General Regulations

General Regulations

The general regulations are the part of the 2024 International Plumbing Code (IPC 2024) that applies before any particular system is considered. They fall in two places: the administration of the code — scope, applicability, the powers of the code official, permits, construction documents, inspections, appeals and violations — and the chapter of general regulations, whose scope is the installation of plumbing not specific to another chapter, a general requirement being superseded by a more specific one where the two meet (IPC 2024, 301.1). This text is written from the printed lines of both, and every rule names the address it was read from. Where a printed line states no value — and one of them does not — no value is stated here.

1. Scope, purpose and what the code does not cover

The code is titled for the jurisdiction that adopts it and is referred to as this code (IPC 2024, 101.1). Its scope covers the erection, installation, alteration, repair, relocation, replacement, addition to, use and maintenance of plumbing systems in the jurisdiction, and it also regulates nonflammable medical gas, inhalation anesthetic, vacuum piping, nonmedical oxygen systems, and sanitary and condensate vacuum collection systems (IPC 2024, 101.2). The same printed section places fuel gas distribution piping and equipment, fuel gas-fired water heaters and water heater venting systems outside that scope, under the International Fuel Gas Code (IPC 2024, 101.2). Detached one- and two-family dwellings and townhouses of not more than three stories above grade plane with a separate means of egress, and their accessory structures, may comply with this code or with the International Residential Code (IPC 2024, 101.2). Provisions printed in the appendices do not apply unless specifically adopted (IPC 2024, 101.2.1). The purpose of the code is to establish minimum requirements for a reasonable level of safety, health, property protection and general welfare by regulating and controlling the design, construction, installation, quality of materials, location, operation and maintenance or use of plumbing equipment and systems (IPC 2024, 101.3), and if any section, subsection, sentence, clause or phrase is held unconstitutional the rest of the code is unaffected (IPC 2024, 101.4).

2. Applicability

Five rules decide which requirement wins. Where a general requirement conflicts with a specific one, the specific governs; where different sections specify different materials, methods of construction or other requirements for a specific case, the most restrictive governs (IPC 2024, 102.1). A plumbing system lawfully in existence when the code was adopted may continue to be used and maintained if that use, maintenance or repair follows the original design and creates no hazard to life, health or property (IPC 2024, 102.2), while work relating to building or structural issues is regulated by the International Existing Building Code (IPC 2024, 102.2.1). Existing and new systems, materials and appurtenances are maintained in proper operating condition in accordance with the original design, in a safe and sanitary condition, and any device or safeguard the code requires is maintained in compliance with the edition under which it was installed; the owner or the owner's authorized agent carries that responsibility, and the official may require any system to be reinspected (IPC 2024, 102.3). Additions, alterations, renovations and repairs meet what a new system would need, without forcing the existing system to satisfy every requirement, and must not leave an existing system unsafe, unsanitary or overloaded, minor work meeting the provisions for new construction unless it is done in the same manner and arrangement as the existing system, is not hazardous, and is approved (IPC 2024, 102.4). A change of occupancy that brings a structure under a special provision applicable to the new occupancy is unlawful without the official's approval, the official certifying that the structure meets the intent of the law governing building construction for that occupancy and that the change creates no hazard (IPC 2024, 102.5).

The provisions on construction, alteration, repair, enlargement, restoration, relocation or moving are not mandatory for buildings classified as historic, where the official judges them safe and in the public interest of health, safety and welfare for the proposed work (IPC 2024, 102.6). A plumbing system forming part of a building moved into or within the jurisdiction complies as a new installation, except as Section 102.2 determines (IPC 2024, 102.7), and no provision of the code nullifies a local, state or federal law (IPC 2024, 102.10). The codes and standards listed in the chapter of referenced standards are part of the code's requirements to the prescribed extent of each reference (IPC 2024, 102.8); where this code and a referenced standard conflict, this code applies (IPC 2024, 102.8.1); where the referenced document reaches subject matter within the scope of this code, this code takes precedence (IPC 2024, 102.8.2). A requirement needed for the strength, stability or proper operation of a system, or for public safety, health and general welfare, that the code does not cover specifically is determined by the code official (IPC 2024, 102.9), and a reference to chapter and section numbers, or to provisions not identified by number, is construed as a reference to that chapter, section or provision (IPC 2024, 102.11).

