4.1.2 Underground DWV pipe outside foundation:
•The materials used for outside the foundation can come from the IPC Table 702.3 Building Sewer Pipe which allows such piping as SDR35 (PVC) which is not allowed within the building foundation.
•The materials found in IPC Table 702.2 Underground Building Drainage and Vent Pipecan be used inside or outside the foundation. If the materials found in Table 702.2 are used clearances to water mains required in IPC Section 603.2 are eliminated and the piping could actually be located in the same trench.
•Unlike the outside storm water piping the outside sewer piping is required to be tested.
4.2.1 Rough plumbing underground DWV and Storm piping inside the building foundation:
•“Proper pipe bedding”***
•Was a plan and set of specifications submitted for the project? If a plan and specification was submitted was an installation detail provided for the installation of underground piping? Details provided are usually very specific and must be followed.
•All installed piping must be properly supported. The code requires solid and continuous load-bearing support shall be provided. If the observed piping elevation is deep the underground may have to be installed and tested in stages to achieve proper piping support and ultimately code compliance.***
•“Check piping layout”
•Some materials are only good for outside the structure such asSDR35 piping for sewer work which cannot be installed inside the structure or foundation.
•Problems such as flat dry venting below the fixture flood rim, missing code required cleanouts, and exceeding fixture outlet to trap weir distance are often encountered.
•Check for correct method of material joining. IPC Sec. 705
Underground plumbing and storm piping cont.
•IPC Section 306 Trenching, Excavation and Backfill
•306.1 Support of piping The piping must be supported throughout its entire length!
•306.2 Trenching and bedding Solid and load bearing support required. Bell and coupling holes may be provided to accommodate the joining of the pipes. Piping SHALL NOT be supported on blocks to grade. A common unacceptable practice is to support piping on small piles of sand etc. ***