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Earthquake Requirments

Thursday, December 29, 2011

What are the earthquake strap requirements for water heaters?

Unfortunately, divergent methods and opinions abound among those who install, inspect, or approve various kinds of strapping. At the root of the problem is a lack of adequate notification by the state agency responsible for the advent of current seismic standards.

Since 1982, the Uniform Plumbing Code has mandated seismic safety straps for most water heaters. The purpose of this requirement is to prevent fire, explosion, or water damage if a water heater should topple during an earthquake. Originally, the code merely stated that water heaters “shall be anchored or strapped to resist horizontal displacement due to earthquake motion.” But no installation standards were included with this code. Types of hardware and methods of attachment were left to the discretion of the installer.

In the 1990′s, strapping requirements were upgraded. According to the newer code, “Strapping shall be at points within the upper one-third and lower one-third” of the water heater. To date, this is all the plumbing code has to offer on the subject. Two straps are required, but there are still no specifications as to techniques and materials to be employed.

Unknown to many, however, is the fact that the plumbing code, as it relates to water heater strapping, has been superceded by higher standards set forth by the California Health and Safety Code. In 1989, Assembly Bill 1890 was passed by the state legislature, establishing the following health and safety standards: (1) All water heaters sold in California shall be braced. (2) Manufacturers of water heaters must provide installation instructions for seismic straps with each fixture sold; (3) The Office of the State Architect must prepare generic installation instructions with standard details illustrating minimum standards for earthquake strapping.

The State Architect’s specifications, published in 1992, stand as the legal criteria for adequate strapping of water heaters in California. Unfortunately, efficient communication is not the hallmark of common bureaucratic practice, and in keeping with this deficiency, individuals at the state level seemingly neglected to inform building departments, home inspectors, and plumbing contractors that new seismic standards had taken effect. Consequently, years have transpired since the inception of current state guidelines. Violations and misapplications remain commonplace, because professionals who should have been advised remain unaware that new statutes have been established.

• Basically, the effective standards are these:
• All water heaters must be strapped, whether gas or electric.
• Two straps are needed, one in the upper one-third and one in the lower one-third of the fixture.
• Straps may consist of either plumbers’ tape (at least 24 gauge) or half-inch diameter metal conduit.
• Straps should wrap all the way around the body of the water heater. (Note: Many of the strapping kits available in hardware stores fail to comply with this requirement.)
• Straps should be secured to adjacent walls and from opposing directions.
• Straps should be secured to the wall studs using 1/4″ diameter by 3″ long lag bolts with washers.

Dissemination of the foregoing protocols is essential and long overdue. To obtain an illustrated copy of these standards, contact the Building Standards Commission at (916) 445-1230. Ask for a copy of “Earthquake Bracing of Water Heaters for Residential Use.”