Contractor's Guide to the Plumbing Code

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Explains the 2003 International Plumbing Code in plain English. Filled with illustrations and figures to help contractors meet code on all plumbing work. Covers history of the code, conventional DWV systems, cost factors that may affect plumbing design and much more.

Weight 0.7200
ISBN 1-58001-194-2
Page Count 95
Author David Cantrell and Robert G. Braun II
Publisher International Code Council
Dimensions 8-1/2 x 11

This new publication by ICBO explains the 2003 International Plumbing Code in plain English. It's filled with illustrations and figures to help contractors meet code on all plumbing work. Covers history of the code, conventional DWV systems, cost factors that may affect plumbing design and much more.

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Table of Contents
1 Plumbing Codes-Who Needs Them?, 1

Background, 1
Administrative Details, 10

2 Definitions, 13

Overview, 13
3 Documentation, Standards, Alternatives and Inspections, 29

General, 29
Getting the Permit, 29
Documentation, 30
The Code Official, 32
Standards and Approvals, 32
Materials, Plans and Preliminary Layout, 34
Required Inspections, 39

4 Conventional Drain, Waste and Vent Systems, 41

Typical Schematic, 42
Drainline Connections, 43
Sizing the Drainage System, 45
Cleanouts, 47
Venting, 47
Vent Termination, 48
Nonconventional Venting Methods, 51
Indirect Drains and Special wastes, 59
Installing the Pipe and Fittings, 60

5 Water Supply and Distribution, 63

Water Is a Good Thing, 63
Water Services, 63
Sizing Those Pipes, 64
Water Hammer, 66
Is Cheap Pipe the Best Way?, 69
The Installation, 69
Too Hot for Me...Hot Water, 69
Back flow Devices, 69
Healthcare Plumbing, 70

6 Fixtures that Use Water, 75

Fixtures, 75
Number of Fixtures, 76
Other Fixtures, 77
Dishwashers and Showers, 78
Water Heaters [C-B], 78

7 Storm Drainage, 83

General, 83
Materials, 83
Roof Drain and Overflow Design, 84
Specific Design Criteria and Details, 85
Scuppers and Leaders, 86
Combined Storm and Sewer Systems, 87
Below-grade Storm Drain Systems, 87
Engineer-designed Systems, 88

8 Private Disposal Systems, 89

General, 89

Index, 91

Plumbing Codes-Who Needs Them?

In this chapter, we will discuss the importance of plumbing, the history of how it has evolved over the years, the reasons for codes, the purposes of codes, how codes are produced and the origin of the technical code provisions in the United States. The role of the building department in enforcing codes and reasons for permits are also discussed.


Ah, the comforts of home, a nice beautiful home! You've been able to build your dream home, and now you can enjoy the remainder of your days. Except that you've just discovered a couple of glitches. The toilet doesn't always flush, and you keep calling the plumber to come out and snake the lines. And why do you get those terrible smells in your house?

These are just some of the problems that can occur if the plumbing is not installed correctly. That is why a well-working plumbing system is dependent on good design and the installation practices of those who have acquired the necessary technical knowledge and skills.

But that doesn't necessarily mean that you have to be a plumber to accomplish this task. There are technical guides and other books that can help you and can teach you what to do. Modern, up-to-date plumbing codes are designed to provide minimum requirements for installation so that we can have a lasting product that will bring us happiness and pleasure for many years.

Some History
When did plumbing originate? It may surprise you to discover that plumbing has been around in one form or another throughout much of recorded history. Written evidence has been traced as far back as Biblical times in Mesopotamian cities, particularly in Babylon, under King Hammurabi (see Figure 1-1)(O'Bannon 1989).

In fact, some earthenware pipes, masonry sewers and toilets installed by the Mesopotamians in about the years 2500 BC are still in fair work order. The members of the ancient nation of Israel were in their laws to go outside the camp along with a digging instrument to "take care of business," burying the evidence, so to speak. (Deuteronomy 23:13.)

This was obviously a healthy practice. Disease was less likely to spread in their community. This, along with other public health practices such as washing one's hands afterwards, has proven to be one of the most effective methods of containing the spread of disease.

