A Renter’s Guide to Mold: What Tenants & Landlords Must Know in California

Author: Bay Area Pros

Mold problems in California rentals are far more common than many people realize. Between coastal moisture, fog, rainstorms, plumbing leaks, and aging housing stock, mold can appear quickly—often before anyone notices a smell or sees visible growth. For renters and landlords alike, understanding rights, responsibilities, and when to bring in a third-party mold inspector is essential for protecting health, safety, and property value.

This guide explains California’s mold laws, what each party must do, and how independent mold inspection helps resolve disputes with reliable, neutral evidence.

Understanding California Mold Laws

California’s housing laws are very clear: landlords must provide safe and habitable housing, and this includes addressing mold hazards.

Two key regulations apply:

California Health & Safety Code §17920.3

This code defines mold as a factor that can make a property substandard if it endangers the health of occupants.

California Senate Bill 655 (SB 655)

SB 655 mandates that landlords are responsible for maintaining mold-free living conditions—except when the tenant’s own poor housekeeping or negligence causes the mold.

Together, these laws establish mold as a habitability issue that must be addressed promptly and professionally.

Tenant Rights: What Renters Can Expect

1. The Right to a Mold-Safe Home

Every renter is entitled to live in a home that is free from dangerous or excessive mold growth. If mold is found, the landlord must take reasonable steps to remove it and fix the underlying moisture problem.

2. The Right to Request Repairs

Tenants can submit written repair requests for:

  • Visible mold
  • Musty odors
  • Water leaks or plumbing failures
  • Dampness or condensation issues
  • Recurring moisture problems

Landlords must respond promptly and are prohibited from ignoring legitimate health and safety concerns.

3. The Right to Avoid Retaliation

It is illegal for a landlord to raise rent, reduce services, or evict a tenant as retaliation for reporting mold problems or requesting repairs.

4. The Right to a Professional Evaluation

Tenants may hire a third-party mold inspector—such as Bay Area Mold Pros—to document the issue, especially if:

  • The landlord disputes the presence of mold
  • Repairs are delayed
  • The tenant is experiencing health symptoms
  • Mold keeps returning
  • There is no visible mold, but musty odors persist

A neutral inspection provides factual evidence to support repair requests or legal claims if necessary.

Landlord Responsibilities: What the Law Requires

Landlords must repair and mitigate:

1. Maintain Habitable Living Conditions

  • Roof leaks
  • Plumbing leaks
  • Poor ventilation
  • Water intrusion
  • Dampness from building defects
  • Mold caused by structural or maintenance issues

It is not enough to simply clean visible mold—landlords must address the source of moisture.

2. Respond Promptly to Mold Complaints

California law requires landlords to act within a reasonable timeframe. Failing to respond may expose them to liability, especially if the mold worsens or causes health issues.

3. Hire Qualified Professionals

If mold appears significant or keeps returning, landlords must hire trained professionals for inspection and remediation.

4. Provide Proper Notice for Entry

Landlords must give 24-hour notice before entering the rental unit to investigate mold or perform repairs.

When Mold Is the Tenant’s Responsibility

Landlords are not responsible for mold caused by:

  • Poor housekeeping
  • Failure to use ventilation
  • Tenant-created leaks
  • Allowing water spills to sit
  • Blocking airflow with clutter
  • Running humidifiers excessively

However, even in these cases, the landlord may still need to fix the moisture problem once identified—while charging the tenant for repairs if applicable.

When to Get a Third-Party Mold Inspection

Independent mold testing is recommended when:

You smell a musty odor but can’t find the source

Hidden mold is extremely common behind walls, under flooring, or around plumbing leaks.

The landlord insists there is no mold

Professional testing provides scientific evidence, not guesswork.

Mold keeps coming back after cleaning

Recurring mold almost always indicates unresolved moisture issues.

A tenant is experiencing unexplained allergies or respiratory symptoms

Air testing can reveal elevated mold spore levels.

You’re preparing for mediation or legal action

A neutral, lab-verified report is far stronger than photos or complaints.

There was flooding, heavy rain intrusion, or a plumbing leak

Post-water-damage testing helps confirm whether mold spread behind walls.

You’re moving into a new rental

A pre-move-in inspection provides peace of mind—especially in older Bay Area buildings.

Bay Area Mold Pros offers unbiased inspections only—we do not perform mold remediation, which eliminates conflict of interest and ensures accurate reporting.

The Value of Neutral, Third-Party Mold Reports

Landlord-tenant mold disputes can quickly become emotional. A professional inspection removes guesswork and provides:

  • Photo documentation
  • Moisture readings
  • Thermal imaging findings
  • Air and surface lab results
  • Written conclusions
  • Recommended next steps

Because the report is unbiased, both tenants and landlords can rely on it to determine the most appropriate course of action.

Protect Your Safety and Your Rights

Whether you’re a tenant concerned about your health or a landlord trying to stay compliant, mold issues should never be ignored. Early detection saves money, protects buildings, and prevents long-term health effects. For a clear, independent assessment, schedule a mold inspection with Bay Area Mold Pros.

Call (650) 762-6228 or request an appointment through our website today.