Plumbing Top Out

Plumbing Top Out

What Is Plumbing Top Out?

Plumbing top out is one of the phases of plumbing 1 and is also called rough-in phase 2 whose responsible is a licensed master plumber 4 who is a professional that has specific studies 6 to become a Plumbing Technician 5 or has learned through apprenticeship 7 along with other minimum requirements to become a plumber 9. Plans for the plumbing top out phase must be submitted for approval at the state level 8 and requirements to obtain work permits or plumbing permitting 10.

The plumbing top out phase is defined as the stage where above-ground plumbing, i.e. water pipes, waste, and vent pipes are installed to the fixture outlets.  Done prior to covering and concealing walls, ceiling, and floor 3.

Plumbing top out is the arrangement of the piping network in walls and flooring above ground and out through walls and roofing before its coverage with wallboard. It occurs mainly in the MEP phase in construction projects where plumbing top out activities require to be scheduled.

It includes all supply lines and the Drain-Waste-Vent (DWV) lines that will be covered up. Furthermore, we should include in the plumbing top out phase the water lines pressurized, stub outs ok for fixture valves on trim out. Shower pans with standing water test and tubs installed.

Top out plumbing ensure that the water supply and drainpipe connections have been made throughout the frame of the house. 

The 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).

The plumbing top out phase will be completed basically when a draw inspection for the corresponding stage ensures that the plumbing component or network above-grade can be covered with the substrate material defined, such as insulation, framing, drywall, or concrete.

Plumbing top-out definition is subject to the terminology definition for the loan/draw agreement schedule for each individual plumbing project contract and particular terms of 203k when the project entails an FHA loan.

Plumbing top-out is located as the second stage of the plumbing project from an end-to-end point of view and takes place when the building or facility is still in the framing phase.

During this phase is where the drains, water lines, bathtubs and shower network, and ventilation pipes are installed.

The Drain-Waste-Vent (DWV) System is of course included too in this plumbing top-out phase. The drain-waste-vent system, also known as the sanitary system according to the industry standards, is all of the plumbing in your home minus the water supply system

Activities Required During The Plumbing Top Out Phase

During the plumbing top out phase, a plumber:

  • Creates holes in the walls, ceiling, or flooring for connection and attachment of the piping network to the fixtures.
  • Installation of the pipework necessary for the building’s different supply and waste systems.
  • Joining of pipelines through the utilization of welding tools, soldering equipment, or specific chemicals for plastic pipes. The plumber utilizes power tools for these activities.

Before you can install the drywall, you must also install the gas network. This is usually included in the rough-in plumbing stage but is sometimes outsourced to a different service provider if the plumber is not in possession of a gas ticket.

Ascertain that the plumber you choose examines everything prior to the closure of the walls.

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

Plumbing Top Out In The Context Of The Plumbing Phases

Plumbing new construction typically requires three stages of plumbing during the construction or remodel of a new space.

Underground Rough-In Phase

This step happens prior to pouring the foundation. A plumber must find the supply and waste connections and determine where these systems will enter and exit the building during the underground rough-in.

Plumbing Top Out Phase Or Above-Ground Rough-In

Aboveground Rough-In (Top Out Plumbing): This is the last stage, which involves installing plumbing vent pipes and connecting the underground pipes to the vents. Plumbers are required to do the following:

To connect pipes to fixtures, perforations in the walls, ceilings, and flooring as required for the installations.

Installation of the piping for the supply and waste system of the real estate object.

If the plumber is joining plastic pipes, specific chemicals will be required, not just welding equipment.

The ability to use power tools, such as torches, is required.

The third and last phase is the installation of plumbing fixtures and appliances throughout the newly constructed home.

Sources And References For Plumbing Top Out Phase Topic

  1. US Environmental Protection Agency. United States Environmental Protection Agency guidance from hotline compendium: lead ban. Washington, DC: US Environmental Protection Agency; 1988. Available from URL: [PDF – 5 KB].
  2. Uni-Bell PVC Pipe Association. Handbook of PVC pipe design and construction. Dallas: Uni-Bell PVC Pipe Association; 2001. Available from URL: [PDF – 247 KB].
  3. Occupational Safety and Health Administration. Safety hazard information bulletin on the use of polyvinyl chloride (PVC) pipe in above ground installations. Washington, DC: Occupational Safety and Health Administration; 1988.
  4. Copper Development Association. Copper in your home: plumbing, heating, cooling. New York: Copper Development Association; no date. Available from URL:
  5. Plastic Pipe and Fittings Association. Cross-linked polyethylene. Glen Ellyn, IL: Plastic Pipe and Fittings Association; no date. Available from URL:
  6. NAMCO. Determine the total fixture unit load. Dallas: NAMCO; no date.  Available from URL:
  7. Public Health-Seattle and King County. Public health plumbing program: water supply fixture units (WSFU) and minimum fixture branch pipe sizes. Seattle, WA: Public Health-Seattle and King County; no date. Available from URL:
  8. US Environmental Protection Agency. Developing water system financial capacity. Washington, DC: US Environmental Protection Agency; 2002. Available from
    URL: [PDF – 2.19 MB].
  9. US Environmental Protection Agency. Water and wastewater pricing. Washington, DC: US Environmental Protection Agency; no date. Available from URL:
  10. US Environmental Protection Agency. Using water wisely in the home. Washington, DC: US Environmental Protection Agency; 2002. Available from URL:
  11. Energy Efficiency and Renewable Energy Clearinghouse. Demand (tankless or instantaneous) water heaters. Merrifield, VA: Energy Efficiency and Renewable Energy Clearinghouse; no date. Available from URL:
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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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