3. The code official

The agency charged with implementation, administration and enforcement is created by the code, and its head is the code official (IPC 2024, 103.1), appointed by the chief appointing authority of the jurisdiction (IPC 2024, 103.2) and authorised to appoint a deputy code official and other officers, inspectors and employees holding the powers delegated to them (IPC 2024, 103.3). The official is directed to enforce the provisions of the code (IPC 2024, 104.1).

The official determines compliance, renders interpretations, and adopts policies and procedures clarifying the code's application; those policies must comply with the intent and purpose of the code and must not waive a requirement the code specifically provides (IPC 2024, 104.2). Where a listing is required and a listing standard is named, the listing is based on that standard; where none is named, it rests on approved listing criteria. A listing is germane to the provision requiring it, installation follows the listing and the manufacturer's instructions, and both are made available to the official when compliance must be verified (IPC 2024, 104.2.1).

To determine compliance the official may require a technical opinion and report (IPC 2024, 104.2.2), provided without charge to the jurisdiction (IPC 2024, 104.2.2.1) and prepared by a qualified engineer, specialist, laboratory or specialty organization acceptable to the official (IPC 2024, 104.2.2.2), its content being an analysis of the design, operation or use of the building and of the facilities on it (IPC 2024, 104.2.2.3); where evidence of compliance is insufficient the official may require tests as evidence, by a party acceptable to the official, using the methods of the code or of another recognized standard (IPC 2024, 104.2.2.4). The code does not prevent the use of any material or the adoption of any design or method of construction it does not specifically prescribe, provided the alternative is not specifically prohibited and has been approved (IPC 2024, 104.2.3), approval being given where the official finds the alternative satisfactory (IPC 2024, 104.2.3.1) and at least equivalent to what the code prescribes as to quality, strength, effectiveness, durability, safety other than fire safety, and fire safety (IPC 2024, 104.2.3.4). Where carrying out the code involves practical difficulties, the official may grant a modification for an individual case after finding that a special individual reason makes the strict letter of the code impractical, that the modification complies with its intent and purpose, and that it does not reduce health, accessibility, life and fire safety or structural requirements (IPC 2024, 104.2.4); modifications in flood hazard areas are restricted to the grounds the section prints (IPC 2024, 104.2.4.1).

The official receives applications, reviews construction documents, issues permits, inspects the premises for which permits have been issued, and enforces compliance (IPC 2024, 104.3), determining in flood hazard areas whether the proposed work is substantial improvement or repair of substantial damage and requiring the building to meet the flood provisions of the International Building Code or the International Residential Code where it is (IPC 2024, 104.3.1). Where an inspection is needed to enforce the code, or reasonable cause exists to believe a condition on the premises is contrary to it and makes the premises unsafe, dangerous or hazardous, the official may enter at reasonable times; on an occupied structure the official presents credentials and requests entry, on an unoccupied one a reasonable effort is made to find the owner, the owner's authorized agent or the person in charge, and if entry is refused the official has recourse to every remedy provided by law (IPC 2024, 104.4). Once a proper inspection warrant or other legal remedy has been obtained, an owner, agent, occupant or person in charge must not fail or neglect to permit entry for inspection and examination (IPC 2024, 104.4.1). The official carries proper identification while inspecting (IPC 2024, 104.5) and issues the notices or orders needed to ensure compliance, notices of violation following Section 114 (IPC 2024, 104.6).

