Mold in a Phase I

The site visit finds growth on walls, ceilings or other surfaces, or the user asks whether the Phase I covers mold. The standard lists mold or microbial growth conditions among its non-scope considerations, and unlike its entries for asbestos, lead-based paint and indoor air quality, that entry carries no condition about releases (E1527-21, 13.1.5.1, 13.1.5.7, 13.1.5.9, 13.1.5.11). How mold figures in the report depends on four things: what the user has asked for, whether what was seen is a feature the site visit must describe, whether hazardous substances or petroleum products are involved at all, and what business risk the user wants weighed.

What the answer turns on

What the user has asked for. No assessment of a non-scope consideration is required for all appropriate inquiries as the practice defines them, whether or not the user chooses to look into it (E1527-21, 13.1.2). A service beyond the practice should be weighed against the property and the reasons for the assessment, and agreed before the assessment begins (E1527-21, 1.4). The standard's appendixes are nonmandatory. The user questionnaire in one of them asks for the scope of services wanted, including any considerations beyond the practice (E1527-21, X3.1.4). The practice includes no testing or sampling of air or building materials (E1527-21, 7.4). The non-scope appendix says no federal regulation or standard governs airborne mold, and points to a separate ASTM guide for investigating and assessing mold (E1527-21, X6.9.1).
Whether what was seen is a site visit feature. Stains or corrosion on floors, walls or ceilings are among the features the site visit looks for and the report describes, but that item leaves out staining from water (E1527-21, 9.4, 9.4.20). Strong, pungent or noxious odors and their sources are another (E1527-21, 9.4.13). The non-scope appendix says molds need a food source and moisture to grow (E1527-21, X6.9). Establish what the growth or staining is on, and whether anything besides water caused it.
Whether hazardous substances or petroleum products are involved. The definition of a recognized environmental condition (REC) needs hazardous substances or petroleum products present or likely present at the subject property owing to a release or likely release to the environment, or present where conditions pose a material threat of one (E1527-21, 3.2.73). A hazardous substance is one the federal cleanup law defines as such (E1527-21, 3.2.36). The non-scope appendix says molds can produce toxic substances called mycotoxins and give off volatile compounds; the standard does not say whether either is a hazardous substance (E1527-21, X6.9). Indoor air quality unrelated to a release is a separate non-scope consideration, and the same appendix lists wet or damp carpet among the sources of indoor air pollution (E1527-21, 13.1.5.7, X6.8). Establish whether the same area holds anything the site visit items cover, such as containers, drains, or stains from something other than water (E1527-21, 9.4.11, 9.4.20, 9.4.21).
What business risk the user wants weighed. A business environmental risk (BER) is one that can materially affect the business tied to the current or planned use of the property, and need not be something the practice requires investigating (E1527-21, 3.2.11). The non-scope appendix lists among the business risks of mold in a building claims by tenants and occupants over exposure, abatement costs, lost tenants, bad publicity and lower property value, and says some jurisdictions' general disclosure rules for real estate sales may reach significant mold contamination (E1527-21, X6.9.1, X6.9.2).

The records that bear on it

Site visit. Inside buildings the site visit covers accessible common areas; places where hazardous substances or petroleum products are now, or may once have been, stored, used or disposed of; boiler rooms; maintenance and repair areas; and a sample of occupant spaces chosen as representative (E1527-21, 9.2.3). Conditions above ceilings, under floors or behind walls need not be identified (E1527-21, 9.2.4.2). Photographs are required of what indicates a REC or a de minimis condition; others are at the professional's discretion (E1527-21, 12.3).
Interviews. Interview questions cover the site visit features, current and past (E1527-21, 10.2). At a multifamily residential property, residential occupants need not be interviewed; where it has non-residential uses, those occupants should be, on the standard's criteria (E1527-21, 10.5.2.1, 10.5.2.2).
Documents. The standard's list of helpful documents names no mold or moisture report; it includes environmental site assessment reports, site investigation reports and risk assessments (E1527-21, 10.8.1).

What the federal rule says

The inquiry rule (40 CFR part 312) does not mention mold. The first thing it has the professional's written report include begins:

An opinion as to whether the inquiry has identified conditions indicative of releases or threatened releases of hazardous substances

40 CFR 312.21(c)(1), edition revised as of July 1, 2025

How it is written up

Where the user has engaged a mold service, it appears in the report only as the terms of engagement specify, and additions to the practice are listed (E1527-21, 12.10, 12.11). The suggested format in Appendix X5 gives it a non-scope services section, stated as agreed, and lets BERs that go with it be discussed in the Findings, Opinions and Conclusions (E1527-21, X5.7, X5.8, X5.9).

Where no mold service was engaged, the body of the standard does not say whether growth seen on the site visit is mentioned; the non-scope appendix says putting any non-scope item in the report is for the user to decide (E1527-21, X6, introduction). The Conclusions list RECs, controlled RECs and significant data gaps (E1527-21, 12.7).

Where the same area shows a feature the professional judges may indicate hazardous substances or petroleum products present or likely present at the subject property, it is a finding, and the opinion gives the reasoning for or against each class it pertains to (E1527-21, 12.5, 12.6). Where the professional concludes a release has left them present or likely present, the opinion gives the grounds. Unless judged a de minimis condition or a historical REC, the REC is listed in the Conclusions, and the professional should give an opinion on additional investigation, if any (E1527-21, 3.2.20, 3.2.39, 12.7, 12.8). Where the professional concludes otherwise, the opinion gives its reasoning on the same facts (E1527-21, 12.6).

Observation of occupant spaces, of which the site visit is to see a representative sample, may be what cannot be had (E1527-21, 9.2.3). Required information that good faith efforts could not obtain is a data gap, significant if it affects the ability to identify a REC: named in the Findings with the sources consulted, discussed in the Opinions and listed in the Conclusions (E1527-21, 3.2.19, 3.2.78, 12.5.1, 12.6.2, 12.7).

This page is general reference for environmental professionals. It does not classify any property. ASTM E1527-21 is the standard and is not reproduced here; the judgment of the environmental professional on the facts governs.