A Safety Guide for Bay Area Residents

Mudslides

Mudslides can be hazardous for any home in the Bay Area. Photo: Engineered Soil Repairs, Inc. ©2019

Landslides or mudslides are a yearly threat to residents of the Bay Area. The region’s sudden, strong rainstorms and steep slopes can combine to make the perfect mudslide conditions. Because these events occur with little warning, it’s important to learn how to keep your loved ones safe. There are also steps homeowners can take to minimize potential damage.

 

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Take precautions now if you think your property is at risk for landslides or mudslides. Photo: Creative Commons ©2019

If You Think Your Property is at Risk for a Mudslide...

Take these steps:

  1. Learn about the history of your property. Areas that have experienced landslides in the past are likely to experience them again. Your city may keep records of past landslides, and you can also try this landslide inventory-mapping tool (in beta) from the California Department of Conservation.
  2. Hire a professional to evaluate the drainage on your property. You may need to build channels to deflect flow around buildings. Be aware: you are responsible for damage to neighboring properties caused by water diverted from your own.

Read all five steps for protecting your property from a mudslide.

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What You Need to Know About Mudslides

  • The Causes of Mudslides

    Slope Stability

    Ninety-nine percent of the time, mudslides are caused by water affecting the stability of a slope. There are two basic forces that determine slope stability.

  • Understanding Bay Area Landslide Risk

    Landslides in the Bay Area

    Geophysicist Dr. Ross Stein discusses how Bay Area homeowners can better understand and mediate their risk for landslides.

  • Infographic: How to Stay Safe in a Mudslide

    Infographic

    If you're worried about a possible mudslide, keep these emergency procedures in mind.

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Research

Tips About Mudslides, Soil Erosion, Drainage & More From Diamond Certified Experts

Jim Gardner

Jim Gardner Construction Inc.

George Walton

Alameda Structural, Inc.

Mark Corrallo

All Seasons Construction

Michal Gerard

Michal Gerard Construction

Christopher Wells

Christopher Wells Construction, Inc.

Jeremy Ke

All Seasons Construction

Vic Cvijanovic

Pacific Landscaping

Solutions for Drainage Problems

Solutions for Drainage Problems

OAKLAND — When it comes to drainage, most homeowners don’t realize there are two different types of water that need to be addressed: surface water and subterranean water (also known as groundwater). Furthermore, these two types of water each require specific solutions to prevent subsequent problems.

Surface water solutions

For most properties, the primary source of surface water is rainwater that comes off the roof. While all homes have some form of gutter and downspout system, the downspouts on some older homes don’t properly divert water away from the structure; they just drain directly onto the ground. When this is the case, the water goes directly into the soil next to the home’s foundation, which can lead to foundation erosion and settlement over time.

To prevent this, make sure all of your downspouts are connected to piping that diverts rainwater away from your home’s structure. Ideally, all of your downspouts should terminate at least five feet away from your home. Another option is to install permanent underground drainage lines that carry rainwater to your yard or the street.

Groundwater solutions

Groundwater is water that gets beneath your foundation and, if not addressed, can seep up into your crawl space and basement. A good solution for groundwater issues is what’s called a French drain—a gravel-filled trench with piping that redirects water away from the area. To be effective, French drains need to be dug below the lowest point of wherever your drainage problems are occurring.

By addressing both surface water and groundwater, you can develop a comprehensive drainage system that protects your home exterior and foundation from related problems.

The Importance of a Pre-Purchase Soils Report

The Importance of a Pre-Purchase Soils Report

ALAMEDA — When buying a home in the Berkeley Hills, one important step is having a soils report performed by a geotechnical engineer. Why? Because if the home needs foundation work, you’ll need to know what type of soil it’s sitting on.

I’ve seen many instances in this area where foundation repairs were improperly engineered because no one had performed a soils report. This can lead to dire consequences—in fact, a foundation repair that’s incorrectly performed can result in a worse situation than what the home was previously in. For example, drilling a pier in the side of a hill that’s composed of landslide material can encourage a landslide to occur. Likewise, drilling a pier in the wrong kind of soil material can drag the house down rather than stabilize it. Either of these situations (and the expensive repairs that go along with them) can be easily avoided by simply getting a soils report beforehand.

A Crucial Component of Earthquake Safety

A Crucial Component of Earthquake Safety

OAKLAND — Due to concerns about earthquake safety, many Bay Area homeowners are taking preemptive action by having their homes retrofitted via measures like foundation bolting and bracing. While retrofitting is a great idea, there’s one caveat: if your home’s foundation is poor or weak, bracing and bolting won’t do much good. For example, when an earthquake strikes, a bolt that’s anchored in weak concrete could easily snap out of the side of the stem wall, which eliminates any of its intended benefits.

