Reference: 2018 International Plumbing Code (IPC) & 2018 International Fuel Gas Code (IFGC)
Learning Objectives
Upon completion of this chapter, the candidate will be able to:
7.Navigate the structural hierarchy of the IPC and IFGC to locate definitions, administrative rules, and technical requirements rapidly.
8.Apply the fundamental principles of plumbing design, including fixture location, venting, and trap seal protection, as mandated by Chapter 1 and Chapter 9 of the IPC.
9.Interpret and calculate minimum design loads, fixture unit values, and pipe sizing criteria using IPC Chapter 7 and Chapter 10.
10.Identify the specific requirements for sanitary drainage systems, including cleanout placement, slope, and waste stack sizing.
11.Distinguish between the regulatory authority of the Administrative Authority (code official) and the responsibility of the Master Plumber regarding permits, inspections, and code compliance.
12.Recognize common exam traps related to code definitions, table footnotes, and specific exceptions that are frequently tested.
1.1 The Foundation: Code Structure and Administrative Authority
The 2018 IPC is a model code, but in Delaware, it is adopted with state-specific amendments. As a Master Plumber, you are responsible for knowing the adopted code, not just the model code. The exam is open-book, so your speed in finding answers is as critical as your knowledge.
Code Hierarchy: The IPC is organized into chapters, with the first several chapters being administrative and the remainder being technical. The IFGC is similarly structured. Chapter 1 of both codes is the Scope and Administration chapter. This is where you find the legal authority, permits, inspections, and the powers of the code official. Do not skip this chapter; it is a frequent source of exam questions regarding who is responsible for what.
The Code Official vs. The Master Plumber: The code official has the authority to interpret the code, approve alternative methods, and conduct inspections. However, the Master Plumber holds the license and is responsible for the work performed under that license. The code does not design the system; the plumber does. The code sets the minimum standard. A common trap is confusing the code official's right to waive a specific requirement (which they may do with approval) with the plumber's obligation to request that waiver in writing. Never assume a field deviation is acceptable without documented approval.
Permits and Inspections: The code requires a permit for the installation, alteration, or repair of a plumbing system. The Master Plumber is responsible for ensuring the permit is obtained. The code specifies that the permit holder must notify the code official when work is ready for inspection. The work must remain accessible until inspected. A key trap: Concealment of work before inspection is a violation, regardless of whether the work is correct.
1.2 Definitions and Abbreviations: The Language of the Code
Chapter 2 of the IPC and Chapter 2 of the IFGC contain definitions. In an open-book exam, you must know which chapter to open. Do not rely on memory for definitions; rely on your ability to find them.
Key Definitions to Master:
Air Gap (Drainage): The unobstructed vertical distance through the free atmosphere between the outlet of a waste pipe and the flood level rim of the receptor. This is a physical separation, not a device.
Air Gap (Water Distribution): The unobstructed vertical distance between the outlet of a potable water supply and the flood level rim of a tank or receptor. This is the highest level of backflow protection.
Backflow: The flow of water or other liquids, mixtures, or substances into the potable water system from any source other than the intended source.
Backsiphonage: Backflow caused by a negative pressure (vacuum) in the potable water system.
Fixture Unit (drainage - dfu): A unit of measure applied to the probable discharge of a fixture. It is not a volume, but a probability factor based on the rate of discharge and the duration of use.
Fixture Unit (water supply - wsfu): A unit of measure applied to the probable demand of a fixture. It is based on the flow rate and the duration of use.
Stack: A vertical main line of soil, waste, or vent piping.
Wet Vent: A vent that also receives the discharge of waste from other fixtures.
The Trap: The code defines a "Vent System" as a pipe or pipes installed to provide a flow of air to or from a drainage system. A common exam question will ask you to identify which pipe is not a vent, such as a cleanout or a floor drain, which are part of the drainage system, not the vent system.
1.3 General Regulations: Chapter 3
IPC Chapter 3 is the "catch-all" for general requirements. This is where you find the rules for:
Fixture Materials and Location: All fixtures must be smooth, non-absorbent, and corrosion-resistant. They must be accessible for cleaning and inspection. A trap: Fixtures must be connected to the drainage system, but every fixture must be individually trapped, except where a fixture has an integral trap (e.g., a water closet).
Protection of Pipes: Pipes must be protected from freezing, corrosion, and physical damage. This includes sleeving pipes through concrete or masonry walls.
Water Hammer: The code requires water hammer arrestors where quick-closing valves are installed. This is a design responsibility, not just an installation detail.