Later, the ancient Romans did much to develop systems for supplying clean water. Unfortunately, they also used lead piping, which probably inadvertently poisoned the populace and may have been one of the factors leading to the downfall of the Roman Empire. Even though such sanitary practices broke down in Europe during medieval and renaissance times, the need for these basic concepts is unchanged today.

During the 17th century, many cities began to construct water and sewer systems, and in 1793 a cholera epidemic struck Philadelphia, Pennsylvania, stimulating the construction of the first major water system in the United States.

Plumbing Codes
So, no matter how much shelter and comfort that beautifully constructed home of yours provides, you and your family are still highly dependent on the plumbing system. This is where a modern family of building regulations, such as the set that includes the International Plumbing Code (IPC) and the International Private Sewage Disposal Code (IPSDC), is essential in the design of acceptable sanitary systems. If the plumbing in a building isn't working correctly, it is unlikely that you're going to want to live there. The minimum provisions for plumbing systems result in an end product that will bring years of enjoyable and comfortable living.

Many of us have no intention of doing our own plumbing. We would rather enlist the services of a professional. Nonetheless, having a better understanding of the basic concepts of plumbing as outlined in the IPC will no doubt assist us in our understanding of what is being done and help us better communicate our needs and concerns to the plumber.

Where Did Modern Plumbing Codes and Their Requirements Come from Anyway?
The International Pluming Code: A Guide for Use and Adoption (ICC, 1998) provides a very helpful overview of the technical basis of the IPC. Here are some highlights from its first chapter:

The IPC was the first code developed with the full cooperation of the three model code groups: Building Officials and Code Administrators International, Inc. (BOCA), International Conference of Building Officials (ICBO), and Southern Building Code Congress International, Inc. (SBCCI). The intent was to regulate plumbing with the most technically accurate code. The original intent of the IPC was to recognize all acceptable methods for the various plumbing systems. The code did not attempt to arbitrarily restrict any method, material, concept or system. Since its initial development, the IPC has been and will continue to be updated through a code change process with participation from nationally recognized industry experts.

Development of the Code
The IPC was developed through a cooperative effort of BOCA, ICBO and SBCCI (see Figure 1-2). The first draft of the IPC was prepared by a select group of plumbing officials working with the staff of the three organizations. This committee reviewed the contents of the BOCA National Plumbing Code, the ICBO Plumbing Code and the SBCCI Standard Plumbing Code.

A draft of the code was prepared for review by the industry. The first draft contained only excerpts from the three plumbing codes, with no new concepts or ideas added. All of the allowable practices were already permitted and used by one of the model plumbing codes. The premise was that the code should have its origins based on the content of the existing plumbing codes.

It was recognized that no one part of the United states had used all of the plumbing practices that would be permitted in the new plumbing code. Terminology would also be an initial difficulty insofar as different parts of the country use the same name to describe different plumbing systems.

When the draft was issued, it was subject to a review process through a series of public hearings. A committee of plumbing officials was appointed to consider all of the testimony on the first draft. The hearings were well attended by plumbing experts from all areas of the industry. New provisions were proposed for inclusion at the hearing, including a complete rewrite of the backflow section. The new requirements received overwhelming support at the public hearings.

After modifying the draft to include the acceptable changes based on the testimony at the public hearings, the document was forwarded to the membership of BOCA, ICBO and SBCCI. The three organizations voted unanimously to accept the new code as a replacement document for their organizations' plumbing codes. In 1995, the International Code Council, Inc. published the first edition of the IPC.

Recognition of New Technology
The original committee that drafted the IPC developed a philosophy based on acceptance of new technology, including new materials and products, as well as new methods of installation.

Although the acceptance of new technology is paramount to the IPC, any new idea, concept or material must be substantiated with technical documentation and reviewed through the open code change process.

Code Change Process
The IPC has an 18 month code change cycle for the review of all new proposals, which is open and available to everyone. The ICC accepts code change proposals submitted before the deadline date, with no limitations placed on the submittal of code changes. Every code change is reviewed by the staffs of the three model code groups to address any administrative concerns. This provides every proponent of a code change with the best opportunity of being considered favorably.

The code changes are published in a document for distribution to any interested party. A public hearing is scheduled for discussion by the proponents and opponents of each code change. The hearings are conducted before the ICC Plumbing Code Change Committee, a select group of plumbing professionals. The committee Is made up of plumbing inspectors, plumbing engineers, labor representatives and representatives of testing laboratories.

