The IAPMO Standards Council has handed down a decision on a Tentative Interim Amendment (TIA) to the 2006 Uniform Plumbing Code (UPC). The council issued TIA UPC-021-06 to better clarify a method of horizontal wet venting installation and more clearly define what constitutes a bathroom group.

In the TIA, a bathroom group is now categorized as “A group of fixtures consisting of a water closet, one or two lavatories, and either a bathtub, a combination bath/shower, or a shower and may include a bidet and emergency floor drain.”

This section about wet venting installation was amended to specifically define the fixtures permitted to discharge into this type of configuration, such as “Water closets, bathtubs, showers and floor drains.”

“Unless the code language is clearly written and precise, it’s very difficult for inspectors in the field to enforce it,” said Lynne Simnick, IAPMO director of Code Development. “The changes made have answered those concerns.”

This is the third TIA approved for the 2006 UPC. TIA UPC-012-06 was approved on Feb. 7, 2006, and TIA UPC-016-06 on Aug. 28, 2006.

To examine TIA UPC-021-06 in its entirety, please direct your Web browser to

TIAs are proposals based on the determination of an emergency nature requiring prompt action to amend code that contains an error or omission that was overlooked during the regular code development process, contains a conflict within the document or with another IAPMO document, or to correct a hazard, promote an advancement in safeguarding the public or provide an opportunity to correct an adverse impact on a product or method of installation.