Thread: Anchor Bolts -When first required

Hey all this may be a stupid question. But when did foundation anchor bolt become required?

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Originally Posted by Don Hester

Hey all this may be a stupid question. But when did foundation anchor bolt become required?

Don't have the exact date, but sometime after 1989 (Hugo) in NC.

Seismic details I believe preceed hurricane Hugo.

Don Hester,

Yep, I remembered correctly. I noted your profile location as being in Washiington state. I did not look up the local city references, or look up on a map just where in Washington state you are (don't recognize the reference off the top of my head).

Admit, I'm starting off with an assumption set, that you are questioning regarding site-built construction. I'm further assuming residential one-two family, not pre-manufactured, manufactured, or coach/mobile homes, and not federal lands, or tribal land construction in Washington state.

What I did do was refer to an older document produced in 1999 (took me forever to find it hosted somewhere on the internet), which relates the history of the UBC adoption in Washington state, and the changes in the Seismic Zone Map(s) in the UBC that effected the State of Washington, and some of the changes pertaining to the construction details for those zones, specifically your anchor bolt to foundation question.

I excerpt below, part of that document, which addresses the question of the original poster (see the clickable link following the excerpt to review tables, etc.), one would have to distinguish the actual local code adoptions and requirements if this is a residence built post 1956 and pre 1975 as to local code adoptions and/or ammendments - also depending if Puget Sound or the rest of the state.

Here is the promised excerpt *remember it was published October 1999* and is specific to Washington state and its history:

Building Codes and Practices Requirements

The Uniform Building Code (UBC) is the model building code adopted by most of the western half of the United States. The UBC was first introduced in 1927 by a non-profit, independent organication called the International Council of Building Officials (ICBO). It is updated and reissued every three years. The most recent update is the 1997 UBC.

The revised construction standards in updated versions of the UBC and other building codes apply to new construction and are not retroactive to address design deficiencies in older construction. Significant UBC changes in home earthquake design requirements over time have improved the performance of newer homes in recent California earthquakes. Table 2 lists the years that key earthquake design requirements related to home construction were first included in the UBC.

The Uniform Building Code Seismic Zone Map

The UBC Seismic Zone Map is used to determine two earthquake design factors: (1) the minimum level of earthquake side-to-side shaking, called ground acceleration, that must be used to calculate the structure's design forces, and (2) the need to include special earthquake resistant connections in the design. The UBC Seismic Zone Map divides the United States into zones of potential earthquake damage. Prior to 1976, the four UBC earthquake zones were Zone 0 (no damage), Zone 1 (minor damage), Zone 2 (moderate damage), and Zone 3 (major damage). In 1976, a Zone 4 classification (major damage caused by near-by fault movements) was added.

Earthquake design factors and special earthquake connection details are not reqired in UBC Seismic Zone 0 or Seismic zone 1. Increasing ground shaking values are used in the calculation of design forces in Seismic Zone 2, 3, and 4. Special earthquake connection details, however, are only required in Seismic Zone 3 and Seismic Zone 4. The lack of earthquake connection details and the lower force level required in UBC Seismic Zone 2 designs make buildings designed to these standards substantially less earthquake resistant than buildings designed to Seismic Zone 3 or Seismic Zone 4 design requirements.

Revisiions to the UBC Seismic Zone Map are based on information from geologists, seismologists, and engineers. Figure 3 shows significant changes to the UBC Seismic Zone Map from 1946 to 1988. Fig. 4 shows the 1997 UBC Seismic Zone Map.