After hearing public testimony, the committee votes to recommend either approval, approval with modifications or disapproval of the code change. The results of the action taken by the committee are published with reasons for every action taken.

The recommendations of the committee can be challenged during the second series of public hearings, where any challenged code change is open for discussion. The vote at the second hearing is by the designated voting membership of ICC, which are those individuals appointed by ICC member jurisdictions. Each member jurisdiction is allowed a minimum number of votes based on their population. The membership can either agree or disagree with the committee's recommendation. A two- thirds majority of those voting is required to overturn the committee's recommendation and approve a code change.

The approved code changes are published in the supplement to, or the new edition of, the IPC.

Administration and Enforcement
Chapter I of the IPC follows the guidelines established by the legal community for the regulation of construction codes. The IPC is consistent with the recommendations of Legal Aspects of Code Administration The administration requirements in the IPC recognize that, once adopted by a jurisdiction, the code becomes a legal document. The administration and enforcement become the responsibility of the local jurisdiction. This is the philosophy regarding the adoption of any model code. Note that the appedices found in the IPC must be specifically adopted by the jurisdiction in order to be applicable.

Alternative Approval
Section 105 of the IPC includes the requirements for alternative approval. This section, often considered the most powerful section of the code, follows the guidelines of the Federal Trade Commission for permitting the acceptance of new technology. It permits the code official to accept any alternative material, method or equipment that may not be recognized directly in the code.

The IPC is unique in specifying the requirements for alternative engineered design in the approval section. These provisions are consistent with the various state engineering and architectural registration acts. A registered design professional is permitted to design any plumbing system, provided that he or she has adequate technical documentation and testing to justify the alternative design. The alternative engineered design section was originally developed by Bernie McCarty, P.E., past president of the American Society of Plumbing Engineers (ASPE). McCarty submitted the code text on behalf of ASPE, in support to the Society's position regarding engineering design.

Consistent with Federal Guidelines
The IPC was developed consistent with federal guidelines regarding seismic protection and floodproofing. The seismic requirements in the IPC are consistent with the recommendations of the National Earthquake Hazards Reduction Program (NEHRP). The IPC references the building code in Section 308.2 for specific regulations relating to the location of the building.

The floodproofing requirements in the IPC were developed through a contract with the Federal Emergency Management Agency. Floodproofing requirements are contained in Section 309 of the IPC and in the International Building Code.

Referenced Standards
The IPC relies on references to nationally developed consensus standards. To assist the code user, the IPC directly references the appropriate standard throughout the body of the code. The complete list of the referenced standards appears in Chapter 13, listed in order of the promulgating organization.

The ICC developed a criterion for the acceptance of referenced standards. To ensure fairness, the standards are required to be developed by the consensus process.

The standards are also required to be written in mandatory language without permissive or subjective text, allowing the standard to be a legally enforceable document. If there is any permissive text in a standard, it raises the issue of enforceability and who will make the decision regarding the permissive requirement. All standards are reviewed for adherence to the ICC policy.

What follows is a summary of where the technical provisions of the IPC originated.

International Residential Code (IRC)
The IPC is generally not intended for the regulation of plumbing systems in single-family dwellings and other small residential structures. The International Residential Code (IRC) was developed to address such work. The scope of the IRC includes one-family dwellings, two-family dwellings, multiple one-family dwelllings (referred to as townhouses), and all of their accessory structures. The IRC has its own set of plumbing requirements applicable only to this group of residential occupancies. Most jurisdictions adopt both the IRC and IPC, with each code regulating a specific type of buildings. Where the IRC has been adopted, the IPC is not used for the above-mentioned residential uses; however, many of the requirements are consistent in both codes.

Fixture Requirements
Minimum Number of Fixtures Required-
The IPC specifies the minimum number of plumbing fixtures required for every building occupancy, based on both the number of building occupants and the occupancy classification and use group. The occupant load used for the purpose of determining the minimum number of plumbing fixtures is typically the same as that used for the design of the editing system. This procedure is established in Section 1004 of the International Building Code (IBC). However, there are times where the code official may consider a different number of occupants for fixture count purposes than that used for emitting, but only where it can be shown that a more representative occupant load is appropriate.

