Under California Health and Safety Code § 17920.3(a)(13), visible mold growth, as determined by a health officer or code enforcement officer, can make a rental a substandard building, and a unit described in § 17920.3 is untenantable under Civil Code § 1941.1. Landlords must also give prospective tenants the California Department of Public Health (CDPH) mold booklet before signing (H&S § 26148). The statutes on this page do not set a cleaning method for ordinary mold, so the practical job is to find the moisture source, fix it and document the work.

The short version

  • Visible mold growth is listed as a substandard condition in H&S § 17920.3(a)(13), and dampness of habitable rooms in (a)(11), when they reach a level that endangers occupants.
  • Minor mold on surfaces that collect moisture as part of their normal use (for example, a shower) is excluded from (a)(13).
  • Give the CDPH booklet, Information on Dampness and Mold for Renters in California, to prospective tenants before the lease is signed (§ 26148; required since January 1, 2022 per CDPH).
  • H&S § 26147, which would require disclosing known mold above exposure limits, is not in effect because CDPH has not adopted those limits.
  • Tenants must keep their space clean and use fixtures properly (Civil Code § 1941.2).
  • A good-faith complaint about tenantability, such as mold, can start the 180-day retaliation bar for a tenant who is not in default on rent (Civil Code § 1942.5(a)).

When mold becomes a legal problem

Section 17920.3 declares a building substandard when a listed condition exists "to an extent that endangers the life, limb, health, property, safety, or welfare of the occupants" or the public. The items that matter most for mold:

SubsectionCondition
§ 17920.3(a)(11)"Dampness of habitable rooms"
§ 17920.3(a)(13)"Visible mold growth, as determined by a health officer or a code enforcement officer", excluding mold that is minor and found on surfaces that can accumulate moisture as part of their properly functioning and intended use
§ 17920.3(g)(2)Deteriorated or ineffective waterproofing of exterior walls, roofs, foundations or floors, including broken windows or doors
§ 17920.3(a)(7)Lack or improper operation of required ventilating equipment

CDPH puts it plainly: "As of January 1, 2016, mold is also a condition that makes a home substandard in California. The owner of a rental property cited as substandard by a local (city or county) code inspector is required to repair the substandard condition."

If a public officer inspects, gives the landlord written notice to repair, and the condition stays unabated 35 days later without good cause (and the tenant did not cause it), Civil Code § 1942.4 bars the landlord from demanding or collecting rent, raising rent or serving a 3-day notice to pay or quit. The full repair and remedy rules are on the habitability and repairs page.

The mold disclosure

California requires the CDPH booklet, not a mold inspection. H&S § 26148 requires residential landlords to give prospective tenants a CDPH consumer booklet on the health risks of mold "prior to entering the rental or lease agreement". CDPH states that the requirement has applied since January 1, 2022, and that the booklet, Information on Dampness and Mold for Renters in California, is the one to use. A Spanish version is on the same CDPH page.

The other mold statute, H&S § 26147, would require written disclosure of known mold above permissible exposure limits. It is written into law but is not in effect, because CDPH has not adopted those limits; CDPH says the evidence did not support science-based limits for indoor mold and that this "remains the CDPH position to date." The landlord also does not have to test. Other lease disclosures are on the required lease disclosures page.

What to do when mold is reported

None of the statutes on this page prescribes how ordinary, non-disaster mold must be cleaned. CDPH's position is that "indoor dampness, water intrusion, or fungal growth should always be eliminated in a safe and efficient manner." A practical sequence:

  1. Log the report and respond quickly. Treat it like any maintenance request, with written notice for entry under Civil Code § 1954.
  2. Look for the water. Mold follows moisture. Check for roof or window leaks, plumbing drips, condensation, a failed exhaust fan or a blocked dryer vent.
  3. Fix the source first. Cleaning without stopping the moisture usually means the mold returns.
  4. Clean or remove affected materials. For small areas this may be routine cleaning; for larger areas, or where materials are soaked, consider hiring a remediation contractor.
  5. Dry the area fully and check it again after a few weeks.
  6. Document everything. Before-and-after photos, the cause found, the work done and invoices.
  7. Tell the tenant in writing what was found and done, and how to report a recurrence.

