Modern Plumbing 9e Page 316 (330 of 576)

Copyright Goodheart-Willcox Co., Inc. 316 Section 3 Plumbing System Design and Installation Therefore, if the center-to-center dimension is known, the length of pipe needed can be determined by subtracting the laying length of the fitting at each end of the pipe. Laying lengths for common types of fittings are given, along with the fitting allowances, later in this chapter. Various combinations of these measuring techniques are used. For example, you can measure face-to-centerline, face-to-shoulder, or shoulder-to-centerline. The key is to remember that any measurement taken to the face of a fitting requires you to add the appropriate fitting al- lowance. Any measurement taken to the centerline of a pipe requires you to subtract the laying length for the fitting to be installed. 21.3 Overview of DWV Installation The preparatory work described in Chapter 20 pro- vides an overall understanding of the DWV system. Based on this understanding, it is possible to carry out the installation in an efficient manner. Make sure you understand the general plan for the DWV system. Refer again to the sketch in Figure 21-1. Recall that it shows the DWV system for a one-story house, with laundry facilities in the basement and two bathrooms and a kitchen on the main floor. The fixtures to be installed and the size of the DWV piping are noted on the sketch. As you read the rest of this section, refer to Figure 21-1 to keep the overall installation in perspective. This installation requires two stacks that extend through the roof. The horizontal runs from these stacks will join below the basement floor and connect to the building sewer near the point where it enters the building. Note that a floor drain is to be connected to the horizontal drainpipe going to the kitchen/laundry stack. It may be helpful to think of the installation in three sections: 1. The horizontal runs below the basement floor. 2. The DWV piping for the bathrooms. 3. The DWV piping for the kitchen and laundry areas. If more than one plumber is working on the job, the work could be divided among the crew members on this basis. Code Note IRC and IPC Note IRC Chapter 30, Sanitary Drainage, includes most of the code requirements for DWV piping. These requirements include everything from materials, DWV design and sizing, sumps, to backwater valves. IPC Chapter 7, Sanitary Drainage, includes many of the same categories of requirements for DWV piping. Assuming that the openings have already been cut and the needed structural modifications completed, put a length of the correct size DWV pipe through the openings in the floor for each of the stacks and extend the pipe to the basement floor. Working from the basement, plumb the stacks to locate one end of the horizontal drain/waste pipe to be installed below the basement floor. An alterna- tive is to suspend a plumb bob through the center of the opening in the sanitary tee to the top of the fittings at the base of the stack, Figure 21-4. The drawing shows that the Code Note IRC Note IRC Chapter 30, Section P3002 provides the requirements for the type of pipe and fittings that can be used in the DWV piping. Section 3003 gives the requirements for joints and connections. Block Sanitary tee Plumb bob WYE String line at top of finished floor 1/8th bend Concrete Cleanout Dirt floor Stud Floor joist Goodheart-Willcox Publisher Figure 21-4. To locate the fitting at the base of the stack, suspend a plumb bob through the center of the sanitary tee. Concrete can be placed later to provide solid support for the weight of the stack.

