Marin County Hillside Drainage & Crawlspace Waterproofing

Why Marin properties have drainage problems

Much of Marin County is built on the Franciscan Complex, a jumbled mix of sandstone, shale, chert, and serpentinite. Weathered on the surface, these rocks become dense clay that swells when wet and lets water move sideways along hidden layers instead of soaking straight down. On a hillside lot, that sideways water ends up in your crawlspace, behind your retaining wall, or under your slab.

Add winter atmospheric-river storms that can drop several inches of rain in a day, and older homes built before modern drainage practices, and you get the classic Marin symptoms: a standing pond under the house in January, a weeping cut bank behind the garage, a leaning wall, or a driveway that turns into a creek.

How it works

Tell us what you are seeing with the form or a quick call. We pass the details to a licensed local drainage contractor, who follows up to schedule a site visit to trace where water enters the property, how it moves through the soil, and where it can legally be discharged.

The contractor explains the cause and gives you a written scope, whether that is a sump pump, a curtain drain uphill of the house, a French drain system, or wall drainage. There is no obligation to proceed.

Drainage systems we help Marin homeowners with

Crawlspace and sub-slab sump pumps with battery backup. Curtain drains and interceptor trenches that catch hillside seepage before it reaches the foundation. French drains and downspout tightlines that carry roof and surface water to an approved outlet. Retaining wall drainage, including weep holes, drain rock, filter fabric, and perforated pipe behind failing walls.