To G or not to G: that is the question
Revision G standard set for January introduction, but acceptance may take up to three or more years

November 10, 2005 -- TIA/EIA-222-G will take effect January 1, 2006, but building departments may be years away from enforcing the long-awaited revision of the structural standard for antenna supporting structures and antennas.

The short answer for the lengthy delay: TIA/EIA-222-G is a voluntary standard and has no legal bearing. It only gains formidable strength if it's referenced by the International Building Code (IBC) or any other code, and the code is adopted by a permitting jurisdiction.

But the code referencing and adoption process is a long, sometimes arduous procedure that can oftentimes take years.

The first IBC Code (2000) was the culmination of an effort that started in 1997 by representatives of Building Officials and Code Administrators International, Inc. (BOCA), International Conference of Building Officials (ICBO) and Southern Building Code Congress International (SBCCI) to have a comprehensive set of unified regulations.

The new IBC 2003 has been adopted by the majority of the country and has become the industry bible, but it references TIA/EIA-222-F. A new edition is promulgated every three years. The TR14.7 editorial committee worked hard to polish up seven years of dedication of more than 50 members of the sub-committee that maintains the TIA-222 structural standard so that it could be referenced in IBC 2006.

Unfortunately, voting members of the IBC did not have enough time to thoroughly review the new tower standard and did not include it in their new code to be effective next year. Instead, Revision F will still be referenced, said Tom Hoenninger, TR14.7's liaison to the IBC and chief engineer for Stainless LLC.

Tom said that there is a 2006-2007 development cycle that will allow for the publishing of a supplement to IBC2006 in June of 2007. He believes that it should not be a problem for the committee to be able to thoroughly review Revision 222G and recommend it for inclusion in the IBC supplement.

If approved, then Revision G will become the national standard. However, Tom points out that it might not be quickly adopted by building departments and it could be another couple of years before it is fully accepted by permitting jurisdictions.

He said that in the past Stainless LLC has had to design towers to earlier codes although a newer revision had been available for a few years, but the permitting community had never adopted it.

“Rev G can be considered more stringent than Rev F, and permitting officials tend to prefer the more stringent provisions, if they are aware of them,” explained Simon Weisman, a member of the TR 14.7 sub-committee.

It is expected that the approval process will be shortened considerably since the three second gust wind, the new ice loads, the use of LRFD design procedures, and the seismic provisions were all introduced in Revision G to be more like those that the building codes have and are now accepted by building officials, said Simon whose tower analysis software is used by numerous fabricators and engineering firms.

What's a poor spec writer to do?
The entire standard or relevant parts of Revision G can be used as a supplement to a specification that also requires the structure to meet jurisdictional requirements. Purchasers can also request that the tower meet Revision F, if that is the applicable code, as well as Revision G. Whereas the new revision of the tower standard may not currently having legal bearing, it gets all of the strength it needs when the purchaser references it.

Stainless LLC is currently providing quotes for guyed towers under both F and G revisions, Tom said. In reviewing initial engineering runs for tall towers, he has found that Revision G appears to be providing a lighter guying system than Revision F in most comparisons. However, with mandatory ice loading in Revision G and pattern loading at the top of the structure, the mast is generally heavier. He said that they have designed a number of structures for Revision F which will provide for a heavier guying system, but they must then be reviewed under Revision G to make the necessary changes to the mast. They'll then look at it under Revision F again to ensure that it hasn't changed the guying system. He said that Revision G is affecting the tops of tall towers, emphasizing that smaller structures may not feel the same impact.

Engineer Stephen Yeo of Sabre Communications Corporation says that he has found that after reviewing initial engineering runs they have done on smaller towers that Revision G structures are slightly heavier than those designed under Revision F. However, he said that Sabre hasn't done enough Revision G towers to be certain of the trends.

Valmont Communications' Myron Noble agrees that it is too early to develop meaningful data based upon the limited comparisons that have been made by his engineering group.

David Brinker of Radian Communication Services/Rohn Products, an engineer and member of TR14.7's executive task group, has been an active participant during numerous revisions of the standard. He too believes that it is too soon to draw comparisons between the two revisions since Revision G allows the purchaser multiple tower design options that are not available with Revision F.

Although he doesn't champion the military maxim of hurry up and wait, he does believe that there may be a hidden benefit in not getting immediate acceptance by the IBC.

"I think it's good that the whole industry is going to have to take a little bit more time to get used to this as opposed to if the IBC would have adopted it; then it would have been more of a rush in a panic mode," David said.

Although some tower manufacturers and engineering firms have the design software in place to easily run both revisions for their clients, others are trying to incorporate Revision G into their existing programs, a process that could take months.

One leading tower analysis software, GUYMAST-G, gave fabricators and engineering consulting groups a head start when it was shipped in August.

When Revision G becomes the national standard any new collocation will require the existing tower to be reanalyzed under Revision G. Some of the larger tower purchasers have expressed an interest in having their new structure meet Revision G plus the prevailing standard so that they will have a greater comfort level that their design will allow for additional tenants.

For additional information about the seventh revision of the Telecommunications Industry Association standard, please visit Tower Design Checklist  . The standard is available at www.tiaonline.org in an electronic file or hard copy for $361.

Questions and comments about Revision G can be posted in our forum .

Craig Snyder, President of Sioux Falls Tower & Communications, serves as chairman of the TR 14.7 Committee. The industry is indebted to Craig and the following professionals who gave of their time and knowledge to assist in the publication of this comprehensive standard.