J.A.V. CONSTRUCTION.
Juan Adrian Velasco Construction.

Foundation bolting typically means that bolts are added to improve the connections between the wooden framing members of a building and its concrete foundation. Usually this means adding bolts through the piece of wood that lies flat on top of the foundation, referred to as the sill or mudsill, into the concrete. There may be no existing bolts, or the existing bolts may be either weakened or too far apart to be strong enough for earthquake resistance.

Careful planning, placement and installation of foundation bolts are critical for good bolting strength.
It is important to use the proper type of bolt corresponding to the existing conditions of the home and its foundation.
The expected type of bolt load or stress is another important consideration for bolt selection.

Two types of foundation bolts are typically used, referred to as expansion bolts and epoxy-set bolts.

Expansion foundation bolts cost less to install but require good concrete strength to work well. They are typically used in houses with newer foundations and in situations where the earthquake movement is expected to shear or "slice off" the bolt.

Epoxy-set foundation bolts work better in older and weaker concrete foundations and in situations in which the movement is expected to pull the bolt upward and out of its concrete anchor. The strength of epoxy-set bolts can also be improved by making them longer and setting them more deeply into the concrete.

The type, size and shape of the bolting washer also makes a difference in bolting strength. Current retrofitting standards call for thicker and larger square washers as compared to the small, thin, round washers found in houses built prior to the mid 1990s. This allows the sill to be clamped more securely to the foundation.