Impact of UBC Seismic Zone Map Changes on Cascadia Region Design

Washington was included in UBC Seismic Zone 1 prior to 1952. Because the UBC does not specify earthquake design requirements for Seismic Zone 1, Washington homes built to UBC construction standards prior to 1952 were not required to meet the earthquake design requirements then being used in California. Revision of the UBC Seismic Zone Map in 1952 changed Washington state from Seismic Zone 1 to two Seismic zones: Seismic Zone 3 in Puget Sound and Seismic Zone 2 in the rest of the state. This revision was in response to the occurences of earthquakes causing significant damage in the region, most notably in 1946 and 1949. The 1952 UBC Seismic Zone Map adopted for Washington generally resulted in a tripling of the design force requirements for puget Sound and a doubling of force requirements for the rest of the state. In addition, the 1952 UBC required the design of special earthquake connection details in Puget Sound for the first time.

Adoption of Building Codes in the Cascadia Region

In 1955, the Washington State Legislature passed building standards that required hospitals, schools, buildings for public assembly, and publicly owned structures to be desgined and constructed to resist earthquakes. For all other buildings, however, the adoption of earthquake design standards depended upon local building departments. Nearly twenty years later, the legislature adopted the 1973 UBC as a minimum construction code for all buildings in communities throughout the state. (State Building Code Acts RCW 19.27 and 19.27.A, effective 1/1/75.)

Table 1 lists when (1) the UBC adopted special earthquake design requirements for home design, (2) the UBC was adopted as a Washington state construction standard for all communities, and (3) Seattle, Tacoma and Everett adopted special earthquake design provisions. Until 1975, communities generally adopted only sections of the UBC as ammendments to local codes rather than adopting all the UBC requirements. There is usually a delay of several years between the proposed change of local building codes and adoption of revised building codes. These delays reflect the need by local communities to review, amend, and adopt newly published standards into community building codes.

Changes to local building practice do not directly correspond to the date design requirements were included in state and local building codes. Building professionals familiar with earthquake damage in other parts of the country and concerned with the potential for earthquake damage in the Pacific Northwest, may include higher design forces and earthquake connection details in design and construction before these are required by state and community building codes. Often the local design community must be educated to understand the methods and reasons behind the changes and how to implement them into local design practice. Because of the complexity of code changes and variations in local building practice, local officials may have difficulty determining the exact design requirements that may have been used in the design of a specific home.

Earthquake Building Practice for Home Construction

In most cases, homes built before 1965 in Seattle, Everett, and Tacoma lack foundation anchor bolts. The bolts that were installed generally do not meet today's requirements for bolt size, spacing, and condition. Homes built between 1965 and 1975 *may* have foundation bolts, and those built after 1975 generally *will* have foundation bolts. Strengthening of the short wall that exists in some homes between the first floor and the top of the foundation wall, called the pony wall, generally did not occur in any Washington communitites until after 1975, and some homes built as recently as 1985 may lack proper pony wall strengthening as well.

Remember the exerpt above is from October 1999.

Therefore the references and present tense language is of that time-frame. IIRC there have been several programs and phases in Washington state to assist homeowners in retrofiting their older homes over the years (not unlike wind resistance retrofit programs in Florida). So, as far as your "anchor bolts" historical requirements question, as pertains to your location (Washington state) that should give you a decent historical perspective. You would, of course, need to review local code adoption/status for your specific location. Of course design requirements and code provisions continue to change beyond what was covered in this (now 11-year old) information series/brochure.

Here is a direct link to the brochure (clickable link) it is a pdf file:

http://www.co.pierce.wa.us/xml/servi.../impactbk1.pdf

Hope that helps.

P.S.

If I may, I highly suggest that you consider printing out and saving the brochure. Documents such as these have a tendancy to move, or disappear entirely and computers/disks have a tendancy to fail, crash, and technology, program versions, etc. have a tendancy to change. Was lucky enough to find similar locally hosted/version document on the www, searching via quoted phrases to track down a version you would be able to source directly.

And, there was nothing stupid about your question.

Finally, I did not address the current standards/code, sizing, spacing requirements for your region, nor when they may have been placed into effect.

HG

Thank you. I should of refined my search perameters. You were correct on your assumptions, stick built single family homes.

You're welcome Don.