the pipe. Between ⅛ ″ and ¼″ of fall per foot of run is generally required by code. Excavating the trenches for the horizontal runs of the drain/ waste piping must be done carefully so that the correct fall is produced. It is often easier to dig extra deep and use fine gravel or sand fill to provide solid, properly sloped support for the pipe. The slope can be measured with a builder’s level or transit, but a 4′ or 6′ carpenter’s level is adequate for most residential installations. Figure 19-13 shows how you can check a level to determine how much the “bubble” should be off- center for a given fall. Once the level has been checked, it can be used (without the block) and the pipe adjusted until the bubble is in the desired position. For a lengthy run of pipe, lay a length of pipe into the partly dug trench and check the fall with the level. Remove the pipe and continue digging and checking until the needed fall is achieved. This process is repeated until the trench is completed. A trial assembly of the pipe and fittings will usually reveal some need for additional digging and filling of low spots. The wye and the pipes that join with it must be aligned at the correct angle so the joints will fit correctly. In cases where Once the flashing is in place, determine the length of the stack by extending a tape measure from the roof to the sanitary tee. Two people are needed to install the stack. One pushes the pipe through the flashing from below, while the person on the roof holds the flashing in place so it will not be damaged in the process. Most stack flashing is fitted with a plastic/rubber collar that seals around the pipe. If this is not the case, apply caulking at the joint between the flashing and the stack to prevent water from entering. Fixtures with concealed slip-joint con- nections, such as a P-trap, require an access panel that is at least 12″ in its smallest dimension. An example would be a bathtub. Installing Horizontal Drain/ Waste Piping The key concern when installing horizontal runs of drain/waste piping is maintaining the required fall for the entire length of the run. If there is too little fall, the waste will not flow through the pipe. If there is too much fall, the liquid will flow so fast that the solids will be left behind to clog “½ bubble off” “Bubble off” Block 1. Place the level on a flat surface. If the reading is not level, shim one end of the tool until it reads level. 2. Place a block under one end of the level to simulate a fall of ¼″ per foot: Length of Thickness level of block 1′ ¼″ 2′ ½″ 4′ 1″ 6′ 1½″ 3. Check position of the bubble. This is where the bubble needs to be for the pipe to be at a fall ¼″ per foot of run. Goodheart-Willcox Publisher Figure 19-13. The bubble of a level can be used to indicate the degree of fall of a horizontal run of pipe. Flashing: Material (often a formed metal product) that is used to prevent water from leaking into the building around the stack. Chapter 19 DWV Pipe and Fitting Installation 307 Copyright Goodheart-Willcox Co., Inc.
Modern Plumbing, 8th Edition Page 307 (321 of 624)
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the pipe. Between ⅛ ″ and ¼″ of fall per foot of run is generally required by code. Excavating the trenches for the horizontal runs of the drain/ waste piping must be done carefully so that the correct fall is produced. It is often easier to dig extra deep and use fine gravel or sand fill to provide solid, properly sloped support for the pipe. The slope can be measured with a builder’s level or transit, but a 4′ or 6′ carpenter’s level is adequate for most residential installations. Figure 19-13 shows how you can check a level to determine how much the “bubble” should be off- center for a given fall. Once the level has been checked, it can be used (without the block) and the pipe adjusted until the bubble is in the desired position. For a lengthy run of pipe, lay a length of pipe into the partly dug trench and check the fall with the level. Remove the pipe and continue digging and checking until the needed fall is achieved. This process is repeated until the trench is completed. A trial assembly of the pipe and fittings will usually reveal some need for additional digging and filling of low spots. The wye and the pipes that join with it must be aligned at the correct angle so the joints will fit correctly. In cases where Once the flashing is in place, determine the length of the stack by extending a tape measure from the roof to the sanitary tee. Two people are needed to install the stack. One pushes the pipe through the flashing from below, while the person on the roof holds the flashing in place so it will not be damaged in the process. Most stack flashing is fitted with a plastic/rubber collar that seals around the pipe. If this is not the case, apply caulking at the joint between the flashing and the stack to prevent water from entering. Fixtures with concealed slip-joint con- nections, such as a P-trap, require an access panel that is at least 12″ in its smallest dimension. An example would be a bathtub. Installing Horizontal Drain/ Waste Piping The key concern when installing horizontal runs of drain/waste piping is maintaining the required fall for the entire length of the run. If there is too little fall, the waste will not flow through the pipe. If there is too much fall, the liquid will flow so fast that the solids will be left behind to clog “½ bubble off” “Bubble off” Block 1. Place the level on a flat surface. If the reading is not level, shim one end of the tool until it reads level. 2. Place a block under one end of the level to simulate a fall of ¼″ per foot: Length of Thickness level of block 1′ ¼″ 2′ ½″ 4′ 1″ 6′ 1½″ 3. Check position of the bubble. This is where the bubble needs to be for the pipe to be at a fall ¼″ per foot of run. Goodheart-Willcox Publisher Figure 19-13. The bubble of a level can be used to indicate the degree of fall of a horizontal run of pipe. Flashing: Material (often a formed metal product) that is used to prevent water from leaking into the building around the stack. Chapter 19 DWV Pipe and Fitting Installation 307 Copyright Goodheart-Willcox Co., Inc.
