Artistic sketch of the terrain for a hillside homeHave you always dreamed of buying a hillside home, one close to, or in, the western foothills in Santa Clara County, such as Almaden, Los Gatos, Monte Sereno and Saratoga? Some of the prettiest parts of Silicon Valley are snuggled into the base of the Santa Cruz Mountains. With views of downtown San Jose and the southern San Francisco Bay Area on one side, and rolling, grassy and redwood & oak filled hills on the other, its certainly scenic. Additionally, these areas all tend to have lower crime and good schools.

Hillside homes may be subject to insurance difficulties if they are deemed to be in a high fire risk zone, and property owners need to plan for how to escape in case of emergency. Trees may fall and block ingress or egress, so many mountain residents carry chainsaws. There can be wildlife living nearby, munching on carefully installed landscaping, or threatening household pets or small children in some cases (mountain lions – never leave your children unattended in hillside areas!). In terms of the structure of the hillside home, or the home near the base of the foothills, water is perhaps the risk that is least appreciated but impacts many more homes than most people realize.

Hillside home and water challenges

As a savvy foothill-area buyer, you will want to understand some of the unique issues that this geography may present. The most important of these hillside issues may well be that of water control and drainage.

The Santa Clara Valley, and most of the neighboring Silicon Valley areas, is composed of mostly expansive clay soil. This is an extremely strong substance – so much so that settlers used it, mixed only with a little straw and water, to form adobe bricks for building.

The caveat with clay soil is that when it becomes wet, it expands, and when dry, it contracts. (Hence “expansive clay soil”.) The amazing thing is that the clay is more powerful than concrete. And that is the problem for houses and other buildings if the ground is expanding, contracting, or alternating between the two.


Foundation crack efflorescense


What can a homeowner do? Its imperative to try to control the amount of water near (or under) the home as much as possible.

For homes all over Silicon Valley, its important, my home inspector tells me, to use downspout extenders so that the water from rain collecting on the roof don’t all dump out right next to the house. Ideally the water would run to a swail, or to some other drainage system (likely leading to a gutter in the street). Additionally, it is important that soil (or walkways) be graded such that any water would run away from the house rather than toward it. Frequently, though, we see homes with ˜reverse grading and any rainwater, pool splashing etc. may run toward the house rather than away from it. Thats a problem that needs correcting.

Side note: Increasingly, municipalities want water to percolate back through the soil into the underground waterways, rather than to the gutter and off through the storm drains to creeks and the bay.

For homes near or in the foothills, things are further complicated because runoff from the hills may be aimed straight a neighborhood or home. Your hillside home may be in the path of the runoff, for that matter.

Geotech engineers (they are the specialists for this issue) will assist the homeowner (or buyer) in determining how to limit the amount of water moving toward the house. Sometimes that will be a combination of work with the downspouts, grading, and drainage systems. Other times its much more involved and costly. There are some areas in Los Gatos and Almaden Valley, for instance, where the water table is very high. During an El Nino year, with lots of rain, the water table may get pushed beyond the brink and a spring may pop up near or under your house. Capping the spring is not going to be a cheap fix. But be aware, if youre home buying in some of these areas, that you may run into this issue. If so, plan to call an expert, a Geotechnical Engineer, to assess the situation and provide suggestions to remedy it.

Hillside home and other water impacted area red flags

What are some of the symptoms, or red flags, to watch for if you’re buying a home near the hills, that there may be a drainage problem? Here’s a list of possible clues – they could also signal other issues too, so this is not a diagnosis, just a clue that something needs to be investigated:

  • floors out of level
  • interior doors that don’t close or stick
  • cabinet doors out of alignment
  • cracks in walls and at doors
  • cupped hardwood floors
  • musty smell in the house
  • cracked or lifted concrete outside, in the garage, or anywhere visible


Cupped Floors


Many homes in the foothill areas are sold with pre-sale inspections already done. Before writing an offer, review these carefully. The property or home inspection may also flag drainage issues that could be causing (or cause in the future) significant structural damage. Here are a few to look for:

  • cracks in the foundation
  • stains on the foundation or effusion (mineral deposits), indicating water in the crawl space
  • cracked, buckled, or lifted cement (which you may or may not have noticed)
  • mildew or mold in the attic (indicating a high amount of evaporation in or through the home)
  • reverse grading conditions

By carefully viewing hillside homes and reading the pre-sale inspection thoroughly, you should have a sense of whether or not there are any potential issues with water and drainage. You may also be surprised that the homeowner or seller has addressed these diligently. When the issue of drainage has been well handled, you may see these features at the property:

  • the concrete around the home and in the driveway is in good condition (and is not brand new – sometimes home sellers will replace the driveway or walkways but not address the cause, so sometimes a brand new bunch of paving is a red flag)
  • the grading appears correct
  • the downspouts are tied to an underground system that moves the water away from the house or has gravity’s help to move the water away from the structure (new homes may not permit the water to go to the gutter in some cases)
  • there are drains at points around the home to carry water away
  • you see no cracks in the garage floor (if you cannot see the floor due to rugs or storage, make sure you do see it!)
  • doors and windows all open easily
  • the crawl space is dry and appears to have a history of being dry

Finding a property in which the owner has aggressively addressed the issue of water around the house, particularly before there are any structural problems to fix, is a real boon to a home buyer. We live in a region where many sellers simply slap granite onto the kitchen counter and call the home improved or well maintained. The structural stuff isn’t very sexy, and most buyers don’t appreciate if drainage work is there or not, but ultimately it is one of the most important aspects of home buying to be evaluated. The right improvements and care will make the property more functional and in need of fewer repairs in the long haul, and will give savvy buyers peace of mine when they purchase it.


For further reading:

What about the living in the Los Gatos Mountains (Santa Cruz Mountains)? post on Move2SiliconValley relocation blog

Cracked Foundations, Adobe Clay Soils and Water in Silicon Valley (this blog)





  • Mary Pope-Handy

    Silicon Valley Realtor, selling homes in Los Gatos, Saratoga, San Jose, Silicon Valley, and nearby since 1993. Prolific blogger with a network of sites.

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