Retrofitting homes can be a significant commitment of time, effort, and expense. Experts advise homeowners to consider carefully what they are getting into before taking on a do-it-yourself retrofitting project. Tools and equipment are expensive, even if renting. Licensed contractors can also be a significant expense. On the other hand, the investment in retrofitting versus the cost of major repair or reconstruction can pay off many times over.
Structural Integrity Potential Problem Areas
Foundations: Check for cracks, crumbling and evidence of standing water. Check the type of foundation and whether the structure is securely attached to it.
Cripple Walls: Cripple walls are the short walls between the foundation and the first floor. During an earthquake, cripple walls can act like hinges, allowing the house to shift off its foundation, which can rupture utility lines and damage the entire house. Reinforcement with plywood sheathing (called shear walling) is recommended as a preventive measure. Shear walling is also recommended at the ground floor for 2- and 3-story homes.
Garages: For homes with garages below the living spaces, steel reinforcement or added shear walling can help prevent structural buckling that is commonly caused by earthquakes.
Chimneys: More than 10,000 chimneys were destroyed during the Loma Prieta earthquake in 1989. Falling chimney bricks can cause injury or serious damage, including actually penetrating through the roof. The degree of vulnerability depends on the chimney's age, location, height and the condition of the mortar. Chimneys extending 5 feet or more above the roof are the highest risk. Consult a qualified contractor or engineer about your chimney's condition.
Masonry Veneer: Stone, brick and adobe are sometimes used around fireplaces or on the exterior of houses. Older veneers are especially vulnerable to earthquake damage, and not much can be done to reinforce them. Like falling brick, falling stone or masonry veneer can be extremely hazardous.