The official keeps official records as Sections 104.7.1 through 104.7.5 require, retained for at least 5 years or for as long as the building they relate to exists (IPC 2024, 104.7), covering approvals open to public inspection during business hours (IPC 2024, 104.7.1), each inspection with its findings and disposition (IPC 2024, 104.7.2), the written applications and final decisions on alternatives and on modifications (IPC 2024, 104.7.3), the tests conducted to comply with Sections 104.2.2.4 and 104.2.3.5 (IPC 2024, 104.7.4) and fees collected and refunded (IPC 2024, 104.7.5). The official, a member of the board of appeals, or an employee charged with enforcement, acting in good faith and without malice, is not personally liable civilly or criminally for any act or omission in the discharge of those duties (IPC 2024, 104.8), and a suit or criminal complaint for an act performed in their lawful discharge is defended by the jurisdiction's legal representative (IPC 2024, 104.8.1). Approved materials, equipment and devices are constructed and installed in accordance with that approval (IPC 2024, 104.9) and are not reused unless they are in good working condition and approved (IPC 2024, 104.9.1).

4. Permits

An owner, an owner's authorized agent or a contractor who intends to construct, enlarge, alter, repair, move, demolish or change the occupancy of a building, or to erect, install, enlarge, alter, repair, remove, convert or replace a plumbing system regulated by the code, or to cause that work to be done, first applies to the code official and obtains the required permit (IPC 2024, 105.1). In place of a permit for each alteration to an already approved system, equipment or appliance installation, the official may issue an annual permit to a person, firm or corporation that regularly employs one or more qualified tradespersons in the building or premises concerned (IPC 2024, 105.1.1), the holder keeping a detailed record of the alterations made under it, accessible to the official at all times or filed as the official designates (IPC 2024, 105.1.2).

Two kinds of work are exempt. Stopping leaks in a drain, water, soil, waste or vent pipe is exempt, but if a concealed trap, drainpipe, water, soil, waste or vent pipe becomes defective and must be removed and replaced with new material, that work is new work, requiring a permit and an inspection (IPC 2024, 105.2). Clearing stoppages or repairing leaks in pipes, valves or fixtures, and removing and reinstalling water closets, are exempt provided the repairs do not involve or require replacing or rearranging valves, pipes or fixtures; the exemption does not authorise work done in violation of the code or of any other law or ordinance (IPC 2024, 105.2).

The application, with the required fee, is filed on the form the official furnishes, containing a general description of the proposed work and its location, signed by the owner or the owner's authorized agent, indicating the proposed occupancy of all parts of the building and of the portion of the site or lot not covered by a building, with the other information the official requires (IPC 2024, 105.3). Before the permit issues, the official may inspect and evaluate the systems, equipment, buildings, devices, premises and spaces to be used (IPC 2024, 105.3.1). An application is deemed abandoned 180 days after filing unless pursued in good faith or a permit has been issued, and the official may grant extensions of up to 180 days each, requested in writing with justifiable cause shown (IPC 2024, 105.3.2). The application is made by the person or agent who is to install all or part of the plumbing system, who must meet the qualifications established by statute, by rules promulgated by the code, or by ordinance or resolution, with full name and address stated (IPC 2024, 105.4). The application, the construction documents and the other data filed are reviewed by the official, and where the work conforms to the code and to the applicable laws and the fees of Section 108.1 have been paid, a permit issues (IPC 2024, 105.5). Where construction documents are required, they are endorsed and stamped "APPROVED", are not changed without the official's authorization, and the work is done in accordance with them; the official may permit construction of part of a system before the entire set of documents has been submitted or approved, provided adequate information and detailed statements have been filed, holders of such a permit proceeding at their own risk (IPC 2024, 105.5.1).

The permit carries conditions. Its issuance or the approval of documents is not a permit for, or an approval of, any violation, and a permit purporting to authorise a violation or to cancel a provision of the code is not valid (IPC 2024, 105.5.2). It expires and becomes null and void if the work does not commence within 180 days, or is suspended or abandoned for 180 days after it commenced; before the work restarts a new permit is obtained, at half the fee for a new permit, provided the construction documents have not changed and the suspension or abandonment has not exceeded one year (IPC 2024, 105.5.3). The holder of an unexpired permit may apply for an extension of the time to commence work for good and satisfactory reasons, and the official extends the time by up to 180 days where there is reasonable cause; a permit is extended only once, and the extension fee is half the fee for a new permit (IPC 2024, 105.5.4). The official may suspend or revoke a permit issued in error, on incorrect, inaccurate or incomplete information, or in violation of any ordinance, regulation or provision of the code (IPC 2024, 105.5.5), and the permit, or a copy, is kept on the site until the project is complete (IPC 2024, 105.5.7).

