INDUSTRY RESEARCH
Mold Statistics 2026: 3.9 Million U.S. Homes Report Mold
A fresh analysis of 2023 American Housing Survey microdata covering reported mold, leaks, renters, older homes, and Northeast housing risk
Published July 2026 · Updated July 2026 · Northeast Mold Experts Research Team
Key Findings
Most household mold articles still quote older American Housing Survey figures. For this 2026 update, Northeast Mold Experts analyzed the latest available national microdata from the 2023 American Housing Survey Public Use File, released by HUD and the U.S. Census Bureau in September 2024.
- 3.9 million occupied U.S. homes reported mold in at least one room in the 2023 AHS, equal to 2.9% of occupied households.
- 20.5 million occupied homes reported an inside or outside leak, equal to 15.4% of occupied households.
- 55% of households that reported mold also reported a leak, reinforcing the practical link between moisture control and mold prevention.
- Renters reported mold at 2.7 times the owner rate: 5.0% of renter households versus 1.8% of owner households.
- Pre-1980 homes reported mold at more than twice the rate of post-2000 homes: 3.6% versus 1.5%.
- Bathrooms were the most common mold location, with 1.86 million households reporting bathroom mold.
- The Northeast was slightly above the national average: New England and the Middle Atlantic divisions combined reported roughly 730,000 mold households, or about 3.1% of occupied households.
How to cite this data:
Northeast Mold Experts. “Mold Statistics 2026: 3.9 Million U.S. Homes Report Mold.” Published July 2026. Analysis of the 2023 American Housing Survey National Public Use File.
Citation URL: https://northeastmoldexperts.com/mold-statistics-2026/
Why This Update Matters
The U.S. Census Bureau and HUD run the American Housing Survey every two years, but many popular mold resources still use older 2019 or 2021 numbers. For example, This Old House's household mold guide still references 2019 and 2021 AHS mold and leak statistics even though the 2023 public-use microdata is now available.
That does not make the older articles useless. It does mean homeowners, renters, journalists, and property managers can now work from fresher figures. The 2023 AHS is especially useful because it does not only ask whether mold was present. It also includes room-level mold variables, leak variables, tenure, age of home, household composition, and Census division, which makes a more practical analysis possible.
Methodology
Northeast Mold Experts analyzed the 2023 AHS National Public Use File flat CSV. We limited the analysis to occupied housing units and applied the household weight variable WEIGHT unless otherwise noted. A home counted as reporting mold if any of the six room-level mold variables were marked yes: kitchen, bathroom, bedroom, basement, living room, or other room.
Leakage counted as any reported inside or outside leak in the AHS leak variables. Regional estimates use Census division, not state-level modeling. That matters for Northeast Mold Experts because the service area spans New England, the Middle Atlantic, and nearby Mid-Atlantic states that appear in the South Atlantic division.
This is a self-reported housing survey, not an on-site mold inspection program. The numbers should be read as reported household conditions, not lab-confirmed mold prevalence.
Data source for the tables: Northeast Mold Experts analysis of the U.S. Census Bureau 2023 American Housing Survey National Public Use File. HUD and the Census Bureau announced the 2023 AHS summary tables and public-use microdata release on September 25, 2024.
National Mold and Leak Numbers
| 2023 AHS measure | Weighted households | Share of occupied households |
|---|---|---|
| Occupied U.S. households | 133.2 million | 100.0% |
| Mold in at least one room | 3.9 million | 2.9% |
| Mold in two or more rooms | 747,000 | 0.6% |
| Any inside or outside leak | 20.5 million | 15.4% |
| Both mold and a leak | 2.1 million | 1.6% |
Source: Northeast Mold Experts analysis of occupied households in the 2023 American Housing Survey National PUF, using household weight WEIGHT. Release details: HUD USER 2023 AHS release notice.
The biggest practical takeaway is not only that 3.9 million homes reported mold. It is that more than half of mold-reporting households also reported a leak. That lines up with EPA guidance that the central rule of mold control is moisture control: clean up mold, fix the water problem, and dry wet materials quickly.
Where Mold Shows Up Most Often
The AHS asks about mold in specific rooms. Bathrooms were the most common location, followed by bedrooms and kitchens.
| Reported mold location | Weighted households | Share of occupied households |
|---|---|---|
| Bathroom | 1.86 million | 1.4% |
| Bedroom | 909,000 | 0.7% |
| Kitchen | 736,000 | 0.6% |
| Other room | 655,000 | 0.5% |
| Living room | 592,000 | 0.4% |
| Basement | 389,000 | 0.3% |
Source: Northeast Mold Experts analysis of room-level mold variables in the 2023 American Housing Survey National PUF: kitchen, bathroom, bedroom, basement, living room, and other room.
