An owner opens the crawl-space hatch after a wet week and finds standing water. Another notices a damp strip of carpet along an exterior wall, or a white crust on the garage slab. The instinct is to fix what is visible. The better first question is how the water arrived, because the answer decides whether the fix is a downspout extension or something more involved.
There are five common paths in Del Mar homes. Most houses have one dominant path. Some have two.
The ground beside the wall
The simplest path is surface water that collects against the foundation and soaks downward. The residential code expects the opposite. Lots are to be graded so water drains away from foundation walls, with the ground falling at least six inches within the first ten feet. Where a property line, wall or slope prevents that, swales or drains are to carry water away instead. Hard surfaces within ten feet of the foundation are to slope at least two percent away from the building.
Over the decades, many homes lose that fall. Planting beds get built up with mulch and soil. A patio settles toward the house. A neighbor’s new wall blocks the original swale. Each change returns water to the foundation. Our foundation drainage page describes how the grade is checked and corrected.
When the crawl space sits lowest
Raised cottages raise a particular question. The code generally allows the ground inside a crawl space to sit at the bottom of the footings, which is often lower than the yard outside. That arrangement has a limit. Where groundwater can rise to within six inches of the finished floor at the building perimeter, or where surface water doesn’t readily drain from the building site, the under-floor grade is to be as high as the outside finished grade, unless an approved drainage system is provided.
In practice, a crawl space that sits below the surrounding yard becomes a basin when the yard is saturated. Water seeps through or under the stem wall and pools. Older Del Mar cottages were often built before anyone checked this relationship. Our raised foundation repair page covers the remedies, which range from regrading outside to drainage inside the crawl space.
Slab edges, sills and the base of stucco
Slab-on-grade homes have their own path. Where exterior grade or paving sits too close to the top of the slab, water can reach the joint between the slab and the wall framing. Wind-driven rain off the ocean can push water against that joint as well. The base of stucco walls, where the finish is meant to end above grade and let moisture drain out, gets buried by later landscaping more often than owners realize.
The usual symptoms are dampness at the bottom of interior walls, deteriorating baseboards, or efflorescence on the garage slab near an exterior wall. The cure begins outside, by restoring clearance between the soil and the wall.
Groundwater, rather than rain
Some Del Mar ground holds water close to the surface for reasons unrelated to the last storm. The City’s hazard mitigation annex notes that the whole city lies within the Coastal Zone and that its local coastal program requires disclosure of the Floodplain Overlay and Coastal Bluff Overlay zones. Low-lying areas near the river valley and the beach behave differently from hillside lots, and their water table can rise with wet seasons and high tides.
A crawl space that stays damp through dry weeks, or pools without any rain, points toward groundwater. That path calls for a different approach than surface drainage, and it is one reason the code ties under-floor grade to groundwater height. Our North Beach floodplain foundations page addresses low-lying homes specifically.
Water from inside the walls
Not every intrusion comes from outdoors. A supply line leaking under a slab, a failed shower pan, a water heater drain or a condensate line can all put water beneath a home. The pattern differs: the dampness doesn’t track the weather, and it may sit in the middle of the house rather than along an outside wall. Our entry on under-slab leaks explains how to rule the plumbing in or out with the water meter.
Tracing a path, patiently
Telling these paths apart is mostly observation over time:
- Note the timing. Does the water appear during rain, a day after, or regardless of weather?
- Note the location. Along one wall, at the low corner, in the middle of the floor?
- Note the neighbors. Is the house next door dealing with the same thing?
- Walk the outside in the rain. Watch where roof water lands and where it goes.
- Read the meter with the house at rest, to exclude plumbing.
- Photograph and date each observation, including dry-weather conditions.
For second-home owners, a caretaker’s dated photographs after significant storms give a professional far more to work with than a single visit.
The map and the paperwork
Del Mar participates in FEMA’s National Flood Insurance Program, and the City notes that the current Flood Insurance Rate Map became effective on December 21, 2019. Owners in mapped areas should know the zone their property falls in, both for insurance and because certain repairs below the floor are subject to flood-resistance rules. The code ties construction in flood hazard areas to separate requirements, which our flood vents entry touches on. We don’t predict how any agency will view a given project; the City’s building staff is the authority on what applies.
Where the collected water goes
Once water is gathered by a drain or a sump, it must go somewhere. The City’s stormwater chapter names irrigation practices, power washing and minor home maintenance among the residential activities expected to follow best management practices. Before routing pumped water or a new drain toward the street, confirm what the City allows. Discharging onto a neighbor’s lot or onto a slope creates new problems of its own.
Elements of the scope
Which path is active, how long water has been present, the condition of wood framing or slab edges it has reached, crawl-space access and height, whether drainage work outside or inside is needed, and any flood-zone requirements all influence the scope of a repair. When moisture has affected structural members, we coordinate with licensed engineers as needed.
We serve all of Del Mar, from the beach and the river valley to the hills. If water is reaching the underside of your home and the source isn’t obvious, request a Free Quote.