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Copyright Goodheart-Willcox Co., Inc. 316 Section 3 Plumbing System Design and Installation Therefore, if the center-to-center dimension is known, the length of pipe needed can be determined by subtracting the laying length of the fitting at each end of the pipe. Laying lengths for common types of fittings are given, along with the fitting allowances, later in this chapter. Various combinations of these measuring techniques are used. For example, you can measure face-to-centerline, face-to-shoulder, or shoulder-to-centerline. The key is to remember that any measurement taken to the face of a fitting requires you to add the appropriate fitting al- lowance. Any measurement taken to the centerline of a pipe requires you to subtract the laying length for the fitting to be installed. 21.3 Overview of DWV Installation The preparatory work described in Chapter 20 pro- vides an overall understanding of the DWV system. Based on this understanding, it is possible to carry out the installation in an efficient manner. Make sure you understand the general plan for the DWV system. Refer again to the sketch in Figure 21-1. Recall that it shows the DWV system for a one-story house, with laundry facilities in the basement and two bathrooms and a kitchen on the main floor. The fixtures to be installed and the size of the DWV piping are noted on the sketch. As you read the rest of this section, refer to Figure 21-1 to keep the overall installation in perspective. This installation requires two stacks that extend through the roof. The horizontal runs from these stacks will join below the basement floor and connect to the building sewer near the point where it enters the building. Note that a floor drain is to be connected to the horizontal drainpipe going to the kitchen/laundry stack. It may be helpful to think of the installation in three sections: 1. The horizontal runs below the basement floor. 2. The DWV piping for the bathrooms. 3. The DWV piping for the kitchen and laundry areas. If more than one plumber is working on the job, the work could be divided among the crew members on this basis. Code Note IRC and IPC Note IRC Chapter 30, Sanitary Drainage, includes most of the code requirements for DWV piping. These requirements include everything from materials, DWV design and sizing, sumps, to backwater valves. IPC Chapter 7, Sanitary Drainage, includes many of the same categories of requirements for DWV piping. Assuming that the openings have already been cut and the needed structural modifications completed, put a length of the correct size DWV pipe through the openings in the floor for each of the stacks and extend the pipe to the basement floor. Working from the basement, plumb the stacks to locate one end of the horizontal drain/waste pipe to be installed below the basement floor. An alterna- tive is to suspend a plumb bob through the center of the opening in the sanitary tee to the top of the fittings at the base of the stack, Figure 21-4. The drawing shows that the Code Note IRC Note IRC Chapter 30, Section P3002 provides the requirements for the type of pipe and fittings that can be used in the DWV piping. Section 3003 gives the requirements for joints and connections. Block Sanitary tee Plumb bob WYE String line at top of finished floor 1/8th bend Concrete Cleanout Dirt floor Stud Floor joist Goodheart-Willcox Publisher Figure 21-4. To locate the fitting at the base of the stack, suspend a plumb bob through the center of the sanitary tee. Concrete can be placed later to provide solid support for the weight of the stack.

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Copyright Goodheart-Willcox Co., Inc. Chapter 21 DWV Pipe and Fitting Installation 315 additional drain to be roughed-in for the dishwasher. The sink/dishwasher branch needs to be 1 1/2″ because this is the diameter of the sink P-trap. The horizontal pipe that joins the stack carries 2 d.f.u and needs to be 1 1/2″ in diameter. Since the vertical drain pipe that ex- tends to the laundry room in the basement also has a load of 2 d.f.u., it must to be 1 1/2″in diameter. The branch to the laundry tub has a load of 2 d.f.u. and must be 1 1/2″ in diameter. A washing machine has a load of 2 d.f.u. Therefore, the standpipe must be 1 1/2″ in di- ameter. The total load on the horizontal pipe connect- ing with the main building drain is 5 d.f.u. This pipe can be 2″ in diameter. The total load on the last section of DWV pipe inside the building is 13 d.f.u.. Therefore, this pipe also needs to be 3″ in diameter. 21.2 Measuring Pipe Accurate measurements are critical to the success of every plumbing installation. It is often difficult, if not impossible, to directly measure the length of pipe required to join two fittings. Techniques that require knowledge of fitting allowances and the laying length of fittings must be used. This introduction to these methods will help you understand the remainder of this chapter. Measurements to determine the length of pipe are taken in one of three ways: ■ ■■ Face-to-face. ■■ Shoulder-to-shoulder. ■ Center-to-center. Figure 21-2 illustrates the three methods. The face- to-face method requires that the plumber know the fitting allowance for the type and size of fitting being installed. This information is provided with the proce- dures for installing each of the different types of pipe. Shoulder-to-shoulder dimensions provide a direct reading of the actual length of pipe required. There- fore, they are more accurate and save time because ad- ditional calculations are not required. However, this method is useful only with DWV fittings. Pressure fit- tings do not have shoulders. Center-to-center measurements require the plumber to know the laying length of the fitting. The laying length is the amount of a run of pipe, measured along the cen- terline, that is taken up by the fitting, Figure 21-3. Code Note IRC Note IRC Chapter 31 provides the details of the code related to vents. Requirements described include, but are not limited to, design, sizing, protection of extension through the roof in freezing conditions, wet venting, circuit venting, and common vents. Measure from face to face and add fitting allowance for each fitting. Measure from center to center and subtract laying length for each fitting. Face-to-Face Measure from shoulder to shoulder distance (DWV only). Shoulder-to-Shoulder Center-to-Center Goodheart-Willcox Publisher Figure 21-2. Three ways to determine the length of pipe needed between two fittings. Laying Length Laying Length Center-to-Center Laying Length Laying Length Goodheart-Willcox Publisher Figure 21-3. Laying length is the amount of a run of pipe, measured along the centerline, that is replaced by a fitting.

