6 moisture content, n—mass of water retained in the
(1) defining a scope of work, (2) collecting background
specimen divided by the dry mass of the specimen. C1699
information on the building and building systems, (3) formu-
3.1.7 soot, n—agglomerations of particles of carbon impreg-
lation of a hypothesis or hypotheses, (4) an on-site survey for
nated with tar, formed in the incomplete combustion of
fungi, moisture dynamics, and heating. ventilating and air
carbonaceous material. E1356
conditioning (HVAC) operation, and (5) documentation and
3.1.8 vapor retarder, n—a material or system that ad- reporting. Every component of the basic assessment shown
equately impedes the transmission of water vapor under below may be considered optional, since even some of the
specified conditions. E631 most basic steps may not be needed for certain well-defined
situations.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 boroscope, n—device for internal inspection of diffi- 4.3 When the information from the basic assessment is
cult access locations such as wall cavities. Its long narrow tube
insufficient to support decision-making, additional procedures
contains a telescope system with a number of relay lenses. for a follow-up study may include: (1) characterizing site
Light is provided via the optical path or fiber bundles. moisture in greater detail to assist in locating suspect fungal
growth and controlling excess moisture; (2) accessing surfaces
3.2.2 effloresce, v—process by which water leaches soluble
likely to harbor hidden fungal growth; and/or (3) sampling if
salts out of concrete or mortar for surface deposit. Also
necessary to test a specific hypothesis.
efflorescence, n, the name for these deposits.
3.2.3 enzyme activity, n—measure of the quantity of active
5. Significance and Use
enzyme present. Enzyme activity is essential to metabolism.
5.1 This guide presents options for a systematic assessment
Specifically, beta-N-acetylhexosaminidase (NAHA) is an en-
of fungal growth in buildings.
zyme present in all filamentous fungi, the measurement of
which has been shown to be directly proportional to the amount
5.2 This guide allows for site-specific flexibility and profes-
of fungal biomass (see (2, 3).
sional judgment in the choice of assessment procedures. It may
3.2.4 fungus (s), fungi (pl.), n—eukaryotic, heterotrophic, not be necessary to perform in its entirety the basic assessment
absorptive organisms that usually develop a rather diffuse, presented below to resolve a particular problem, for example,
branched, tubular body (that is, network of hyphae) and usually where fungal growth is localized and the source and extent of
reproduce by means of spores (4). The terms ‘mold’ and moisture is readily observable.
D7338 − 14 (2023)
5.3 Conversely, no matter how comprehensive the survey, 6.2.1.4 Sustained elevated humidity;
all fungal growth may not be identified or located in a fungal 6.2.1.5 Wicking due to capillary action from wet material.
assessment.
6.2.2 Whether or not fungal growth actually occurs is
dependent on:
5.4 Material removal or destructive investigation may be
6.2.2.1 Substrate porosity (for example, materials such as
needed to access suspect surfaces.
carpet tack strip and conventional drywall are highly
5.5 Using the procedures described in this guide, the inves-
susceptible),
tigator may have obtained the data necessary to suggest
6.2.2.2 Moisture resistance (for example, some drywall,
specific recommendations, for example, how to remediate the
gypsum plaster and sheathing products are modified to resist
observed fungal growth, or how to prevent further fungal
moisture or to limit water storage and/or are treated with an
growth, but those recommendations are beyond the scope of
anti-microbial agent),
this guide.
6.2.2.3 Moisture duration (for example, leaks which are
5.6 Precautions may be needed to protect the assessor and
single events or intermittent may dry before fungal growth is
building occupants where access may disturb fungal growth. initiated; elevated humidity typically does not trigger fungal
growth unless it is sustained),
5.7 It is the user’s responsibility to protect information that
6.2.2.4 Air circulation and dehumidification (for example,
may be considered confidential, or private, or both, in accor-
moisture may remained trapped when sealed behind
dance with project contract, corporate protocol, or local, state,
baseboards, attached furniture or vapor barriers).
and federal regulations, or a combination thereof.
6.3 Detection of Fungal Growth:
5.8 It may be necessary to enlist other disciplines or trade
6.3.1 Fungus grows on an appropriate substrate. Fungal
expertise to assist in some steps of the assessment, but
growth is associated with biodegradable building materials (for
recommendations of when to enlist and whom to enlist are
example, paper covered gypsum wallboard, wood, ceiling
beyond the scope of this guide.
tiles). It will not grow on inorganic materials (for example,
masonry, concrete, gypsum plaster, stone, glass, ceramic tiles,
6. Background Information
grout) except where dust, dirt, grease or oil is present. It
6.1 Fungal Biology:
usually appears on surfaces which are wet or were previously
6.1.1 Fungal Growth—Fungi constitute over 25 % of the
wet. Fungal growth may pre-exist on wood surfaces not subject
earth’s biomass and are naturally present in every indoor and
to water damage on-site. For example, wood used for building
outdoor environment. Fungal spores (small propagules emitted
materials often becomes stained during tree growth or milling
from surface growth) are ubiquitous in air and settled dust.
6.3.2 Fungal growth may be detected by simple visual
Fungal growth requires sufficient available moisture that is
inspection. Fungal growth may appear as raised, powdery
sustained for a sufficient time, a suitable food source/substrate,
deposits, rings or colored spots which may be black, gray,
and a favorable range of temperature and pH. Both active and
white, green, red, resembling cotton, velvet, leather, or powder.
inactive (past) growth are termed “colonization” (5, 6, 7).
When rubbed, dried fungal growth tends to spread or smear as
Fungi can become dormant only to resume growth again in
a powder.
response to changing environmental conditions (for example,
6.3.3 Discoloration is not necessarily fungal growth. The
during periodic moisture intrusions).
following surface markings should not be categorized as
6.1.2 Fungal Spore Production—Fungal spores are pro-
suspect fungal growth: yellow/brown water stains, scuffs, soot,
duced during active growth, but may be released into the air
dye, dust, ghosting (dust deposits form an outline on a cool
either during active growth or dormancy. Where fungal growth
surface), efflorescence, adhesives, and other residues of
is located behind a wall, wall covering, ceiling, or carpet,
occupancy, maintenance, or construction.
spo
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