5. Construction documents

Construction documents, engineering calculations, diagrams and similar data are submitted in two or more sets, or in a digital format where the official allows it, with each application for a permit (IPC 2024, 106.1). The official requires them, with computations and specifications, to be prepared and designed by a registered design professional where state law requires it, and they are drawn to scale and clear enough to indicate the location, nature and extent of the proposed work and to show in detail that the work conforms to the code; for buildings more than two stories in height they indicate where penetrations will be made for pipes, fittings and components, and the materials and methods for maintaining required structural safety, fire-resistance rating and fireblocking (IPC 2024, 106.1). The official may waive the submission where the nature of the work makes reviewing it unnecessary to determine compliance (IPC 2024, 106.1). One set of approved documents is retained by the official for at least 180 days from completion of the permitted work, or as state or local law requires, and one set is returned to the applicant and kept on the site while the work is in progress (IPC 2024, 106.2).

6. Inspection and approval

After the prescribed tests and inspections show that the work complies in all respects, the official issues a notice of approval (IPC 2024, 107.1), and may suspend or revoke it in writing where it was issued in error, on incorrect information supplied, or where the building, premises or portion violates an ordinance, regulation or provision of the code (IPC 2024, 107.1.1). The official conducts the inspections needed to determine compliance, and work requiring a permit remains visible and accessible until approved; approval after an inspection is not an approval of a violation, and an inspection purporting to authorise a violation or cancel a requirement is not valid (IPC 2024, 111.1). The duty to keep the work visible and accessible is on the permit applicant, and neither the official nor the jurisdiction is liable for the cost of removing or replacing material to allow inspection (IPC 2024, 111.1).

On notification from the permit holder or the holder's agent, the official makes three inspections and either releases that portion of the construction or notifies the holder of violations to be corrected, scheduling being the holder's responsibility (IPC 2024, 111.2). An underground inspection comes after trenches or ditches are excavated and bedded and the piping installed, and before any backfill is placed. A rough-in inspection comes after the roof, framing, fireblocking, firestopping, draftstopping and bracing are in place and all sanitary, storm and water distribution piping is roughed in, and before wall or ceiling membranes are installed. A final inspection comes after the building is complete, all plumbing fixtures are in place and properly connected, and the structure is ready for occupancy (IPC 2024, 111.2). Beyond those three, the official may make or require other inspections to ascertain compliance with the code and other enforced laws (IPC 2024, 111.2.1), the permit holder or an authorized agent notifying the official when work is ready and providing access and the means for the required inspections (IPC 2024, 111.2.2). Work must not proceed beyond the point indicated in each successive inspection without the official's approval first; the official either indicates the portion satisfactory as completed or notifies the holder where it fails to comply, and a portion that does not comply is corrected and is not covered or concealed until the official authorises it (IPC 2024, 111.2.3). The official may accept reports from approved inspection agencies that satisfy the requirements as to qualifications and reliability (IPC 2024, 111.2.4).

Closed, prefabricated plumbing systems follow their own path: before such a system is approved and a permit issued, the official requires an evaluation report on the complete details of the system, including its components, the basis of evaluation and test results (IPC 2024, 111.2.5), designates an approved agency as the evaluation agency and reviews its report (IPC 2024, 111.2.5.1), and conducts in-plant inspections at the frequency needed to ensure conformance unless every part can be inspected at the site without dismantling, the system carrying a permanent identifying label showing that factory inspections have been performed (IPC 2024, 111.2.5.2), with test and inspection records available at all times during fabrication and erection (IPC 2024, 111.2.5.3).

