08-04 Use of 90 degree elbow

Question: 08-04Code Section: 7Date: 3 February 2008OBC 2006 Reference:;

Question: We were always taught that the rule was 1-90 and two 45’s when offsetting. In the photo the kitchen sink (with a Dishwasher) was roughed in with 2″ ABS, runs 20′ from right to left and in order for the plumber to get around the 5″ heating run he used two 90’s in lieu of two 45’s. In my opinion the two 90’s would reduce the flow and allow solids to build up in the horizontal drainage piping. If we refer to page 12 of the appendix under A- I do not see two 90’s being used in any of the offsets. The plumber advises me that this is a common practice to get around heating ducts and I advised him that this was unacceptable. I await your response.

Interpretation: As determined in A06-31, if the fitting is certified to the CSA standard, then it would be in compliance with therefore could be used downstream of the vent without too many restrictions. Many members of the Code Tech Committee feel that the use of CSA certified short radius 90° do not appear to turn a full 90 degrees and are published as not certified vent 90° in manufacturer catalogues. Note that a cleanout is required to be installed on the horizontal pipe 6m downstream as per …. and the maximum spacing between cleanouts on horizontal pipe shall be, (a) in the case of a sink waste pipe, 6 m.

Interpretation: Approved at AMES 2008