The best way to avoid wasting your money on pointless retrofitting measures is to hire a quality retrofitting company—preferably one that also handles foundation work. A company that doesn’t do foundation work may not be able to provide all the services you need or even inform you about them, but a well-regarded retrofitting company will give you the straight scoop and provide everything you’re looking for.

The Importance of Controlling Groundwater

The Importance of Controlling Groundwater

SOQUEL — One of the most overlooked sources of potential damage to a home is inadequate soil drainage. When water is allowed to collect around the perimeter of a home, it can lead to numerous problems, including foundation settlement, termite infestation and the growth of harmful fungi like dry rot. As a homeowner, the most important thing you can do to protect your investment is control the groundwater outside of your house.

There are a few proactive steps you can take to control exterior groundwater. One is to avoid situating plants right next to your home’s foundation or attaching planter boxes to your home’s exterior. Even more important is to make sure the ground outside your home is properly graded, which will cause water to run away from the foundation rather than collect around it. Taking these and similar measures to control groundwater will help you safeguard the structural integrity of your home and avoid costly repairs.

Assessing Your Home’s Foundation

Assessing Your Home’s Foundation

BRISBANE — Earthquakes are an ongoing concern for anyone who lives in the Bay Area. One way you can be proactive about protecting your home and family is to know the condition of your home’s foundation. If you understand the signs to look for, you can determine if measures are needed to bolster your home against earthquake damage.

Depending on when your home was built, the character (as well as the quality) of its foundation can vary. For example, many houses built in the 1920s and ’30s have foundations that were engineered using local materials, which isn’t good. Local sand contains impurities, which leads to degradation of the concrete. Also, builders in those days likely didn’t use enough Portland cement, as it was very expensive.

To assess the condition of your home’s foundation, perform this simple test: go down to your basement with a hammer or screwdriver and attempt to scrape off a piece of your foundation. If you’re successful, it’s a sign that the foundation’s integrity is compromised, in which case you should call a structural engineer.

Another thing to look for when assessing your home’s earthquake readiness is signs of foundation settlement, which can be caused by anything from poor soil compaction to drainage issues. In most cases, signs of foundation settlement can be found inside the home in the form of wall cracks, whether in corners or diagonally above doors and windows. Another common sign is a door or window that suddenly becomes difficult to open or close. If you start to notice these signs in your home, it might be time to get a professional assessment from a structural engineer.

Identifying Groundwater Issues on Your Property

Identifying Groundwater Issues on Your Property

OAKLAND — Groundwater issues are a major concern in the Oakland/Berkeley area. Following heavy rains, the water that saturates the hills starts to move downward, eventually making its way toward the bay. As it travels, this water encounters a lot of home foundations. On vulnerable properties, water may be able to penetrate the foundation and seep into the crawlspace. Over time, this recurrent water intrusion can result in major damage to these below-grade areas of the home.

To prevent these kinds of issues, you should inspect your foundation and crawlspace following heavy periods of rain and check for signs of water intrusion. Here are a few things to look for:

  • White efflorescence around the foundation or in the crawlspace
  • Cracks in the ground near the foundation or in the foundation itself
  • A musty odor emanating from beneath the home

These are all indicators that water is getting into your crawlspace through your foundation. If you notice one or more of these issues, have a drainage professional take a look at your home. Often, this kind of issue can be remedied by installing French drains on either side of the home, which will prevent water from getting into the crawlspace.

Winter Drainage Tips

Winter Drainage Tips

WALNUT CREEK — Due to the rainy weather, one of the biggest concerns during the winter is proper drainage. To prevent water and/or structural damage to your home, you should inspect two key areas before the season begins:

Gutters
The single most important measure you can take before winter is to make sure your gutters and downspouts are clean and functional. You should also check the drainage basins around your property (if there are any). A good way to test your downspouts and other drainage components is to insert a garden hose and make sure the water flows out as it should; if it doesn’t, there’s a clog somewhere.

Crawl space
Drainage is critical in the crawl space beneath your home, so you should check it periodically throughout the winter. In most houses, the crawl space can be accessed through an entrance located in a bedroom closet. Don’t worry, you don’t actually have to crawl underneath your house—simply take a flashlight and look around. If you see any standing water or smell a damp odor, consider it a red flag. Standing water beneath or around your house is not only bad for its structure; it can impact your personal health as well.

If you discover moisture in your crawl space during the winter, there isn’t a lot you can do because of the wet conditions. Once spring arrives, have a professional come out and address the problem so you’ll be well-prepared for the following winter.