After a declared disaster, mold is one of the hazards a landlord must mitigate under Civil Code § 1941.8, following any government cleaning protocols and using licensed remediation companies where required. See emergency repairs.

If the work truly requires the tenant to move out for at least 30 consecutive days, abating hazardous materials such as mold can be part of a "substantial remodel" just cause under Civil Code § 1946.2(b)(2)(D). That route has strict conditions, including the notice contents, a copy of the permits (or a signed contractor contract for permit-free abatement) and one month's rent in relocation assistance; it is not a shortcut for ordinary repairs.

Tenant duties

Civil Code § 1941.2 requires the tenant to keep their part of the premises clean and sanitary, dispose of garbage properly, and properly use and operate electrical, gas and plumbing fixtures. The landlord's repair duty does not arise if the tenant's substantial violation of those duties substantially contributes to the problem. In practice, that makes everyday habits matter: running the bathroom fan, wiping condensation, and reporting leaks right away.

For owners

Include the CDPH booklet in every lease package. Inspect for leaks during turnover, keep gutters and exhaust fans working, and act on reports quickly; a good-faith complaint about mold can start the 180-day bar on retaliation in § 1942.5(a), covered on the retaliation, harassment and lockouts page. For coastal properties, the coastal maintenance guide has seasonal checks.

For renters

Report leaks, water stains and mold growth in writing, with photos, as soon as you see them. Ventilate bathrooms and kitchens, and do not paint over mold. If a reported problem is not addressed, you can contact your city or county code enforcement office, which can inspect and cite substandard conditions. A deposit deduction for cleaning is limited to returning the unit to its move-in level of cleanliness (Civil Code § 1950.5(b)(3)).

Local rules

Some California cities add rules on top of state law, such as local just-cause, relocation or rental registration requirements, so check your city's code; local code enforcement offices also handle substandard-housing inspections. Coronado has no local rent-control or just-cause ordinance as of October 2026 (based on a review of its code's contents).

Frequently asked questions

Is mold a habitability issue in California?

It can be. Visible mold growth determined by a health officer or code enforcement officer is a substandard condition under H&S § 17920.3(a)(13) when it endangers occupants, and Civil Code § 1941.1 treats a unit described in § 17920.3 as untenantable. Minor mold on surfaces that normally get wet, such as a shower, is excluded.

Do California landlords have to give tenants a mold disclosure?

Yes, in the form of the CDPH booklet. H&S § 26148 requires giving prospective tenants the booklet before the lease is signed, and CDPH says this has been required since January 1, 2022. The separate duty in § 26147 to disclose known mold above exposure limits is not in effect, because CDPH has not set those limits.

Does a landlord have to test for mold?

Section 26147, which is not in effect, states that the landlord need not test, and none of the other statutes on this page requires testing. What the law focuses on is visible mold and dampness, and the duty to repair substandard conditions.

Who pays to fix mold?

If mold makes the unit substandard or untenantable, the repair duty is the landlord's under §§ 1941 and 1941.1. If the tenant's substantial violation of the § 1941.2 duties substantially caused it, that duty does not arise. The cause matters, which is why documenting the moisture source is the first step.

Can a landlord evict a tenant to remove mold?

Only under the strict substantial-remodel rules of § 1946.2(b)(2)(D), which require work that cannot be done safely with the tenant in place and requires vacating for at least 30 consecutive days, plus specific notice contents and relocation assistance. Ordinary mold cleanup that does not require the tenant to vacate for 30 consecutive days does not meet that definition.

This is general information, not legal advice. Laws change; confirm the current text and your situation with a California attorney.

McKee Properties manages rentals from its Coronado office; contact us with questions about your property.

Sources

Verified October 19, 2026.

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