Bathrooms being first is not surprising. Showers, poor exhaust, condensation, wet towels, and plumbing penetrations all create moisture opportunities. The basement figure may look low to Northeast homeowners, but remember that the national denominator includes homes without basements.
Renters Report Mold More Often Than Owners
| Tenure | Occupied households | Mold households | Mold rate |
|---|---|---|---|
| Owner-occupied | 86.9 million | 1.6 million | 1.8% |
| Renter-occupied | 46.4 million | 2.3 million | 5.0% |
Source: Northeast Mold Experts analysis of tenure and room-level mold responses in the 2023 American Housing Survey National PUF.
Renters reporting mold at nearly 2.7 times the owner rate is one of the most useful outreach angles in this dataset. It creates a strong reason to pitch landlord, property management, renter-health, and housing-quality publications with a fresh statistic instead of a generic mold-prevention article.
A prior peer-reviewed housing-health study using 2019 AHS data also found that dampness and mold were among the more common housing-related environmental health domains. The difference here is that the new analysis isolates the latest self-reported room-level mold variables from the 2023 survey and adds current leak, tenure, age, and regional cuts.
Older Homes Still Carry More Mold Risk
| Year built group | Occupied households | Mold households | Mold rate |
|---|---|---|---|
| Built before 1980 | 66.7 million | 2.4 million | 3.6% |
| Built after 2000 | 32.8 million | 498,000 | 1.5% |
Source: Northeast Mold Experts analysis of year-built and room-level mold variables in the 2023 American Housing Survey National PUF.
Older homes are not automatically moldy, and newer homes are not automatically safe. But older housing often has more accumulated maintenance history: aging roof assemblies, foundation seepage, old plumbing, retrofitted insulation, and imperfect ventilation. That matters in the Northeast and Mid-Atlantic, where older housing stock is common.
Northeast and Mid-Atlantic Mold Rates
The AHS public-use file supports Census division analysis. New England and the Middle Atlantic divisions were both slightly above the national mold-reporting rate. The South Atlantic, which matters for Maryland and Delaware context, was close to the national rate.
| Census division | Occupied households | Mold households | Mold rate |
|---|---|---|---|
| New England | 6.2 million | 193,000 | 3.1% |
| Middle Atlantic | 17.1 million | 538,000 | 3.2% |
| South Atlantic | 28.9 million | 870,000 | 3.0% |
| United States | 133.2 million | 3.9 million | 2.9% |
Source: Northeast Mold Experts analysis of Census division and room-level mold variables in the 2023 American Housing Survey National PUF. Public-use geography supports Census division analysis; this is not a state-level estimate.
For homeowners in New Jersey, New York, Pennsylvania, Connecticut, Delaware, and Maryland, the data points to a familiar pattern: older housing, basements, humidity, storm events, and delayed leak repairs all belong in the same risk conversation.
What the Numbers Do Not Prove
These figures do not prove that one state or city is moldier than another. They also do not tell us whether a particular home requires professional remediation. The AHS is powerful for national housing trends, but mold decisions in a real building still depend on visible growth, moisture source, area affected, material type, occupant health risk, and whether hidden moisture remains.
That is why CDC and NIOSH guidance is cautious about routine air sampling. NIOSH notes that visual inspections and musty odors can be more reliable than short-term air samples for dampness and mold assessments. CDC also says homeowners do not need to know the species of mold before removing it; the moisture problem still needs to be corrected.
Practical Takeaways
- For homeowners: Treat leaks as time-sensitive. EPA guidance says wet materials should be dried within 24 to 48 hours where possible to prevent mold growth.
- For renters: Document visible mold, leaks, odors, and repair requests in writing. The renter mold rate in the latest AHS data is meaningfully higher than the owner rate.
- For landlords and property managers: Bathrooms, recurring leaks, older units, and tenant turnover are the highest-value inspection points.
- For journalists and publishers: The most current national AHS mold statistic is approximately 3.9 million occupied households reporting mold in 2023, not the older 2019 or 2021 figures still repeated across the web.
Sources
- U.S. Census Bureau: 2023 American Housing Survey Public Use File
- HUD USER: 2023 AHS Summary Table Estimates and Public Use Files Release
- EPA: A Brief Guide to Mold, Moisture and Your Home
- EPA: Ten Things You Should Know About Mold
- CDC: Mold
- NIOSH: Mold, Testing, and Remediation
- Environmental Health: Housing and Environmental Quality Index using 2019 AHS
- This Old House: What To Know About Household Mold
About Northeast Mold Experts: Northeast Mold Experts helps property owners in New Jersey, New York, Pennsylvania, Connecticut, Delaware, and Maryland understand mold risk and get connected with appropriate mold inspection and remediation resources.