Earthquake retrofit components fall into two primary categories: metal connectors and wood bracing panels. The steel anchor bolt, which is the original seismic component, was used in a few homes in the 1920s and 1930s, and became a standard requirement in the 1940s. Anchor bolts are designed to prevent horizontal movement and are intended to keep the house from sliding off the foundation.

Modern construction standards call for bolting at least every six feet, with bolts within the last 12 inches of each piece of sill plate. Buildings with more than one story, or on hillsides, may need anchor bolts every four feet. Anchor bolts can be added to existing foundations if the concrete is strong enough to hold them. Many older foundations have poor quality concrete, which will break apart when bolts are installed or when stressed by an earthquake. Wedge type anchor bolts were the standard retrofit device for many years. Wedge anchors expand against the concrete and may loosen with time and periodic vibration. Most engineers now prefer bolts set into epoxy. Epoxy bolts do not place a strain on the concrete until the actual seismic event and are especially useful if the concrete does not have full strength. Epoxy-set bolts have even been used in some brick foundations.

New foundations may also have L-shaped brackets called "hold downs," which are bolted down into the foundation and horizontally to the vertical framing. Hold-downs are designed to prevent vertical upward movement and are especially effective if secured to the framing at plywood bracing panels or "shear panels." The weakest part of the building is usually the short, or "cripple," walls that support the lower floor framing. Most older buildings rely on diagonal blocking or let-in braces to keep these walls vertical. Blocks and braces are no longer considered adequate and the new standard calls for plywood bracing panels, often referred to as "shear panels." Properly installed bracing panels can significantly reduce the potential for structural failure. These panels make the building stiffer, and may actually cause more interior damage, such as plaster cracking and falling furniture, in a well-braced house during a minor or moderate earthquake.

Life safety is not considered by some experts to be a primary concern because serious injury or death in single-family, wood-framed residential structures is very rare during an earthquake. The primary purpose of seismic reinforcement is to keep the house from becoming a total loss when the big quake comes.

The plywood or OSB (Oriented Strand Board) bracing panels should be properly nailed and supported by framing on all four edges. The nails should be no more than six inches apart and ideally no more than three inches apart. The nails should not be over-driven, which would weaken the connection. Screws should not be used, as they may break off under stress. Metal straps are now available to reinforce the connection between the bracing panels and the floor framing above. These are easy to install and can substantially increase the strength of the system.