Single Family Homes

Most single family homes in the Bay Area will resemble one of six common housing types. Can you identify yours?

IDENTIFYING FEATURES

Many homes have clues to help you ID them from the street. In all cases additional steps are needed, but this provides a rapid way to spot home types.

Common Problems in an Earthquake

In past earthquakes engineers have spotted common damage patterns. This section will describe common problems before you take the Quiz and get more information.

COMMONLY FOUND WITH

Many Bay Area homes don’t fit nicely into a single category. If your home fist more than one type, take the quiz for both.

NEXT STEPS

Spoiler Alert! The next step is always to take the quiz. Use this website to help you accurately ID your home type. The Quiz will provide steps a building owner can take to confirm or address vulnerabilities.

Single Family Homes

Bay Area single family homes come in a variety of types and styles. Many neighborhoods were built around the same time, so the houses have similar materials and designs. The overwhelming majority of single family homes are wood frame construction. In small quakes, wood frame houses tend to do well, because wood can bend and twist a little without breaking. However, in stronger shaking, the damage may be severe and is described for each home type below. Many identifying features are relatively distinctive and will make identification easy, while others may be more difficult. Additionally, your home may be a blend of multiple types. If your home has characteristics of more than one type, explore the sections for each type. Use this website to identify what possible problems your home may have, and take the Quiz for more detailed information about potential problems and a list of things you can do to avoid damage and make your property safer.

Home with a Crawl Space

Also Called:  CRIPPLE WALL

One of the most common types of single family homes in the Bay area is wood frame with a crawl space. The term crawl space refers to unoccupied space between the foundation and the first floor, which is usually only a few feet tall, and is framed by a “cripple wall.” Most single family homes on flat sites built before 1940 have a crawl space, as well as both older and newer homes built on slight slopes.

Identifying features: 

  1. The first floor is not level with the ground.
  2. There are typically multiple steps up to the doors.
  3. There are typically vents/screens along the perimeter of the house between the foundation and the first floor.
  4. There is often a larger opening that allows for someone to access the crawl space.

Commonly found with: 

It is common for this housing type to also have other vulnerabilities. It is common for homes with a crawl space to also have a living space over garage, be built into steep hillside, or have a split level feature. Check the Living Space Over Garage Home, Home Built Into a Steep Hillside or Split Level Home sections to determine if your home has any of these vulnerability too.

Common Problems in an Earthquake: 

If the cripple wall frame is not bolted to the foundation, the home may slide off the foundation. If the cripple walls are not strong enough, some or all of the crawl space can collapse under the weight of the home above. If either of these occur, the home can sustain considerable damage, and may be uninhabitable. In addition, the home’s gas, water or sewer lines may also break. The cost to repair, or demolish and rebuild, can be very high.

Next Steps: 

Identifying your home’s type is just the start. Find out more important information about your home in the Earthquake Home Safety Quiz.

Home with a Slab Foundation

Also Called:  SLAB ON GRADE

Many homes built after the 1940s on flat sites are built with a slab foundation. A slab foundation is made of a solid slab of concrete and extends to all sides of the home. The home typically sits directly on top of the slab.

Identifying features: 

  1. The first floor is level or near-level with the ground.
  2. There is typically zero to one step to the front door.
  3. There are typically not vents present, however, there may be a single appliance vent near the ground on the first floor.

Commonly found with: 

It is common for this housing type to also have other vulnerabilities. It is common for homes with a slab foundation to also have Living Space Over Garage Homes. Check the Living Space Over Garage Homes section to determine if your home has this vulnerability too.

 

Common Problems in an Earthquake: 

In an earthquake, structures with this foundation type generally perform well. In some cases, pre-1960 homes on a slab foundation may not be sufficiently anchored to the foundation and can shift in an earthquake. Some walls of the home may lean and crack in an earthquake if this happens.

Next Steps: 

Identifying your home’s type is just the start. Find out more important information about your home in the Earthquake Home Safety Quiz.

Living Space over Garage Homes

Also Called:  HOUSE OR ROOM OVER A GARAGE

There are two versions of homes with living space above a garage: (1) House Over Garage, where the first story of the home primarily consists of a garage and unfinished space (i.e. not livable space) and the majority of the living space is above this, and (2) Room Over Garage, where only a portion of the house is above the garage and the rest of the house has a different foundation type (i.e. crawl space or slab foundation). 