An alternative engineered design is specially inspected: the registered design professional or a designated inspector periodically inspects and observes the installation to determine that it accords with the approved construction documents, brings discrepancies immediately to the plumbing contractor for correction, and keeps records of every inspection (IPC 2024, 111.3.1), and submits a final written report certifying conformance to those documents, no notice of approval issuing until that certification has been submitted (IPC 2024, 111.3.2). Plumbing work and systems are otherwise tested as Section 312 requires, with the permit holder making the tests and the official observing them (IPC 2024, 111.4). New systems, and parts of existing systems that have been altered, extended or repaired, are tested to disclose leaks and defects, except where the work does not include adding to, replacing, altering or relocating water supply, drainage or vent piping, and except plumbing equipment set up temporarily for exhibition purposes (IPC 2024, 111.4.1), the equipment, material and labour being furnished by the permit holder (IPC 2024, 111.4.2), and work that fails an initial test being corrected and resubmitted (IPC 2024, 111.4.3).

The tests themselves are the applicable ones from Sections 312.2 through 312.11, the permit holder giving reasonable advance notice when the work is ready and being responsible for determining that the work will withstand the prescribed pressure; piping is tested with water or, for systems other than plastic, with air, and after the fixtures are set and their traps filled the entire drainage system is submitted to final tests (IPC 2024, 312.1), with gauge increments of 0.10 psi or less up to a 10 psi test, 1 psi or less above 10 psi and up to 100 psi, and 2 psi or less above 100 psi (IPC 2024, 312.1.1). A water test fills the system, or holds each section under not less than a 10-foot head with at least the upper 10 feet of the preceding section retested, for at least 15 minutes with the system then tight at all points (IPC 2024, 312.2); plastic piping is not tested with air, the air test holding a uniform 5 psi, or a 10-inch column of mercury, for at least 15 minutes (IPC 2024, 312.3); the vacuum test holds a uniform negative 5 psi, or a negative 10-inch mercury column, for 15 minutes (IPC 2024, 312.4); and the final test is visual, a smoke test holding the equivalent of a 1-inch water column for at least 15 minutes (IPC 2024, 312.5). A water supply system is proved tight at not less than its working pressure, or by an air test of at least 50 psi for systems other than plastic, held for at least 15 minutes with water from a potable source (IPC 2024, 312.6); the gravity sewer test holds a 10-foot head and the forced sewer test the pump rating plus 5 psi, each for 15 minutes (IPC 2024, 312.7, IPC 2024, 312.8); a storm drainage system is tested by water or air (IPC 2024, 312.9); a shower liner holds potable water to at least 2 inches at the threshold for at least 15 minutes with no evidence of leakage (IPC 2024, 312.10); and backflow prevention assemblies and air gaps are inspected annually (IPC 2024, 312.11.1), the assemblies being tested at installation, immediately after repair or relocation, and at least annually (IPC 2024, 312.11.2).

7. Violations and stop work orders

A board of appeals hears and decides appeals of the orders, decisions and determinations of the code official on the application and interpretation of the code, and renders its decisions and findings in writing to the appellant with a copy to the official (IPC 2024, 112.1). An appeal rests on a claim that the intent of the code was incorrectly interpreted, that its provisions do not fully apply, or that an equivalent or better form of construction is proposed, and the board has no authority to waive a requirement of the code (IPC 2024, 112.2). Its members are qualified by experience and training on matters pertaining to the code and are not employees of the jurisdiction (IPC 2024, 112.3), the official acting without delay on the board's decision (IPC 2024, 112.4), and the board consists of five members serving initial terms of 5, 4, 3, 2 and 1 year and thereafter 5 years each (IPC 2024, 113.1).