Cutting and Notching: This is a critical field point. The code specifies limits on cutting, notching, and boring of framing members. As a Master Plumber, you are responsible for ensuring that your rough-in does not compromise the structural integrity of the building. This is a common area of conflict with general contractors and a frequent exam topic.
1.4 Fixtures, Faucets, and Fixture Fittings: Chapter 4
This chapter covers the specific requirements for each type of fixture. You must know the minimum number of fixtures required for a given occupancy, which is found in IPC Table 403.1. This table is a must-know for design questions.
Key Concepts:
Water Closets: The maximum distance from a water closet to a wall or partition is 15 inches from the centerline to the wall, with a minimum of 15 inches of clear space in front. The minimum distance between water closets is 30 inches center-to-center.
Urinals: Urinals are not permitted to be used to satisfy the minimum number of water closets required for a building, except in specific occupancies (e.g., schools).
Lavatories and Sinks: Must be provided with hot and cold water. The code specifies the minimum flow rates for faucets to promote water conservation.
Floor Drains: Required in specific locations, such as public toilet rooms, laundry rooms, and mechanical rooms. A floor drain must be trapped and vented. A common trap: A floor drain in a mechanical room may not require a primer if it is not subject to evaporation, but in most commercial applications, a trap primer is required to maintain the seal.
1.5 Water Heaters: Chapter 5
This chapter is critical for both plumbing and fuel gas codes, as water heaters are a major point of intersection.
Key Requirements:
Location: Water heaters must be located so they are accessible for servicing. They must be protected from freezing.
Relief Valves: Every water heater must have a temperature and pressure (T&P) relief valve. The valve must be rated for the BTU/hour input of the heater. The discharge pipe must be piped to a safe point of disposal, with no valve in the line, and must be the same size as the valve outlet.
Pan and Drain: Where a water heater is installed in a location where leakage could cause damage, it must be installed in a pan with a drain.
Expansion Tanks: The code requires a thermal expansion control device (expansion tank) where a backflow prevention device (e.g., a check valve or pressure-reducing valve) is installed on the water supply. This is a frequent exam trap.
1.6 Water Supply and Distribution: Chapter 6
This chapter covers the design and installation of the potable water system.
Key Concepts:
Water Supply Sizing: The system must be sized using IPC Table 603.1 (water supply fixture units) and the Hunter's Curve concept. You must be able to calculate the total wsfu for a building and then use the appropriate table to determine pipe size based on the developed length and pressure.
Pressure Requirements: The minimum pressure at any fixture is 8 psi (55 kPa). The maximum static pressure is 80 psi (550 kPa). If the static pressure exceeds 80 psi, a pressure-reducing valve (PRV) is required.
Backflow Prevention: This is a major topic. The code requires protection against backflow at the point of the water service connection (e.g., a reduced pressure principle assembly) and at individual fixtures (e.g., air gaps, vacuum breakers). The type of protection is based on the degree of hazard.
Valves: The code specifies where shutoff valves are required. For example, each fixture must have an accessible shutoff valve, except for bathtubs and showers.
1.7 Sanitary Drainage: Chapter 7
This is the core of the plumbing code.
Key Concepts:
Drainage System Sizing: The system must be sized using IPC Table 710.1(1) and Table 710.1(2). These tables provide the maximum number of fixture units that can be connected to a pipe of a given size at a given slope.
Slope: Horizontal drainage pipes must be installed in uniform alignment at a slope of ¼ inch per foot (2% slope) for pipes 3 inches and smaller, and ⅛ inch per foot (1% slope) for pipes 4 inches and larger. This is a fundamental rule.
Cleanouts: Cleanouts are required at the base of each vertical stack, at the upper end of each horizontal branch, and at intervals not to exceed 100 feet in horizontal runs. The code specifies the minimum size of cleanouts.
Waste Stack vs. Soil Stack: A soil stack carries fecal matter; a waste stack carries liquid waste only. The sizing and venting requirements differ.
Building Drain vs. Building Sewer: The building drain is the lowest horizontal piping that receives the discharge from the stacks and conveys it to the building sewer. The building sewer begins at a point 3 feet (0.9 m) outside the foundation wall.
1.8 Vents: Chapter 9
The venting system is the most misunderstood and heavily tested area of the code. The purpose of venting is to protect trap seals from siphonage and backpressure.
Key Principles:
Vent Termination: Vents must terminate outdoors, not under the soffit or in an attic. The termination must be at least 6 inches above the roof, and at least 10 feet horizontally from a window or door opening.
