NBOPE/IAPMO Master Plumber cheat sheet

Model codes (IPC, UPC) are adopted and amended by the local authority having jurisdiction (AHJ); the adopted edition and local amendments control over the model text.

Permits are required before installation, alteration, replacement, or repair of a plumbing system except for specified minor work such as stoppage clearing, faucet or valve repair, or fixture replacement with no piping change.

A permit application typically requires the scope of work, occupancy, owner and contractor information, and payment of fees; work may not begin until the permit is issued.

Inspections are required at defined stages: rough-in (piping and venting in walls before concealment), water and drain testing, and final inspection after fixtures, trim, and labeling are complete.

Concealed work must be inspected and approved before covering; the AHJ may order exposure of work that was concealed without inspection.

A plumbing contractor must hold a license or registration in the jurisdiction and must be bonded and insured; a master plumber must hold a current license in the state.

An approved set of plans and the permit must be kept on the job site and made available to the inspector on request.

Code editions take effect on a published date; work permitted under an earlier edition may generally proceed under that edition if construction is continuous and completed within the time limit.

The AHJ has authority to interpret the code, grant alternate methods or materials of equivalent performance, and issue stop-work orders for noncompliant work.

Water supply sizing uses the method of assigning water supply fixture units (WSFU) to each fixture, deriving the total demand in gpm (or L/s) from a conversion table, then applying the Hunter curve / demand-load table.

Minimum residual pressure at the fixture: about 8 psi for flush-tank water closets and 15-20 psi for flushometer valves (per the adopted code and manufacturer's requirements).

Allowable pressure loss in the distribution system equals the static pressure at the building minus the fixture demand minus losses from elevation, meter, and developed length.

Pressure loss from elevation is approximately 0.433 psi per foot of rise (1 psi per 2.31 ft).

Developed length includes the horizontal and vertical run plus fittings; if the actual developed length is not known, add approximately 50 percent to the measured pipe length.

Velocity in water supply piping is typically limited to 8 ft/s (2.4 m/s) in cold water and 5 ft/s (1.5 m/s) in hot water to control noise and erosion.

Common potable water materials: copper (types K, L, M), PEX, CPVC, PEX-AL-PEX, and galvanized steel; lead pipe and lead solder are prohibited in potable systems.

Copper and steel must be separated by a dielectric union or approved insulator to prevent galvanic corrosion.

A pressure-reducing valve is required where static pressure exceeds about 80 psi, and an expansion tank is required on a closed system.

Drainage fixture unit (DFU) values come from the code table for each fixture; the building drain and sewer are sized from the total DFU and slope using the drainage sizing table.

Slope requirements: 1/4 in. per foot for pipe 2-1/2 in. and smaller; 1/8 in. per foot is permitted for 3 in. and larger pipe in many codes.

A trap is required for every fixture (except fixtures with integral traps and certain fixtures listed in the code), and each trap must have a vent.

Trap seal depth is 2 to 4 in.; a trap arm length is limited so that the vent connection is not more than the developed length listed for the trap arm diameter.

Every building must have at least one main vent through the roof, extending at least 6 in. above the roof and not less than 12 in. from any vertical surface, with the size not less than the building drain size.

A vent stack is required for stacks of more than a set number of branch intervals (commonly 5 for stacks of 3 in. and larger), and a relief vent may be required.

Horizontal drainage piping must be supported at intervals not exceeding 4 ft, and vertical pipe at each floor and not more than 10 ft.

Cleanouts are required at the base of each stack, at the building sewer, at changes of direction greater than 45 degrees, and at intervals not exceeding 100 ft in horizontal runs.

Air admittance valves may substitute for individual or branch vents where permitted by the adopted code, but not for the main building vent through the roof.

Storm drainage sizing uses the 100-year, 60-minute rainfall intensity for the location and the roof area to compute flow: Q = area x intensity, converted to gpm.

Roof drains and leaders are sized from the rainfall rate and roof area using the storm drainage sizing table; the size must handle the design storm.

Sizing the roof drainage system for a smaller storm than the design storm is permitted only where overflow scuppers or secondary drainage of adequate capacity is provided.

Secondary (overflow) roof drainage must discharge to a location that is visible to building occupants, not to the storm sewer where it can go unnoticed.

