Why Insurance Companies Are Canceling Policies Over Roof Algae and Mold

TCS Blog

In recent years, homeowners across California have been receiving alarming letters from their insurance carriers: notices of non-renewal or outright cancellation of their homeowners insurance policies. The surprising culprit in many cases? Visible algae, mold, moss, or black streaks on the roof.

At TCS Insurance Brokers, we’ve seen this trend firsthand while helping clients navigate tough insurance markets. What starts as seemingly harmless dark staining (often caused by Gloeocapsa magma algae) can signal “neglect” to insurers, who view it as a red flag for potential water damage, rot, leaks, or premature roof failure. Insurers are increasingly using drone surveillance, satellite imagery, and aerial inspections to spot these issues remotely—sometimes flagging roofs that look “dirty” or aged, even if they’re structurally sound.

Why Algae and Mold Trigger Insurance Action

Insurance companies underwrite policies based on risk. A roof with buildup isn’t just an eyesore; it can:
• Trap moisture, accelerating shingle deterioration or wood rot underneath.
• Lead to leaks, interior mold growth, and expensive damage.
• Indicate overall home maintenance neglect, raising the likelihood of future claims for the insurer.

Common triggers include:

• Black streaks or dark staining from algae (often cosmetic but mistaken for damage).
• Green/black moss or lichen growth.
• Mold/mildew visible in shaded or north-facing areas.

When flagged, carriers may:

• Increase premiums significantly.
• Exclude roof coverage.
• Issue non-renewal notices (common in hard markets like California’s).
• Cancel policies outright if the issue isn’t addressed promptly.

Only a handful of our client’s experienced a bad situation because we pro-actively approached this shift in the market. But we’ve reviewed numerous cases of new clients where the homeowners were caught off guard—sometimes over minor cosmetic issues that low-resolution aerial photos misinterpreted as major damage and that their agent did not catch in time to remedy. The result? Scrambling to find new coverage, often at much higher rates.

The Good News: Many Cases Are Preventable

The key is proactive maintenance. Regular roof cleaning removes algae, moss, and debris before they become an insurance headache. Importantly, insurers often reverse non-renewals if you provide proof of professional cleaning and a clean roof condition report or photos. Something that your insurance pro should be helping you with if you are in this situation.

Traditional high-pressure washing can damage shingles, but a gentler approach works best for roofs.

We recommend our clients in the Central Valley and surrounding areas use soft washing services. This low-pressure method uses eco-friendly, biodegradable cleaning solutions to safely eliminate algae, mold, and grime without harming shingles or voiding warranties.

One trusted local provider we often point clients toward is Soft Washing Grime Busters (https://softwashinggrimebusters.com). They specialize in soft washing for roofs, house exteriors, and more—using professional-grade equipment and solutions that effectively sanitize and prevent regrowth. As a Central Valley-based company (serving areas like Tracy, Turlock, and beyond), they’re familiar with our region’s climate challenges, like shaded roofs prone to moisture buildup. Plus, they know what insurers are looking for and with their help we have saved countless policyholders from being cancelled!

A professional soft wash can:

• Restore your roof’s appearance quickly.
• Extend its lifespan.
• Provide documentation (photos, invoices, or condition reports) to submit to your insurer—often enough to reinstate or maintain coverage.

Steps to Take If You’re Facing a Non-Renewal

1. Contact your insurer immediately — Ask for specifics on the issue and whether cleaning (vs. full replacement) could resolve it. – If you have a good agency on your side, like us, we would be doing this for you.
2. Get a professional inspection and cleaning — Document everything. – Use a professional company and avoid the headaches and injuries that come with doing it yourself.
3. Submit proof — Photos, reports, and service receipts can turn things around. – Again, your insurance professional should be helping you with this.
4. Review your policy — Work with your broker to explore options if needed. – If your provider is failing you, please reach out to us, we would be happy to assist you!

At TCS Insurance Brokers, we’re here to help California homeowners protect their assets in a challenging insurance landscape. Whether it’s shopping for better coverage, advising on risk management, or connecting you with reliable service providers, our team has you covered.

Concerned about your roof or policy? Contact us today for a no-obligation review or quote. Don’t wait for that cancellation letter—proactive steps today can save you stress and money tomorrow.

Blog post written by Domingo Ramos, CA Lic. 0F53636, National Producer Number 9071660

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Why Insurance Companies Are Canceling Policies Over Roof Algae and Mold – And How to Protect Your Coverage

Why Algae and Mold Trigger Insurance Action

The Good News: Many Cases Are Preventable

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