Copyright Goodheart-Willcox Co., Inc. Chapter 21 DWV Pipe and Fitting Installation 319 (12″ – 3/4″). It may be helpful to lay the two sanitary tees on a flat surface in the correct position and mea- sure the face-to-face length of pipe required. Add the appropriate fitting allowance and cut the needed length of pipe (1 3/8″ + 1″ + 1″ = 3 3/8″). A test tee for the cleanout can be joined to the sani- tary tee with a 2 1/4″ length of pipe. This is two times the fitting allowance plus 1/4″. A trial assembly of these components will allow the dimensions to be checked before final assembly. It may be possible to delay installing the horizontal pipes to the standpipe and laundry tub until the con- crete floor has been poured. This will make it easier for the concrete finisher and may prevent damage to these pipes. If this installation is delayed, the sanitary tee in- lets should be plugged to prevent anything from getting into the piping. This temporary plug will also prevent 2uni2032-6° Flat surface A Flat surface B To building sewer String line for top of concrete floor 8° 4° Mark the centerline of the P-trap Mark centerline of sanitary tee Fall @ ¼° per foot of run: 2½uni2032 × ¼° per ft = 5⁄8° total fall 2uni2032-6° A B C 45⁄8° Ground line Top of ground Goodheart-Willcox Publisher Figure 21-7. Locating pipe and fittings for the washing machine standpipe. A—Determining fitting centerlines. B—Marking fitting locations. C—Calculating fall. To building sewer 3uni2032 String line for top of concrete floor 90° ell for stub-out 4° 12° 11¼° Mark centerline of sanitary tee Mark centerline of 90° ell 13⁄8° Top of ground Goodheart-Willcox Publisher Figure 21-8. Locating pipe and fittings for the laundry tub.