ABAG Shaken Awake! Report -
Wood-Frame Multifamily Buildings

1-3 Stories, Built Before 1940

Typical Building Damage

Similar earthquake safety issues apply to this category as to pre-1940 wood-frame buildings of 4 - 7 stories - poor foundation anchorage and reinforcing. In addition, it is not uncommon for pre-1940 apartment buildings to include chimneys. These are often unreinforced and lack proper ties to the structure. They may break off or fall inwards onto roofs or rafters causing further damage.


Most buildings in this category have lower onsite parking requirements relative to those of today. The first floor is therefore generally used as living space, half a level above grade to establish a degree of separation between the street and private areas within the building. Typically framed with wood posts, wood joists and stud walls, the exterior walls are usually reinforced with 1x diagonal sheathing boards. A less common form of construction was a first floor of unreinforced masonry, either housing additional units, or a lobby. Finally, this floor may have been built as, or converted to, parking. Such buildings exhibit typical "soft-story" problems.

Occurrence of This Building Type in the San Francisco Bay Area

The older more established regions of the Bay Area include the highest percentage of units of this building type. In San Francisco County, units in this type of building represent 25.9% of the total housing stock, and 39.2% of the multifamily stock. Units in buildings under 3 stories built prior to 1940 seem to be the most common form of shelter in San Francisco County for they account for the highest percentage of all building types. In Alameda County, they represent 9.5% of the total housing stock, and 24.9% of the multifamily stock.

ABAG, the Association of Bay Area Governments, is the regional planning and services agency for the nine-county San Francisco Bay Area.

This page is based on a 1996 ABAG report. It was last updated 9/26/03 by jbp.