Identifying features: 

  1. The garage is integrated into the structure of the house, with living space above.
  2. House Over Garage, all living space is on the second floor above the garage.
  3. Room Over Garage, some living space is on the first floor, some is above a garage.

Commonly found with: 

It is common for this housing type to also have other vulnerabilities. It is common for homes with a living space above garage to also have a crawl space or split level feature. Check the Home with a Crawl Space or Split Level Home sections to determine if your home has either of these vulnerability too.

Common Problems in an Earthquake: 

In an earthquake, the garage or unfinished space on the first floor may not be strong enough to resist the side-to-side shaking of an earthquake, leading to collapse of the garage area, or causing a permanent lean. If the garage collapses, the second floor area above it is also likely to be a greater risk for serious harm to occupants in this portion of the home. The home can become uninhabitable if the garage wing or first story leans significantly or collapses.

 

Next Steps: 

Identifying your home’s type is just the start. Find out more important information about your home in the Earthquake Home Safety Quiz.

Home Built Above a Steep Hillside

Also Called:  DOWN-SLOPE HILLSIDE HOME

Homes built above a steep hillside have increased potential for earthquake damage. In these homes, the main living level is built at or near street level, with piers or posts embedded in the ground that support the rear of the house. Homes built into steep hillsides are discussed below

Identifying features: 

  1. If slope drops one or more feet for every five horizontal feet on the perimeter of the building it is a “steep” hillside.
  2. The home extends out over the hillside with living or unfinished space below, either supported by tall stilts (may be braced, see image), or tall walls.

Common Problems in an Earthquake: 

In an earthquake, the home can shift, collapse downhill or tilt sideways on the hill. The anchorage connection to the uphill footing is a common weak point and the bracing or tall walls are also often not strong or stiff enough to resist the shaking. If the building collapses, residents can be injured or killed.

Next Steps: 

Identifying your home’s type is just the start. Find out more important information about your home in the Earthquake Home Safety Quiz.

Home Built Into a Steep Hillside

Also Called:  UP-SLOPE HILLSIDE HOME

These homes typically perform better than their Home Built Above a Steep Hillside counterparts (described on the previous page), but often have at least one of three other potential problems: crawl space, living space over garage and/or split level. 

Identifying features: 

  1. If slope drops one or more feet for every five horizontal feet on the perimeter of the building it is a “steep” hillside.
  2. Portions of rooms in the home are built into the hillside. The home was built into excavations cut in the slope.

Commonly found with: 

It is common for this housing type to also have other vulnerabilities. It is common for homes built into a steep hillside to also have a crawl space, living space over garage, or split level feature. Check the Home with a Crawl Space, Living Space Over Garage Home, or Split Level Home sections to determine if your home has any of these vulnerability too.

Common Problems in an Earthquake: 

In an earthquake, damage is typically related to the other problems: crawl space, living space over garage or split level. If your home has any of these problems visit these sections for common issues in an earthquake.

Next Steps: 

Identifying your home’s type is just the start. Find out more important information about your home in the Earthquake Home Safety Quiz.

Split Level Home

Split level homes come in a variety of shapes and sizes. The split level can be an architectural feature or be a result of sloping ground, or a garage with a living space above. Sometimes a split level home can be identified from the outside, but often verifying features are needed on the inside – mainly steps between rooms that don’t go up or down a full story.

Identifying features: 

  1. Floors that are at different levels, but less than one full story difference.
  2. Roof lines that are at different levels, but less than one full story difference.

Commonly found with: 

It is common for this housing type to also have other vulnerabilities. It is common for split level homes to also have a crawl space, living space over garage, or be built into a hillside. Check the Home with a Crawl Space, Living Space Over Garage Home, or Home Built into a Hillside sections to determine if your home has any of these vulnerability too.

Common Problems in an Earthquake: 

In an earthquake, the home may respond as two separate sections, one on each side of the shared wall. Separation between the sections can occur at the shared wall, with the possibility of severe damage or partial collapse. If the split level home also has a living space over garage or a crawl space, these elements can also fail as described in other sections.

Next Steps: 

Identifying your home’s type is just the start. Find out more important information about your home in the Earthquake Home Safety Quiz.

Learn more about your house, apartment or home

Identifying your home is just the start, there is more important information about your home in the Earthquake Home Safety Quiz.