Vent Sizing: The size of a vent is based on the size of the drain it serves and the total fixture units connected to that vent. IPC Table 910.2 is the primary sizing table.
Vent Types:
Individual Vent: A vent that serves a single fixture.
Common Vent: A vent that serves two fixtures on the same floor.
Wet Vent: A vent that also serves as a drain for a fixture. Wet venting is permitted for a specific combination of fixtures (e.g., a lavatory wet venting a water closet).
Circuit Vent: A vent that serves multiple fixtures on a horizontal branch, typically in a battery of fixtures.
The ½ Rule: A vent must be sized to handle the air flow required to prevent pressure fluctuations. A common rule is that the vent must be at least ½ the diameter of the drain it serves, but this is a simplification. The tables are the authority.
1.9 Traps: Chapter 10
Key Concepts:
Trap Seal: Every fixture must have a trap. The trap seal must be a minimum of 2 inches and a maximum of 4 inches. The water seal is the barrier against sewer gas.
Trap Size: The trap must be the same size as the fixture drain outlet.
Prohibited Traps: Traps that have moving parts, are not self-cleaning, or are of the "bell" type are prohibited.
Trap Priming: Traps that are subject to evaporation (e.g., floor drains in infrequently used areas) must be primed. This can be done with a trap primer device or by connecting the drain to a fixture that discharges frequently.
1.10 Fuel Gas: IFGC Fundamentals
The IFGC is a separate code, but a Master Plumber in Delaware is often responsible for gas piping.
Key Concepts:
Sizing Gas Piping: Gas piping is sized based on the BTU/hour load of the appliances, the length of the run, and the specific gravity of the gas. IFGC Table 402.4 is the standard sizing table for natural gas.
Pressure Drop: The code limits the pressure drop in a gas piping system. For low-pressure systems (less than 14 inches water column), the drop is typically 0.5 inches water column.
Piping Materials: The code specifies approved materials for gas piping, including black steel, copper (for specific gases), and CSST (corrugated stainless steel tubing).
Shutoff Valves: A shutoff valve is required at each appliance.
Sediment Traps: A sediment trap (drip leg) is required at the point of connection to an appliance.
Code Navigation: Where to Find It
Concept
Primary Location
Secondary Location
Administrative rules, permits, inspections
IPC Chapter 1
IFGC Chapter 1
Definitions
IPC Chapter 2
IFGC Chapter 2
General regulations (protection of pipes)
IPC Chapter 3
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Fixture requirements & minimum counts
IPC Chapter 4
IPC Table 403.1
Water heaters & relief valves
IPC Chapter 5
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Water supply sizing & backflow
IPC Chapter 6
IPC Table 603.1
Sanitary drainage sizing & slope
IPC Chapter 7
IPC Tables 710.1(1), 710.1(2)
Indirect wastes
IPC Chapter 8
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Venting requirements & sizing
IPC Chapter 9
IPC Table 910.2
Traps & interceptors
IPC Chapter 10
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Gas piping sizing & installation
IFGC Chapter 4
IFGC Table 402.4
Gas appliance venting
IFGC Chapter 5
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Practical Field Points for the Master Plumber
108.Coordination is Key: Before you cut a single pipe, coordinate with the structural, electrical, and HVAC trades. Your responsibility is to ensure your rough-in does not conflict with theirs.
109.Documentation: Keep a daily log of your work, including photos of the rough-in before concealment. This is your defense in a dispute.
110.Pressure Testing: The code requires a water or air test of the drainage and vent system. As the Master Plumber, you are responsible for performing this test in the presence of the inspector. Do not proceed to concealment until the test is witnessed and approved.
111.Know Your Local Amendments: Delaware may have state-specific amendments to the IPC. The exam is based on the adopted code, so be sure to study the Delaware amendments.
Common Exam Traps
The "Minimum" Trap: The code sets minimums, not maximums. A question might ask for the minimum slope for a 4-inch pipe (⅛ inch per foot), and a distractor will be ¼ inch per foot (which is the minimum for a 3-inch pipe).
The "Exception" Trap: Many code sections have exceptions. A question may state a general rule, and the correct answer is the exception. Always read the exceptions.
The "Definition" Trap: The code defines a "Vent" as a pipe that provides air circulation. A floor drain is not a vent, even if it is connected to the vent system.
The "Table Footnote" Trap: Tables often have footnotes that modify the values in the table. For example, the fixture unit value for a continuous flow fixture is calculated differently. Always read the footnotes.
The "Unit" Trap: Do not confuse drainage fixture units (dfu) with water supply fixture units (wsfu). They are different values and are used in different tables.
