Much of live/work is built as renovation of older industrial and commercial buildings which were built long before current, if any lateral building standards were part of building codes. A "lateral load" is a sideways force on a building such as wind or an earthquake. Seismic retrofits to current code can be very expensive, and this cost can be the most important factor inhibiting conversion of some existing buildings to live/work use. This fact at times conflicts with the stated desire of cities to see underutilized (often vacant) buildings converted to a use for which there is often a pressing need and market demand.

Certain buildings have been shown through such experience to be extremely unsafe in earthquakes. The most notable are Unreinforced Masonry Buildings (URM’s or, in San Francisco, UMB’s). The state of California -- and no doubt others -- have passed strict laws regarding mandatory upgrade of the buildings, laws which would supercede any other code relaxations for live/work.

Normally when a building is changed from commercial to residential occupancy, this triggers a change of use -- treated in detail elsewhere -- requiring it to conform to today’s code, including lateral loading. Some cities have said that it is, but has made specific exceptions to the lateral requirements in live/work conversions, requiring retrofit only to 75% of current code rather than a full seismic upgrade.