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Copyright Goodheart-Willcox Co., Inc. Chapter 21 DWV Pipe and Fitting Installation 317 opening in the wye that will be the cleanout is flush with the top of the finished concrete floor. Check the section drawings for the foundation to determine how much the concrete floor is to be above the footings. It may be nec- essary to stretch a string line to represent the top of the basement floor to obtain an accurate height for the wye. It is better for the wye to be slightly higher than necessary so the cleanout plug can be easily installed and removed. Some digging will be necessary to place the wye and 1/8th bend at the correct elevation. To locate the horizontal waste pipe, stretch a string line from the base of the bathroom stack to the place where the building drain will extend outside the foundation to connect with the building sewer. A shallow trench will need to be dug along this line so that the waste pipe can be installed with the correct slope. A second string line can be run from the base of the kitchen/laundry stack to the point where it will join with the first horizontal waste line. (Refer to Figure 21-1.) This joint must be made with standard fittings, so the intersection should be at an angle of 30° to 45° to allow a standard wye and a bend of the correct curve to be used. Once the location of the horizontal pipe is determined, a trench can be dug to permit its installation. Trenches must be sloped so they provide a fall of 1/4″ per foot of run. Generally, the top of the concrete floor for a basement will be 4″ above the top of the footings. This dimension should be checked so the depth of the trench can be Green Note Minimizing Pipe and Fitting Waste Plumbers can do several things to minimize waste of pipe and fittings. First, and possibly most important, is for the plumber to understand what the job requires and plan the installation to avoid the use of excess pipe and fittings. Saving even a few feet of pipe or several fittings on every job creates large savings during a plumber’s career. following practices help minimize waste: ■The ■ Storing and handling pipe and fittings so they are protected from damage and can be located easily. This practice contributes to efficiency and encourages the use of short lengths of pipe. ■ ■ Checking measurements and calculations before cutting pipe to minimize errors, thus reducing waste. ■ ■■ Using as much of each length of pipe as practical. ■ Selecting the most appropriate fitting rather than combining two or more fittings. Using a reducing tee rather than a standard tee and a reducer is an example of this practice. ■ ■ Recycling any unusable or damaged fittings and short lengths of pipe. Can you think of other things you could do to mini- mize amount of pipe and fittings that are wasted? determined. A short trench will also be needed for the floor drain to connect to the 2″ pipe using a wye. 21.3.1 Installing a Stack While the trenches are being dug, work can begin on the stacks. First, consider the kitchen/laundry DWV piping. Figure 21-5 provides a sketch of this pipe and fittings to be used. The names and dimensions of the fittings are given in the table included with the sketch. Code Note IRC Note IRC Chapter 30, Section P3005.2, describes the requirements for cleanouts. These requirements address changes in direction, maximum distance between cleanouts, and size and accessibility of cleanouts. Details are given regarding each of these topics. Goodheart-Willcox Publisher Figure 21-5. Schematic drawing for laundry/kitchen stack. Table identifies the fittings needed. A B D C E F H D G To 3 × 3 × 2 wye F F 2° 1½° 1½° 2″ 2° 1½° 2° Label Quantity Description A B C D E F G H 1 1 1 2 1 3 1 1 2″ floor drain 2 × 2 × 2 wye 2″ long-radius 90° ell 2 × 2 × 1½ san. tee 1½″ P-trap 1½″ 90° ell 2″ test tee w/ cleanout plug 2 × 1½ × 1½ san. tee

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Page 2Section 1 Introduction to Plumbing click to expand contents

Page 176Section 2 Plumbing Systems click to expand contents

Page 272Section 3 Plumbing System Design and Installation click to expand contents

Page 454Section 4 Plumbing Services click to expand contents

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