Storm drainage may not connect to the sanitary drainage system; combined systems are permitted only where the local sewer is a combined sewer and the AHJ allows it.

Special wastes such as acid, grease, oil, or chemical wastes require approved interceptors or neutralization tanks and must not discharge to the sanitary sewer without treatment.

Grease interceptors are required for commercial kitchens and are sized by the fixture unit method or the code formula; the interceptor must be accessible for cleaning.

Indirect waste receptors receive waste from fixtures such as ice machines, dishwashers, and sterilizers and must discharge through an air gap or air break.

Storm drainage piping is tested by filling with water or by air test where permitted, and must be inspected before concealment.

Water supply fixture unit (WSFU) and drainage fixture unit (DFU) values are assigned per fixture; convert WSFU to gpm using the demand table and DFU to pipe size using the drainage table.

A water closet is 1.6 gpf (6 Lpf) maximum in current codes; urinals are 1.0 gpf or less; showerheads are 2.5 gpm at 80 psi; lavatory faucets are 2.2 gpm or less.

A public lavatory is 1 WSFU and 1 DFU; a private lavatory is 1 WSFU and 1 DFU; a bathtub is 2 WSFU and 2 DFU; a shower is 2 WSFU and 2 DFU.

A water closet is 2.5 WSFU and 3 DFU (flush tank) or 6 DFU (flushometer valve); a kitchen sink is 1.5 WSFU and 2 DFU.

Fixture unit totals must be computed for the building and for each branch; branch sizing uses the branch DFU table and the branch WSFU table.

Approved fixtures must be installed level and secure, with the fixture outlet and trap accessible for cleaning unless a listed fixture has a concealed trap.

Water closets must be installed with a water seal of at least 2 in. and a trapway; floor flanges must be securely fastened and sealed to the drain.

Fixture clearances: at least 15 in. from the centerline of a water closet to any side wall, and 30 in. of clear space in front of the fixture.

Backflow protection is required at fixtures with a submerged inlet, such as a hose bibb or a flushometer valve, by an approved vacuum breaker.

A temperature and pressure relief (T&P) valve is required on every storage water heater; the valve must be rated for the tank's working pressure and temperature and must be piped to a safe discharge point.

The T&P discharge pipe must be full size, not reduced, not trapped, and must terminate not more than 6 in. above the floor or outside the building.

A thermal expansion tank is required on a closed potable water system with a storage water heater to absorb expansion and prevent T&P valve discharge.

Water heater temperature settings: about 120 degrees F (49 degrees C) for domestic use; storage at 140 degrees F with a mixing valve to limit delivery to 120 degrees F is common for Legionella control.

A tempering or mixing valve is required at fixtures used by children, elderly, or disabled persons to limit hot water delivery to about 110-120 degrees F.

A water heater must be installed with a drain pan where leakage could cause damage, with the pan drain discharging to an approved location.

Gas water heaters require combustion air and venting per the gas code; a draft hood or power vent must be installed per the manufacturer's instructions.

Water heaters must be secured against seismic movement where required by the local code, using approved straps or anchors.

A water heater must be accessible for service, and the T&P valve must be accessible and not concealed.

Gas piping sizing uses the longest length method or the branch length method with the gas load in cubic feet per hour (CFH) and the allowable pressure drop.

Gas pipe sizing tables depend on the gas type (natural gas or LP), the specific gravity, the pressure, and the allowable pressure drop; the table used must match the gas supplied.

Pipe sizing must account for the total connected load and the diversity factor; the meter and regulator capacities must be adequate for the load.

Gas piping must be tested with air or inert gas at a pressure specified by the code (commonly 10 psi for 30 minutes for systems up to a set pressure, or 3 psi for 10 minutes for low-pressure systems).

Combustion air for fuel-burning appliances is provided by the indoor air infiltration method, the indoor air volume method, or the outdoor air method; each has a required volume or opening size.

The outdoor air method requires openings sized at 1 sq in. per 4,000 Btu/h of input for vertical ducts or 1 sq in. per 2,000 Btu/h for horizontal ducts.

Venting of gas appliances must follow the appliance category (I, II, III, IV) and the manufacturer's listing; a Category I appliance uses a natural draft vent.

Gas piping must be supported at intervals not exceeding 6 ft and must be protected against corrosion and physical damage.

