North Bay Mold Remediation connects San Anselmo homeowners, landlords, and tenants with local mold remediation contractors who track down the moisture, remove the growth, and dry the structure before it is closed back up. In this town, that often means looking under the house first.
Common requests include mold after water damage or flooding, crawl space mold remediation, musty smell and hidden mold investigation, and mold clearance testing once the work is done.
San Anselmo Creek and the town's flood history
Nearly all of San Anselmo sits in the Ross Valley watershed, and San Anselmo Creek, a branch of Corte Madera Creek, is its main waterway, with Sleepy Hollow Creek and Sorich Creek also running through town. The San Anselmo Historical Museum documents a long string of downtown floods, including 1925, 1943, 1955, 1969, January 1982, and December 31, 2005.
- January 1982: After more than 13 inches of rain on January 3 and 4, the Marin Independent Journal reported a river five feet deep running down San Anselmo Avenue.
- December 31, 2005: A Pineapple Express storm sent the creek over its banks in the early morning dark. More than four feet of water ran down San Anselmo Avenue, and the museum's account puts damage in town at about $30 million, affecting 140 businesses and 290 homes. Marin County's flood control district estimates the storm caused roughly $90 to $100 million in damage across the Ross Valley.
Floodwater is dirty water. Drywall, insulation, carpet, and pad that it soaks usually have to come out, not just dry out, and framing has to be cleaned and brought back to normal moisture before anything is rebuilt. The EPA advises drying water-damaged materials within 24 to 48 hours to prevent mold growth, which is hard to do across a whole neighborhood after a flood. That gap is where post-flood mold comes from.
Raised floors on the Flatlands
Many homes on the creek floodplain, the area the town calls the Flatlands, are built on raised foundations, a practice that goes back at least to 1920. Raising the floor keeps living space above shallow floodwater, but it leaves a crawl space that can take on water, hold damp soil, and stay humid well into spring.
In a crawl space, mold usually shows up on joists, subfloor sheathing, and the paper facing of insulation. Signs from inside the house include a musty smell that is strongest near floor registers or closets, cupping wood floors, and condensation on cold surfaces. The cleanup is only half the job. Without drainage, a vapor barrier, and a plan for water that gets in during storms, the growth tends to return.
Older housing and hillside homes
Census estimates put San Anselmo's median home construction year at about 1955, roughly a decade older than the Marin County median. The town grew after the 1906 earthquake, when San Francisco families turned summer houses into year-round homes, so a large share of houses here predate modern bathroom ventilation, vapor barriers, and moisture detailing.
- Older bathrooms without exhaust fans, or with fans vented into the attic.
- Original or patched plumbing that leaks slowly into wall cavities.
- Uphill sides of hillside homes, where soil sits against the foundation and lower-level walls.
Homes built before 1980 can contain asbestos in joint compound, textured ceilings, flooring, and duct wrap. If remediation means removing those materials, testing may be needed first, and asbestos work needs a contractor with CSLB asbestos certification or a C-22 license plus DOSH registration.
Rentals, licensing, and testing
Under California Health and Safety Code section 17920.3, as amended by SB 655, visible mold growth can make a rental substandard. Marin County Environmental Health Services inspects buildings of three or more rental units about every two years and on complaint, but it does not test for mold and does not cover single-family or condo rentals. Check with the Town of San Anselmo about which office takes a particular complaint. See rental mold inspection and remediation.
California has no mold license. Any job of $1,000 or more needs a CSLB-licensed contractor, and remediation firms commonly hold a B General Building or C-61/D-64 license. Verify at cslb.ca.gov. We recommend clearance testing by a firm that did not do the remediation.
On health, the EPA and CDC say mold can affect some people, especially those with allergies, asthma, or weakened immune systems. Their advice is to fix the moisture and remove the growth. See the EPA's mold guidance.
Seeing or smelling mold in a San Anselmo home? Call (415) 234-5586, or request an estimate from a local mold remediation contractor.
Mold remediation in San Anselmo
- Mold Remediation → Containment, removal, and cleanup of mold growth in homes and rentals, following the IICRC S520 approach, with the moisture source fixed first.
- Mold Removal & Black Mold Removal → Removing visible mold, including dark-colored growth people call black mold, from walls, ceilings, framing, and contents.
- Mold Inspection & Testing → Visual inspection, moisture mapping, and air or surface sampling to find hidden mold and its water source.
- Mold Clearance Testing → Independent post-remediation testing that confirms the job is done before walls close up or tenants move back in.
- Crawl Space Mold Remediation → Mold on joists, subfloor, and sill plates under raised-floor homes, plus the drainage and vapor fixes that keep it from returning.
- Attic Mold Remediation → Mold on roof sheathing and rafters from leaks, bath fans venting into the attic, and poor ventilation.
- Mold After Water Damage or Flooding → Drying, tear-out, and mold remediation after leaks, burst pipes, and Russian River and creek flooding.
- Bathroom Mold Removal → Mold in shower walls, behind tile, under floors, and on ceilings from leaks and bathrooms without working fans.
- Wall & Drywall Mold Removal → Cutting out and replacing moldy drywall and insulation, and finding the leak or condensation behind it.
- Musty Smell & Hidden Mold Investigation → Tracking down the source of a musty odor when no mold is visible, from wall cavities to crawl spaces and ducts.
- HVAC & Duct Mold → Mold in furnace cabinets, air handlers, and ductwork, coordinated with an HVAC contractor where equipment work is needed.
- Plumbing Leak & Under-Sink Mold → Mold from slow leaks under sinks, behind dishwashers and toilets, and around water heaters and washing machines.
- Rental Mold Inspection & Remediation → Mold in rentals for landlords and tenants: visible mold as a substandard condition under state law, code enforcement, and documentation.
- Home Sale Mold Inspection → Mold inspections during escrow, since termite reports exclude mold, plus remediation before listing or closing.
- Commercial Mold Remediation → Mold remediation for offices, retail, multi-unit buildings, and property managers, scheduled around tenants and operations.
- Mold Air Quality Testing → Air sampling and ERMI-style dust testing, what the lab report can and cannot tell you, and when testing is worth paying for.
Frequently asked questions
When did San Anselmo last have a major flood?
The most recent major downtown flood was on December 31, 2005, when San Anselmo Creek overflowed and more than four feet of water ran down San Anselmo Avenue. Earlier floods include January 1982 and several before that, back to at least 1925, according to the San Anselmo Historical Museum.
My crawl space flooded. Can it just dry out on its own?
Sometimes, but it is risky. Floodwater carries contaminants, and wet insulation and stored items under the house hold water for a long time. The EPA advises drying within 24 to 48 hours. If that did not happen, or you can see growth or smell mustiness, have the crawl space assessed.
Is mold remediation different for an older San Anselmo home?
The process is the same, but older homes add steps. Homes built before 1980 may need asbestos testing before drywall, flooring, or ceiling material is removed, and raised-floor homes usually need the crawl space moisture addressed as part of the fix.
Should the company that removed the mold also test it afterward?
California law does not prohibit it, but we recommend an independent firm for clearance testing so the result comes from someone with no stake in the cleanup.
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