Bracing the cripple wall to prevent collapse during seismic movement is a very important part of earthquake retrofitting.

The bracing or stiffening is accomplished by attaching structural grade plywood tightly to the wall framing. In engineering language, this strong or stiffened wall is referred to as a shear wall.

Load transfer is an engineering term which in everyday language means that the effects of the earthquake movements are transferred from one of the buildings components into the next - ground to foundation, foundation to sill, sill to wall, wall to floor. Good detailing of all of these connections is an important part of retrofitting technique.

Cripple wall bracing

"I have a what?" Not many property owners really know their home's construction in this kind of terminology. But cripple wall collapse is the main reason for earthquake related failure.

Most houses have a short wood-framed wall in the sub-area crawl space. The wall ranges from a few inches to several feet high, running upward from the top of the concrete foundation to the bottom of the main floor. In some cases, the collapse of the cripple wall could result in the main floor dropping to the ground. We've all seen those devastating pictures after an earthquake. In most cases, the house is a total loss.

So, it's very important to brace the cripple wall to keep it from collapsing during seismic movement. This is typically done by attaching structural grade plywood tightly to the wall framing. The materials and hardware used are specified by the Uniform Code of Building Conservation and the Los Angeles Building Code. This is not a do-it-yourself project.

Foundations of older houses and buildings need to be retrofitted since many construction techniques used years ago are not earthquake safe. Your home is an investment and, of course, your family's shelter. Be sure it's ready for the next big shake. We will provide you with an estimate and can get the work done right away.

Following the principle that a chain is only as strong as its weakest link, it is also important to complete the connection from the foundations, through the walls, and into the overhead floor framing. This will provide for good load transfer.