08-12 Relief vent requirements

Question: 08-12Code Section: 7Date: 23 March 2008OBC 2006 Reference: 7.5.4.5.(1)

Question: 7.5.4.5.(1) explains very well how to connect fixtures to a relief vent, only 2 fixtures, connected to the vertical section of the vent pipe, totalling not more than 1 1/2 FU ea. I have a problem with 7.5.3.1.(4) where it states that a soil or waste pipe (usually means one fixture connected to it) having a load not greater than 6 FU (7.5.4.5. says 3 FU max). Is this a conflict? Which takes precedent? Similar issue was raised regarding 7.5.4.5. and 7.4.2.1.(1)(e) where 7.5.4.5. was deemed to take precedent. Is this the same?

Interpretation: 7.5.3.1(4) (ie. the 6 fixture unit rule) superseded the other and a change would be forthcoming one day to correct this, keeping in mind that the relief vent only has the restriction of 6 fixture units, which means, that it could be a soil stack going up 2 floors or more. Therefore, Clauses 7.4.2.1.(1)(e) to (g) will be proposed to be removed with the next Code change cycle, hopefully followed by the removal of the wordings “relief vent” and change the “sanitary T fitting” to “conforming to Table 7.2.4.5.” as shown in Article 7.5.4.5. of the 2006 Building Code.

Interpretation: Approved at AMES 2008 (Code Change Proposal Pending)