Potty Parity-Around 1980, it was recognized that plumbing codes were providing an injustice to the female population by requiring an inordinate amount of plumbing fixtures for the male population. The inequity resulted from plumbing codes specifying a minimum number of water closets, as well as a minimum number of urinals, for the male population. It was also recognized that the waiting period for the female population far exceeded any waiting time incurred by the male population. Studies were performed by Dr. Sandra Rawls at the University of Virginia, Stevens Institute of Technology, the National Restaurant Association and the ASPE Research Foundations. The results of these studies are reflected in the IPC.

In developing code requirements for assembly buildings, the studies used the waiting time required. Hence, the urination process was analyzed for determining the minimum number of fixtures. If the female population requires twice as long to complete the urination process, they would need twice as many fixtures to have the same waiting period as the male population. Thus the code reflects the requirements for twice as many water closets in the ladies' room when compared to the men's room.

Studies by the National Restaurant Association indicated that "potty parity" was not required for restaurants or nightclubs. As a result, the average time factor for fixture use (rather than waiting time) can be applied, resulting in an equal distribution of of plumbing fixtures.

To prevent the inequality of fixtures from occuring the requirement for a urinal to be mandatory fixture was removed from the code.This was also necessary for smaller toilet rooms that were designed for one fixture. The urinal is now permitted to be substituted for a maximum of 67 percent of the required number of water closets.

Plumbing Fixtures-The IPC directly references the International Building Code, which regulates accessible plumbing fixture requirements and identifies the accessibility for various buildings in Chapter 11.

Installation of Fixtures-The IPC regulates the to provide both comfort and social privacy. The spacing requirements are based on the results of a study conducted at Cornell University, published in a book entitled The Bathroom. Alexander Kira headed a study that completely analyzed the use of the various plumbing fixtures. The study concluded that adequate spacing was required between fixtures in public toilet rooms to help facilitate their use and to avoid direct body contact between users of fixtures.

The minimum spacing for urinals of 30 inches reflects a dimension that will eliminate direct contact with the user of the adjacent fixture.

The study at Cornell was also used to determine the minimum size of a shower to accommodate movement of the individual to allow for the cleansing of the lower extremities.

Individual Fixture Requirements: An example would be the backflow requirements for fixtures and appliances. Section 406.2 requires an automatic clothes washer to have an integral air gap built into the machine, or the water supply must be protected against backflow in accordance with the requirements of Section 608. Although residential and coinoperated automatic clothes washers have integral air gaps, this is not true for many large commercial machines. For these larger machines, backflow protection is provided on the water supply to the appliance. The backflow requirements are also similar for dishwashers. The IPC is complete in specifying regulations for both residential and commercial appliances and fixtures. It is important to note that where the International Residential Code (IRC) is adopted by the jurisdiction, the IRC contains all of the plumbing code requirements that apply to single-family dwellings, two-family dwellings and townhouses.

Water Piping Systems Piping Material: The acceptable piping materials for water service and water distribution systems are listed in Tables 605.4 and 605.5. The IPC accepts all the common water piping materials, such as copper tubing, CPVC, galvanized steel, cross-linked polyethylene and PEX-AL-PEX. There are no arbitrary restrictions or prohibitions placed on the installation of any water piping materials. The tables identify the acceptable materials by reference to the ASTM or CSA standards. The IPC relies on these organizations for the development of acceptable material standards. Each standard is reviewed for completeness and compliance with the ICC standards policy.

Design Criteria for Sizing-Table 604.3 of the IPC specifies the minimum criteria for the design of a water distribution system but is often misunderstood to be the minimum flow rates required for the specified plumbing fixtures. However, the criteria are used only for purposes of sizing a water distribution system. The values for flow rates and minimum pressures are used independent of one another. The flow rate values are used in determining the peak demand of the system, and the pressure values are the minimum requirements for the most demanding fixture operating under a peak demand condition. The flow rates are similar to the values published in the ASPE Data Book and are consistent with the fixture requirements specified in ANSI/ASME A112.18.1 and ANSI/ASME A112.19.6.

Maximum Flow Rates-The federal government imposed mandatory requirements for plumbing fixtures as part of the legislation for water and energy conservation. The IPC maintains consistency with the federal legislation by specifying the maximum flow rates (at specified pressures) that are the same as the federal legislation.

