The older hillside streets of Del Mar have a particular quality in the early morning. The light comes over the ridge, the eucalyptus drip after a marine-layer night, and the houses sit at odd angles to one another, each one fitted to its own piece of slope. Many were built before anyone in town was thinking about grading permits or soils reports.
Census Bureau estimates put about 243 of Del Mar’s roughly 2,550 housing units in the “built 1939 or earlier” category, with several hundred more from the 1940s and 1950s. A good share of the oldest houses are on these hillsides. If you own one, the foundation under it is likely older, simpler and more altered than the house’s finished rooms suggest.
What early hillside builders worked with
Early houses on a slope were usually fitted to the ground rather than the ground being reshaped for them. A short perimeter footing might follow the hill in steps. The downhill side might rest on taller walls, or on posts and piers. Concrete of that era was often lightly reinforced or not reinforced at all, and some piers were brick or stone.
Around the house, owners built terraces to make the hillside usable: low walls of stone, brick or concrete, often without drainage behind them. Decades later, those terraces are part of the slope’s structure, whether anyone designed them that way or not.
Generations of remodeling
Few of these houses are as they were built. A kitchen was enlarged in one decade, a bedroom added over the garage in another, a deck extended toward the view in a third. Each addition may sit on a different foundation, built to the standards of its time.
The result is a foundation that reads like a patchwork. Older and newer sections meet at seams, and those seams are often where movement first appears: a crack at the junction of two rooflines, a step in the floor at a doorway, or a gap where a newer deck meets an older wall.
When you’re reading the house, it helps to know roughly which parts were added when. Old permit records, where they exist, can help. So can changes in materials visible in the crawl space.
The slope and the ground beneath
The City’s hazard annex rates landslide and expansive soils as medium hazards for Del Mar. That doesn’t describe any particular lot, but it frames the concern. On older hillside lots, the questions tend to be about slow movement over long periods: soil creep on the downhill side, old fill behind terrace walls, and water moving through the slope after winter storms.
Signs that the slope itself may be involved include terrace walls that lean outward or show cracks that widen downward, downhill footings with fresh cracking, fence posts and steps that tilt downslope, and soil collecting against the uphill side of walls.
Seismic weaknesses in older construction
The California Existing Building Code’s seismic retrofit guidelines describe structural weaknesses common in older wood-framed houses: sill plates not anchored to the foundation, unbraced cripple walls, and inadequate connections between floor and foundation. On a hillside, these weaknesses can matter more, because the downhill cripple walls are often taller.
Strengthening these connections is often one of the more cost-effective improvements an older hillside house can receive, and it usually happens out of sight beneath the floor. Anyone proposing the work should coordinate with licensed engineers as needed.
Seasons on an older hillside lot
These houses tend to show their age on a seasonal rhythm. After a wet winter, doors on the downhill side may bind and terrace walls may weep at their base. Through a dry late summer, clay soils shrink, and hairline cracks at old seams open slightly before closing again with the next rain. That kind of back-and-forth is common in older houses and doesn’t always mean ongoing settlement.
What deserves attention is change that keeps going in one direction: a crack that is wider each spring than it was the spring before, a floor that continues to drop toward the hill, or a terrace wall that leans a little further each year. Simple dated photographs, taken from the same spot each season, make that pattern far easier to see.
Rules that may apply to repairs
Two sets of rules commonly come into play on these lots.
The first is the Bluff, Slope and Canyon Overlay Zone in Chapter 30.52 of the municipal code. Where it applies, it sets standards for development on steep slopes and near bluffs and canyons. Whether a given repair falls under it depends on the lot and the work.
The second is Design Review. The City’s resident handbook explains how the process works and what kinds of projects it covers. Many foundation repairs happen below the floor and don’t change the exterior. Others, such as rebuilding a visible retaining wall or raising a section of the house, may involve review. It’s worth asking early.
Neither set of rules lends itself to predictions about timing or outcome, so plan for review as a possible step.
A preservation-minded approach
Owners of these houses often want two things at once: a sound foundation and a house that still looks and feels like itself. Those goals aren’t in conflict. Most foundation work on older hillside houses can be done in ways that leave the visible character intact.
- Start with water. Many problems on older hillside lots slow down once roof water, irrigation and surface runoff are managed. It’s the least invasive step and often the most useful.
- Address connections next. Anchoring sills and bracing cripple walls adds strength without changing how the house looks.
- Repair rather than replace where possible. Individual piers, posts and sections of footing can often be replaced or reinforced without rebuilding the whole foundation.
- Treat terrace walls as structures. Old walls holding back soil near the house may need evaluation in their own right.
Gathering the history
Before an evaluation, collect what you can: any permits or drawings the City has on file, notes from prior owners, photographs from earlier years, and records of past repairs. Older houses often have gaps in the record. The evaluation will fill in what it can from the house itself.
What shapes the work
Effort depends on the age and type of the original foundation, how many additions sit on separate foundations, access to the crawl space and downhill side, the condition of terrace walls, drainage, and whether the overlay zone or Design Review applies. Those factors are worth understanding before any repair is chosen.
Our bluff and hillside homes page describes hillside foundation work more broadly, and the raised foundation repair page covers crawl-space repairs. We work throughout the City of Del Mar. When you’d like a considered look at an older hillside house, request a Free Quote.