A shutoff valve must be installed upstream of each appliance, and a sediment trap must be installed at the appliance connection.

A cross-connection is any actual or potential connection between the potable water system and a source of contamination; it must be eliminated or protected by an approved backflow preventer.

Backsiphonage is caused by negative pressure in the supply; backpressure is caused by downstream pressure exceeding supply pressure.

An air gap is the highest level of protection and requires a physical separation of at least twice the effective opening of the outlet, with a minimum of 1 in.

A reduced pressure principle assembly (RPZ) provides protection against both backsiphonage and backpressure and is required for high-hazard connections.

A double check valve assembly provides protection against backsiphonage only and is used for low-hazard connections.

A pressure vacuum breaker (PVB) protects against backsiphonage only and must be installed at least 12 in. above the highest downstream outlet.

A hose bibb vacuum breaker is an inexpensive device for hose connections and is not a substitute for a testable assembly where a testable assembly is required.

Testable backflow assemblies must be tested at installation and at least annually by a certified tester, and the test report must be filed with the water authority.

A thermal expansion control device is required on a closed system protected by a backflow preventer because the preventer creates a closed system.

Health care facilities require special plumbing systems: medical gas piping, vacuum systems, purified water, and emergency fixtures, each governed by NFPA 99 and the adopted plumbing code.

Medical gas piping must be installed by an ASSE 6010-certified installer and verified by an independent third party before use.

Medical gas outlets must be labeled and the piping system must be tested for purity and pressure; the system must be brazed with nitrogen purge.

Health care facilities require hot water at temperatures that control Legionella, often with a recirculating hot water system and a mixing valve at the point of use.

Emergency eyewash and shower stations must be located within 10 seconds of travel (about 55 ft) of the hazard and must deliver tepid water (60-100 degrees F).

Clinical sinks, bedpan washers, and sterilizers require indirect waste connections with an air gap or air break.

Dialysis and laboratory water systems may require purified water and special materials such as stainless steel or PVDF to prevent contamination.

Health care facilities require a backflow prevention program with testable assemblies at high-hazard connections and annual testing.

Plan views show the building layout from above; the plumbing plan shows fixture locations, pipe routes, and riser diagrams with pipe sizes and slopes.

A riser diagram is a schematic vertical view of the system; it shows pipe sizes, fixture connections, vents, and the building drain and sewer.

An isometric drawing shows the system in three dimensions; it is used to interpret offsets, changes in elevation, and the route of the pipe in the building.

The scale of a drawing is the ratio of drawing distance to actual distance; a 1/4 in. = 1 ft scale means 1/4 in. on the drawing equals 1 ft in the building.

The plumbing plan must show the location of the water service, the building sewer, the water meter, and the main shutoff valve.

A section drawing shows a cut through the building and is used to verify pipe elevations, clearances, and the location of concealed piping.

Drawing symbols for plumbing include the water closet, lavatory, sink, floor drain, and cleanout; a legend on the drawing defines the symbols used.

A bill of materials is taken off the drawings by counting fixtures and measuring pipe runs; the takeoff must include fittings, valves, and hangers.

Coordination with structural, mechanical, and electrical drawings is required to avoid conflicts and to verify sleeve and penetration locations.

A bid estimate includes material, labor, equipment, subcontractor, overhead, and profit; the total is divided by the quantity to get the unit price.

Labor cost is estimated by multiplying the labor hours per unit by the installed quantity and the crew's hourly rate, including burden (payroll taxes, insurance, and benefits).

Overhead includes office rent, insurance, vehicles, tools, and administrative salaries; it is typically applied as a percentage of direct cost.

A change order documents a change in scope, price, and time; it must be signed by the owner or the owner's representative before the work proceeds.

A retainage of 5-10 percent is commonly withheld from progress payments until final acceptance and punch list completion.

A lien is a legal claim against the property for unpaid work; a preliminary notice and a mechanics lien are governed by state statute and deadlines.

A schedule of values allocates the contract sum to work items and is the basis for progress payments; it must be approved by the owner or architect.

A punch list is a list of incomplete or defective work prepared at substantial completion; final payment is typically released after the punch list is cleared.

Contract documents include the agreement, general and supplementary conditions, specifications, and drawings; the order of precedence among them is defined in the contract.