Work done in conflict with the code is unlawful (IPC 2024, 114.1). The official serves a notice of violation or an order on the person responsible, directing the discontinuance of the illegal action or condition and the abatement of the violation (IPC 2024, 114.2), and if it is not complied with promptly the official requests the jurisdiction's legal counsel to institute the appropriate proceeding at law or in equity to restrain, correct or abate the violation (IPC 2024, 114.3). A person who violates the code, fails to comply with its requirements, or works contrary to the approved construction documents, a directive of the official, or a permit or certificate issued under the code is guilty of the offence the jurisdiction specifies, punishable by the fine or imprisonment the code leaves to be inserted, each day a violation continues after due notice being a separate offence (IPC 2024, 114.4), and those penalties do not preclude other action to prevent unlawful construction, restrain, correct or abate a violation, prevent illegal occupancy, or stop an illegal act, conduct, business or utilization of plumbing (IPC 2024, 114.5).

Plumbing that is unsafe, or that constitutes a fire or health hazard, an insanitary condition, or is otherwise dangerous to human life, is declared unsafe, and plumbing whose use is a hazard by reason of inadequate maintenance, dilapidation, obsolescence, fire hazard, disaster, damage or abandonment is an unsafe use and a public nuisance, to be abated by repair, rehabilitation, demolition or removal (IPC 2024, 114.6). Where the official determines that plumbing or a portion of it has become hazardous to life, health or property or unsanitary, the official orders in writing that it be removed or restored to a safe or sanitary condition, with a time limit for compliance, and a person must not use or maintain defective plumbing after receiving that notice; where it is to be disconnected, written notice is given as Section 114.2 prescribes, except that in cases of immediate danger to life or property the disconnection is made immediately without that notice (IPC 2024, 114.6.1). A person must not make connections to, or supply energy, fuel or water to, equipment that has been disconnected or ordered disconnected or whose use has been ordered discontinued, until the official authorises reconnection and use (IPC 2024, 114.6.3).

A stop work order is available where the official finds work regulated by the code being performed contrary to its provisions or in a dangerous or unsafe manner (IPC 2024, 115.1). It is in writing, given to the owner, the owner's authorized agent or the person performing the work; on issuance the cited work immediately ceases, and the order states the reason and the conditions under which the work may resume (IPC 2024, 115.2). In an emergency the official need not give written notice before stopping the work (IPC 2024, 115.3), and a person who continues work after being served with a stop work order, other than work directed to be done to remove a violation or unsafe condition, is subject to the fines established by the authority having jurisdiction (IPC 2024, 115.4).

8. How plumbing must be installed and protected

Section 301 sets the ground rules. Plumbing is installed with due regard to preserving the strength of structural members and preventing damage to walls and other surfaces through fixture usage (IPC 2024, 301.2). Fixtures, drains, appurtenances and appliances that receive or discharge liquid waste or sewage are directly connected to the sanitary drainage system in accordance with the code, without preventing the indirect waste systems the chapter on indirect and special waste requires (IPC 2024, 301.3); bathtubs, showers, lavatories, clothes washers and laundry trays need not discharge to the sanitary drainage system where they discharge to an approved system under the chapters on nonpotable water and graywater (IPC 2024, 301.3). Every fixture, device or appliance needing or using water is directly or indirectly connected to the water supply system (IPC 2024, 301.4), pipe, tube and fitting sizes are expressed in nominal or standard sizes as designated in the referenced material standards (IPC 2024, 301.5), a plumbing system is not placed in an elevator shaft or an elevator equipment room (IPC 2024, 301.6), and where the code conflicts with the manufacturer's installation instructions the more restrictive provision applies (IPC 2024, 301.7).

Section 302 excludes materials from the drainage and sewer system: ashes, cinders, rags, flammable, poisonous or explosive liquids or gases, oil, grease and any other insoluble material capable of obstructing, damaging or overloading the building drainage or sewer system or interfering with treatment processes are not deposited into those systems by any means (IPC 2024, 302.1), and industrial or manufacturing waste products do not enter a public sewer until the code official or other authority having jurisdiction has determined that doing so will neither damage the public sewer system nor interfere with the sewage treatment plant (IPC 2024, 302.2).

