Mold Remediation and Mold Testing in Kentfield

One of the wettest places in the Bay Area

Kentfield's long-term average rainfall is about 48 inches a year based on NOAA records, against roughly 32 inches in Santa Rosa. The record wettest month was February 1986, with nearly 27 inches, and the heaviest single day on record brought more than 11 inches on January 21, 1967.

That much rain is a mechanism, not a mold statistic. What it does is test every weak point in a house each winter: a roof flashing that lets water into the attic, a gutter that dumps against the foundation, a crawl space where groundwater seeps in, or a window frame that wicks water into the wall. Each of those can keep wood or drywall wet long enough for mold to grow. The EPA advises drying water-damaged materials within 24 to 48 hours to prevent it.

Kent Woodlands and the north slope of Mount Tam

Kent Woodlands, with about 565 homes, sits in a bowl on the north-facing slope of Mount Tamalpais. North-facing, tree-covered slopes get less direct sun, so roofs, decks, siding, and the soil around foundations dry more slowly after storms. Hillside homes also tend to have one side dug into the slope, where soil and runoff sit against the foundation wall all winter.

The places to check in those homes:

• Lower levels and crawl spaces on the uphill side, where walls can stay damp and finishes can hide growth.
• Attics under shaded roofs, especially where bathroom fans vent into the attic instead of outdoors, or where a leak around a skylight or chimney has gone unnoticed.
• Decks and balconies attached to the house, where water can get behind the ledger board and into the wall.

Corte Madera Creek and the valley floor

Corte Madera Creek runs through the flat part of Kentfield on its way to the bay. The December 31, 2005 storm caused roughly $90 to $100 million in damage across the Ross Valley, including Kentfield, according to Marin County's flood control district. The county's Corte Madera Creek Flood Risk Management Project, aimed at reducing flooding in Ross and Kentfield, includes a stormwater pump station for the Granton Park neighborhood that the district reported substantially complete in 2024. In February 2026 the district paused the remaining creek work for review, so check with the Marin County Flood Control District for the current status.

If a creek or storm flood puts water in a crawl space or lower floor, the materials it soaks usually have to be removed rather than dried, because floodwater is contaminated. See mold after water damage or flooding for how that cleanup works.

Housing age, rentals, and licensing

Census estimates put the median Kentfield home construction year at about 1956. Homes built before 1980 can contain asbestos in joint compound, textured ceilings, flooring, and duct wrap, so testing may be needed before a remediation crew removes those materials. Asbestos work requires a contractor with CSLB asbestos certification or a C-22 license plus DOSH registration.

Because Kentfield is unincorporated, apartment buildings with three or more units fall under Marin County Environmental Health Services, which inspects them about every two years and on complaint. It does not test for mold, and it does not cover single-family or condo rentals. Under Health and Safety Code section 17920.3, as amended by SB 655, visible mold can make a rental substandard. See rental mold inspection and remediation.

California has no mold license. Any job of $1,000 or more needs a CSLB-licensed contractor, commonly one with a B General Building or C-61/D-64 license. Check 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 (EPA mold guidance).