Strengthen Soft and Weak Story Construction

05/03/2023

Why does it matter?

It is essential to strengthen soft and weak-story homes with first-floor open areas or parking underneath, such as garage apartments. This type of condition is especially vulnerable to collapse in earthquakes because the strength of the bottom story is substantially less than the stories above it.

What do I need to know?

• Garages with living space above are among the most common examples of residential soft stories.
• Two-story homes can also exhibit soft-story weakness if the first floor has relatively large window and door openings with fewer supporting interior walls than the floors above.

• Soft story conditions can exist when perimeter cripple walls have no inside face sheathing and under-floor basement areas have few or no interior walls to provide interior support.
• Any story can become a soft story if earthquake loading exceeds the design strength of that story.

Where do I start?

• Consult a licensed engineer to determine the most effective way to upgrade and increase the strength and stiffness of your first story if you have a weak or soft story condition.

Where to explore and more:

FEMA 232, Homebuilders’ Guide to Earthquake-Resistant Design and Construction