Drain-waste-vent systems

摘要

Although hidden behind walls and in floors and ceilings, the pipes that make up a house's drain-waste-vent (DWV) system are the balance of the plumbing equation. They are the exit for the water provided through the supply lines, they carry waste from the toilet, and they connect to outside air for venting sewer gas and relieving pressure. These relatively large-diameter pipes rely solely on gravity, but they aren't easily routed through the structure of a house. With three chapters in the IRC devoted to DWV systems, not to mention the tables and examples illustrated in the appendix, there is a lot to know about the layout and installation of such a system. Pipe sizes that vary based on usage; routes through framing bays that may already be packed with other mechanicals; pitch tolerances of plus or minus just ¼ in. per ft.; fittings with subtle differences in inlets, outlets, and applicability; and an array of minimums and maximums to consider when it comes to tying everything together are just a handful of the many situations, rules, and restrictions plumbers must understand.