Section 303 governs the materials. Each length of pipe and each fitting, trap, fixture, material and device bears the identification of the manufacturer and the markings the applicable referenced standards require (IPC 2024, 303.1). Materials are installed in strict accordance with the standards under which they were accepted, and in the absence of such installation procedures the manufacturer's instructions are followed; where a referenced standard or manufacturer's instruction does not conform to a minimum provision of the code, the code applies (IPC 2024, 303.2). Plastic pipe, fittings and components are third-party certified as conforming to NSF 14 (IPC 2024, 303.3), and products the code requires to comply with a referenced standard are listed by a third-party certification agency as complying with it (IPC 2024, 303.4). Cast-iron soil pipe and fittings, and the couplings joining them, are third-party listed and labeled (IPC 2024, 303.5).

Rodentproofing is a plumbing obligation: systems are designed and installed to keep rodents out of structures (IPC 2024, 304.1), strainer plates on drain inlets have no opening greater than 1/2 inch in least dimension (IPC 2024, 304.2), meter boxes are built so that rodents cannot enter a structure along the water service pipes connecting the meter box and the structure (IPC 2024, 304.3), and openings made in walls, floors or ceilings for the passage of pipes have the annular space between the pipe and the sides of the opening sealed with caulking or closed with gasketing systems compatible with the piping materials and the locations (IPC 2024, 304.4).

Section 305 protects pipes and components, and it is the section most often quoted on an inspection. Metallic piping other than cast iron, ductile iron and galvanized steel is not placed in direct contact with steel framing members, concrete or cinder walls and floors, or other masonry, and metallic piping is not placed in direct contact with corrosive soil; where sheathing prevents that contact it is at least 0.008 inch (8 mil) thick and made of plastic, and where it protects piping penetrating concrete or masonry walls or floors it is installed so as to allow the piping to move within it (IPC 2024, 305.1). Piping is installed so as to prevent strains and stresses exceeding the structural strength of the pipe, and where necessary provisions are made to protect it from damage due to expansion, contraction and structural settlement (IPC 2024, 305.2). A pipe passing through a foundation wall is provided with a relieving arch, or a pipe sleeve built into the wall, the sleeve being two pipe sizes greater than the pipe passing through it (IPC 2024, 305.3). Water, soil and waste pipes are not installed outside a building, in attics or crawl spaces, concealed in outside walls, or anywhere subjected to freezing temperatures, unless adequate provision is made to protect them from freezing by insulation or heat or both; exterior water supply piping is installed at least 6 inches below the frost line and at least 12 inches below grade (IPC 2024, 305.4). The printed line on sewer depth gives no value in this edition: the depth below finished grade at the point of septic tank connection and the depth below grade are printed as placeholders for the adopting jurisdiction, so no depth is stated here (IPC 2024, 305.4.1). Joints at the roof and around vent pipes are made watertight with lead, copper, galvanized steel, aluminum, plastic or another approved flashing or flashing material, and exterior wall openings are made watertight (IPC 2024, 305.5). Two rules carry numbers a plumber uses daily: in concealed locations, piping other than cast iron or galvanized steel installed through holes or notches in studs, joists, rafters or similar members less than 1 1/4 inches from the nearest edge of the member is protected by steel shield plates, which cover the area of the pipe where the member is notched or bored and extend at least 2 inches above sole plates and below top plates (IPC 2024, 305.6), those plates being steel of at least 0.0575 inch (No. 16 gage) thickness (IPC 2024, 305.6.1). Components installed along alleyways, driveways, parking garages or other locations exposed to damage are recessed into the wall or otherwise protected in an approved manner (IPC 2024, 305.7). Where expansive soil is identified under a building in accordance with the International Building Code and is not removed, plumbing is protected under Section 305.8: under a foundation with a slab structurally supported by a subgrade, buried plumbing is permitted (IPC 2024, 305.8.1); under a slab or framing that structurally spans an under-floor space and is isolated from the effects of expansive soil swelling and shrinking, the plumbing is suspended so that plumbing, hangers and supports are isolated by a void space from those effects, with the soil sloped, benched or retained under an approved design methodology (IPC 2024, 305.8.2).

