Plumbing Top Out

Plumbing Top Out

What Is Plumbing Top Out?

Plumbing top-out is the stage of plumbing that occurs when a home is in its frame stage. There are three stages of plumbing typically in construction. Plumbing rough (prior to the foundation being poured); plumbing top out (bringing ground plumbing up through the vents); and finally plumbing trim (installing fixtures).

Plumbing top out is the arrangement of the piping network in walls and flooring above ground and out through walls and roofing before its cover with wall board.

At this stage, you’ll need to install all of your drains and vent pipes as well as the water lines.

You will also need to install all of the bathtubs, showers, or shower bases that you have going into your house.  This has to be done regardless of whether you are building a new home, basement development or renovating your house.

During the plumbing top out phase, a plumber:

  • Cuts holes in wall, ceiling, or floor to attach or hang pipes for connection to fixtures
  • Installs the pipe for the building’s various supply and waste system
  • Uses welding tools, soldering equipment to join pipe runs, or special chemicals for plastic pipes
  • Operates power threading machines, propane torches, and other power tools

Before the drywall can be put up you will need all of your gas lines installed as well.  This is always part of the rough in plumbing stage, but sometimes left to another contractor if the plumber does not have a gas ticket.

Make sure the plumber you hire tests everything before the walls are closed up.

Plumbing Top Out Naming Convention

Plumbing top out is also referred to as an “above-ground rough-in”.

However, official inspection checklists of County Public Works refer to the below-grade as a “rough-in”, and the above-ground as plumbing top out.

Furthermore, this is also the name utilized in foundation inspections and included in the checklists to tick at the end.

Some people in the trade, mostly plumbers and plumbing suppliers would refer to the “rough-in” as all the work below grade

Plumbing Top Out Inspection Checklist

To understand better what is plumbing top out, let´s see an arrangement of typical plumbing top out checklists.

  • The contractor or person doing the work has reviewed the approved plans and can ensure that the construction being inspected is consistent and ready for inspection.
  • Job address is posted in a visible location, and drains are properly sized. IRC R319.1, UPC Table 703.2
  • Drains, waste and vents (DWV) have been water tested with a 5-foot head for 15 minutes or air tested at 3 pounds per square inch (psi) for 15 minutes. UPC-LA 712.1
  • If drain loop method is being used, fittings are of drainage type. UPC-LA 909.0
  • Island drain serves no other fixture upstream from return vent. UPC-LA 909.0
  • Island sink cleanout is in vertical section of foot vent. UPC909.0
  • Back-to-back fixtures have double fixture fitting. UPC704.2
  • Changes in sanitary drainage from vertical to horizontal or horizontal to horizontal enter through 45-degree wye branches. UPC 706.3, 706.4
  • Double sanitary tees option was used when barrel of stack is 2 pipe sizes larger than inlets for connecting with a vertical stack. UPC 706.2
  • When plastic or copper plumbing is within 1 inch of face of framing, 18-gauge nail plates are installed. UPC 312.9
  • Plastic lines are supported every 4 feet and at each horizontal branch connection. UPC Table 313.3
  • Vertical plastic lines are supported at base and each floor, and mid-story guides are provided. UPCTable 313.3
  • Waste pipes installed outside or in exterior walls are protected from freezing where necessary. (i.e., Ptraps). UPC 312.6
  • For each trap protected by a vent, the vent system is designed to prevent a trap seal from being exposed to a pressure differential that exceeds 1 inch water column on the outlet side of the trap. UPC 901.3
  • Unless prevented by structure, the vent rises vertically 6 inches above the floor level rim before continuing to horizontal. UPC 905.3
  • Takeoffs for vents are above the weir. UPC 905.5
  • Vent pipe located below flood level of rim is drainage pattern. UPC905.3
  • Standpipe receptor is greater than 18 inches and less than 30 inches above trap. UPC 804.1
  • Shower area is at least 1,024 square inches, with a 30-inch clear diameter to 70 inches from the floor of the shower. UPC 411.7
  • Slope underlayment (shower pan) is ¼ inch per foot. UPC412.6
  • Combustion air meets appliance manufacturer requirements. UPC 506
  • Temperature pressure relief valve is in place. UPC 608.5
  • Pressure temperature relief line terminates outside 6 to 24 inches from ground pointing down, is made of approved material, and drains at least ¼ inch per foot with no reductions. UPC608.5 Bonding required is used if CSST (Corrugated Stainless Steel Tubing) is used as gas piping. UPC1211.2
  • Gas system is sized according to UPC Chapter 12, and test is performed on gas rough system UPC-LA 1203.3.2

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BY M. Kogan

Hello, I am Marcio. I am an architect and designer, alma mater is Mackenzie. Retired in theory, but an architect never retires completely. Along with architectural projects, I am a filmmaker and have completed some short documentaries. Filmmaking and design are my passions. In HomeQN I write about home decoration and foundations. The goal is to teach homeowners to DYI as much as possible, and when this is not possible, enable them through knowledge, to evaluate service quotations and choose the best service technicians.

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