Minimum Pipe Size-Table 604.5 specifies the minimum water-pipe size required on the supply to each fixture. The minimum pipe sizes specified are consistent with those specified in the ASPE Data Book.

System Sizing Requirements-The IPC requires the water distribution system to be designed in accordance with accepted engineering practices. This provides the system designer with the flexibility to use any approved sizing method. The IPC permits the plumbing engineer to evaluate each water distribution system for peak demand and size the system accordingly. Plumbing engineers and system designers have been employing computer programs to size water distribution systems more accurately.

Many of the water-pipe sizing procedures use the concept of supply fixture units to determine the minimum pipe size. This method was originally developed by Dr. Roy B. Hunter, who wrote in BMS 799, "The design layout and the selection of material and pipe layout and the selection of material and pipe [should be] delegated to an engineer experienced in this fleld." The ASPE Research Foundation called for the abandonment of supply fixture-unit sizing methods in a report to the plumbing engineering community and considers the fixture-unit sizing method to be out of date for sizing water-distribution systems, however, it is still considered to be an acceptable method for determining the mini-mum sizing for code compliance.

Although the IPC does not mandate a method that must be followed for sizing a water-distribution system, two methods of sizing are provided in Appendix E. These methods follow the precepts of Hunter's original water-pipe sizing procedure. Appendix E is provided for assistance to the code user, especially for smaller buildings that are designed by plumbing contractors. The use of Appendix E is not mandated by the code but rather provides two different procedures for sizing a water piping system. The appendix acts more as a guideline for pipe sizing, rather than a required method. Other sizing or design methods are also acceptable when they conform to good engineering practice standards and are approved by the code official.

Water Hammer-The plumbing community has recognized that water hammer in a piping system can only be controlled by prevention or with the installation of water-hammer arresters. Julius Ballanco, P.E., reported that controlling velocity to prevent water hammer was dependent on the type of water piping material installed. Section 604.9 of the IPC follows the engineering guidelines for water-hammer control. Both Ballanco and Steele reported that air chambers are ineffective in controlling water hammer. Both individuals reported that the only viable method for preventing the occurrence of water hammer was the installation of water-hammer arresters or by controlling the velocity of flow in the piping.

Backflow Protection-Backflow protection is considered the most important aspect of a plumbing code. The backflow protection requirements in the IPC have been developed with the input of the leading backflow protection experts in the country using the latest information and references to national consensus standards.

Air Gap-The most common method of protecting the potable water supply is with an air gap. The minimum air-gap requirements are consistent with the air-gap requirements specified in ANSI/ASME A112.1.2 that were developed in 1942. They have been the mainstay of the plumbing industry for air-gap requirements.

Maintenance of Hot Water-In large buildings, the design professional will often design a water distribution system with long runs of piping for the hot water. Where the developed length of hot water piping exceeds 100 feet, the supply system must be provided with a method of maintaining the temperature in accordance with the International Energy Conservation Code (IECC). The methods of maintaining the water temperature are recirculation systems or temperature maintenance systems such as "heat trace" (also referred to as "heat tape" or "pipe heating cable"). For these systems the IECC requires the pipe to be insulated with insulation not exceeding .27 Btu per inch/h•Ft2•F.

Although not specifically stated in the IECC, those systems with long runs that are heated with "heat trace" are also intended to be insulated unless their listing or manufacturer's installation instructions state otherwise.

In addition, water-heating equipment not supplied with integral heat traps and serving noncirculating systems, and not heated by heat trace, are to be provided with heat traps on the supply and discharge piping of the heating equipment. The first 8 feet of supply and discharge piping is to be insulated the same as required for systems with long runs.

The IPC requires all water heaters to have pressure and temperature relief protection.

Background and Overview of the 2003 International Plumbing Code

A valuable tool to help understand the 2003 IPC!

This publication steps away from the legalese of codes and explains code provisions in a less formidable manner. This helpful guide helps contractors get up to speed quickly on the latest code provisions.

It contains numerous illustrations and figures as well as a unique section on key plumbing terms and definitions.

Chapters include:

  • History of plumbing codes
  • Discussions of conventional DWV systems
  • Water supply and distribution
  • And much more!

Contractor's Guide to the Plumbing Code is an excellent reference for plumbing/mechanical contractors, students and first-time code users.