9. Trenching, structural safety and support

Buried piping is supported throughout its entire length (IPC 2024, 306.1), on a bed that is solid and continuous between joints, with bell holes, hub holes and coupling holes at the joints and no support on blocks to grade (IPC 2024, 306.2); an overexcavated trench is backfilled to the installation level with sand or fine gravel in layers not more than 6 inches deep, compacted each time (IPC 2024, 306.2.1); rock is removed to at least 3 inches below that level and replaced with tamped sand (IPC 2024, 306.2.2); plastic sewer piping carries an insulated copper tracer wire or another approved conductor over its full length, of not less than 14 American Wire Gauge with direct-burial insulation (IPC 2024, 306.2.4); and backfill is free of construction debris, placed in 6-inch layers and tamped until the crown of the pipe is covered by 12 inches of tamped earth (IPC 2024, 306.3). Section 307 keeps the building sound while that work is done, leaving changed floors, walls, ceilings and tile work in a safe structural condition and keeping trenching out of the bearing plane of footings and walls (IPC 2024, 307.1, IPC 2024, 307.6), and Section 308 supports the piping: hangers, anchors and supports carry the pipe and its contents and attach to the building construction in an approved manner (IPC 2024, 308.3, IPC 2024, 308.4), the interval coming from the hanger spacing table, which reads 4 feet horizontally and 10 feet vertically for ABS pipe, 5 feet horizontally (10 feet where 10-foot lengths are used) and 15 feet vertically for cast-iron pipe, 12 feet horizontally and 10 feet vertically for copper or copper-alloy pipe, and 12 feet horizontally and 15 feet vertically for steel pipe (IPC 2024, 308.5, IPC 2024, Table 308.5), with rigid bracing where horizontal pipe 4 inches and larger turns more than 45 degrees (IPC 2024, 308.6) and anchorage at every change in direction and in diameter greater than two pipe sizes for pipe larger than 4 inches (IPC 2024, 308.7.1).

10. Penetrations and closing

The annular space between a pipe and a pipe sleeve, or between a pipe and an opening in a building envelope wall, floor or ceiling assembly, is sealed with caulking, foam sealant or a gasketing system compatible with the pipe, sleeve and building materials, and where the penetration is of a fire-resistance-rated assembly the sealing follows Section 714 of the International Building Code (IPC 2024, 315.1). Where a design cannot be built to the letter of the code, an alternative engineered design conforms to the intent of the code and provides an equivalent level of quality, strength, effectiveness, fire resistance, durability and safety (IPC 2024, 316.1.1), through a documented submittal including floor plans and a riser diagram that shows where appropriate the direction of flow, all pipe sizes, the grade of horizontal piping, the loading, and the location of fixtures and appliances (IPC 2024, 316.1.4), tested and inspected under Sections 111 and 312 (IPC 2024, 316.1.6).

In practice the general regulations are applied from the outside in. First the scope and purpose of the code, to establish that the work is subject to it at all (IPC 2024, 101.2, IPC 2024, 101.3). Then the applicability rules (IPC 2024, 102.1, IPC 2024, 102.2, IPC 2024, 102.8.1). Then the permit, required before the work begins and defining the work approved (IPC 2024, 105.1, IPC 2024, 105.5.1). Then the construction documents that fix what will be built (IPC 2024, 106.1). Then the inspections at the three printed stages, followed by the tests of Section 312 (IPC 2024, 111.2, IPC 2024, 312.1). And throughout, the installation rules of the general regulations chapter: connection to the drainage and water supply systems, materials and their identification, rodentproofing and sealing of openings, protection of the pipe from contact, stress, freezing and physical damage, trenching and backfill, structural safety, and support at the printed intervals (IPC 2024, 301.3, IPC 2024, 303.1, IPC 2024, 304.4, IPC 2024, 305.4, IPC 2024, 306.2, IPC 2024, 307.1, IPC 2024, 308.5). Every value in this text was read from a printed line of the 2024 edition, and the one place where the printed line carries no value says so.