Special Topics

Special Topics

Learning Objectives

Upon completing this chapter, you will be able to:

1.1 Scope and Hierarchy of Codes in Maryland

Maryland adopts the 2018 International Plumbing Code (IPC) as the base plumbing code, with state-specific amendments published in the Code of Maryland Regulations (COMAR). The Maryland State Board of Plumbing enforces licensing, while local jurisdictions (counties and municipalities) administer permits and inspections. The hierarchy of authority is: federal regulations (OSHA) > state statutes (Business Occupations Article, Title 9A) > COMAR regulations > local amendments > IPC technical provisions.

For the exam, remember that Maryland does not adopt the International Residential Code (IRC) plumbing chapters for one- and two-family dwellings; instead, the IPC applies to all buildings, including residential, unless a local jurisdiction has adopted a different code. The master plumber must know which local amendments exist in their jurisdiction, but the exam tests the state-level baseline.

1.2 Administrative Requirements and the Responsible Licensed Person

The Maryland State Plumbing Code (COMAR 09.17.01) requires that a master plumber be the “responsible licensed person” for any plumbing work performed by a business entity. This means you are accountable for code compliance, even if you do not personally perform the work. Key administrative points:

Exam Trap: Questions often ask who is responsible when a journeyman installs a system incorrectly. The answer is always the master plumber of record, not the journeyman, for licensing and code enforcement purposes.

1.3 Special Occupancies and Building Types

1.3.1 Health Care Facilities (Hospitals, Clinics, Nursing Homes)

The IPC defers to the Facility Guidelines Institute (FGI) and the Centers for Medicare & Medicaid Services (CMS) for plumbing requirements in health care occupancies, but the IPC’s general provisions still apply where not superseded. Key considerations:

Field Point: As the master plumber, you must verify that the water heater temperature at the point of use in patient areas does not exceed 120°F (49°C) unless a specific clinical need is documented. Install thermostatic mixing valves at the source, not at each fixture, to simplify maintenance.

1.3.2 Detention and Correctional Facilities

Detention facilities (jails, prisons, juvenile halls) require plumbing systems designed to resist vandalism and prevent use as weapons or hiding places. The IPC does not have a dedicated chapter for detention facilities, but the designer must apply the general code with heightened security in mind:

Exam Trap: A question may describe a “suicide-resistant” cell and ask which fixture is permitted. The correct answer is a combination fixture with no exposed water supply or drain lines and no accessible hanger or bracket that could support a ligature.

1.3.3 Public Buildings and Places of Assembly

For buildings with high occupant loads (theaters, schools, stadiums), the IPC’s fixture count tables (Chapter 29) govern the minimum number of water closets, lavatories, and drinking fountains. Key calculations:

Calculation Example: A school with 400 female students and 400 male students requires, per Table 2902.1, 1 water closet per 30 females (400/30 = 13.3, round up to 14) and 1 per 60 males (400/60 = 6.7, round up to 7). Lavatories are required at 1 per 40 females (10) and 1 per 40 males (10). Do not round down; the code requires the next whole number.

1.4 Backflow Prevention and Cross-Connection Control

1.4.1 Degrees of Hazard

The IPC (Chapter 6) classifies cross-connections into two hazard levels:

1.4.2 Approved Protection Devices

The type of backflow prevention required depends on the degree of hazard and the point of use:

Field Point: In Maryland, RPZ assemblies must be tested by a state-certified backflow prevention tester, and test reports must be submitted to the local water authority. The master plumber is responsible for ensuring that the tester is certified and that the report is filed on time.

Exam Trap: A question may describe a chemical feed pump injecting a dye into a water line. The dye is a non-health hazard (aesthetic), so a DCV is acceptable. If the chemical is a pesticide, it is a health hazard, requiring an RPZ or air gap.

1.5 Venting Systems in Complex Installations

1.5.1 Circuit Venting and Combination Waste and Vent

For battery of fixtures (e.g., a row of toilets in a public restroom), the IPC (Chapter 9) allows circuit venting, where one vent serves up to eight fixtures on a horizontal branch. Requirements:

Combination waste and vent (CWV) systems are permitted for floor drains and sinks where the drainage pipe is oversized (one full pipe size larger than required for drainage alone) and serves as both waste and vent. The CWV must not receive discharge from a water closet.

1.5.2 Vent Sizing and Distance

The maximum distance from a fixture trap to the vent is determined by the fixture drain size and the slope. For a 1¼-inch trap, the maximum distance is 3 feet 6 inches; for 2 inches, 5 feet; for 3 inches, 6 feet; for 4 inches, 10 feet. The vent pipe diameter must be at least half the diameter of the drain it serves, but never less than 1¼ inches.

Calculation Example: A 3-inch horizontal branch serving a battery of water closets requires a vent of at least 1½ inches (half of 3 inches). If the vent is longer than 40 feet, it must be increased to 2 inches per Table 906.1.

1.6 Water Supply Sizing and Pressure

1.6.1 Fixture Units and Demand

The IPC uses a system of fixture units (WSFU) to estimate water demand. Table E103.3 (informative annex) provides the conversion from WSFU to gallons per minute (gpm). For a building with a total of 100 WSFU, the estimated demand is approximately 48 gpm for a system with flush tanks, or 75 gpm for flush valves.

1.6.2 Pressure Requirements

The minimum water pressure at any fixture is 8 psi (flowing), and the maximum static pressure is 80 psi. If the static pressure exceeds 80 psi, a pressure-reducing valve (PRV) must be installed. The PRV must be accessible and have a bypass (unless the local jurisdiction prohibits bypasses for health hazard protection).

Field Point: When sizing a water service for a large building, use the Hunter’s curve (Table E103.3) and apply the friction loss calculation (Hazen-Williams formula) for the developed length of pipe. Do not simply add the gpm ratings of all fixtures; the probability of simultaneous use is accounted for in the fixture unit method.

1.7 OSHA Regulations for the Master Plumber (29 CFR 1926)

The master plumber, as the employer or supervisor on a construction site, must comply with OSHA’s construction standards. Key areas tested:

Exam Trap: A question may ask who is responsible for trench safety when a subcontractor (e.g., an electrician) is working in the same trench. The answer is the controlling contractor (often the general contractor), but the master plumber is responsible for their own employees. If the master plumber is the sole contractor, they are the controlling contractor.

1.8 Maryland-Specific Amendments and Local Jurisdiction

Maryland’s amendments to the 2018 IPC include:

Local jurisdictions (e.g., Montgomery County, Prince George’s County, Baltimore City) may have additional requirements, such as:

Field Point: Before starting work in a new jurisdiction, call the local plumbing inspector’s office and ask for a copy of their amendments. This is a mark of a professional master plumber and can save you from a failed inspection.

Code Navigation: Where to Find It

Common Exam Traps and How to Avoid Them

Final Field Point for the Master Plumber

As the responsible licensed person, your signature on a permit application certifies that the work will comply with all applicable codes. Before you sign, walk the job site, review the plans, and verify that the journeyman’s rough-in matches the approved drawings. In an open-book exam, your ability to quickly locate the correct table or section is more valuable than memorizing every number. Practice navigating the IPC’s table of contents and index, and mark your codebook with tabs for Chapter 29 (fixture counts), Chapter 6 (water supply), and Chapter 9 (vents). On the Maryland exam, you will have 2.4 minutes per question — enough time to look up a table if you know where to find it.