AK Plumber cheat sheet

A plumbing permit is required before installing, altering, or repairing any plumbing system; ordinary minor repairs and stoppage clearing are typically exempt.

"Approved" means accepted by the authority having jurisdiction (AHJ); "listed" means included in a published list by an approved testing agency.

A potable water supply is water free of impurities in amounts that could constitute a health hazard; it must meet the primary drinking water standards.

Fixtures must be installed to allow cleaning and be accessible for inspection; concealed piping requires the AHJ's approval before covering.

Inspections commonly required: rough-in (before covering), final, and special inspections for water heater or gas installations.

A plumbing contractor must hold a valid license and be bonded where required; work performed without a permit is subject to penalty and removal.

Definitions of "fixture unit," "developed length," "stack," and "branch" drive sizing calculations; misapplying them is a common code error.

The AHJ may require corrections and re-inspection; work not corrected within the stated period may be condemned or ordered removed.

A fixture unit (FU) is a measure of the probable load a fixture places on the drainage or supply system; values are tabulated by fixture type.

Total drainage fixture units (DFU) sum across fixtures on a branch; convert to pipe diameter using the slope-dependent drainage tables.

Drainage pipe slope: 1/4 in. per ft is standard for 2-1/2 in. and smaller; 1/8 in. per ft may be allowed for 3 in. and larger where the table permits.

Developed length is the total measured pipe length plus equivalent lengths for fittings; it is used for gas and water sizing.

Water supply sizing uses fixture units converted to probable demand in gallons per minute; velocity should be kept in the 4-8 ft/s range.

Pressure loss through fittings is often estimated by adding equivalent lengths (e.g., 90-degree elbow adds several pipe diameters of length).

Gas pipe sizing uses the longest run method: measure the longest path from meter to the farthest appliance, then use the capacity table for that length.

Slope conversion: percent slope = (rise / run) x 100; a 1/4 in./ft slope equals approximately 2.08 percent.

Every fixture that discharges to the drainage system must be trapped, except for fixtures that drain directly to a floor drain or are specifically exempted.

Trap seal depth must be 2 to 4 in.; a trap must be self-cleaning and its developed length of trap arm is limited by pipe size.

A vent stack must extend at least 6 in. above the roof, and the vent terminal must be at least 10 ft horizontally from or 2 ft above any window or air intake.

Vent pipe diameter must be at least half the diameter of the drain it serves, and no smaller than 1-1/4 in.

The flood-level rim of a fixture must be at least 6 in. above the trap seal; a fixture set lower requires a backwater valve or special protection.

A trap arm may not exceed the distance permitted by the table (e.g., 5 ft for 1-1/2 in. pipe) without a vent, or the trap will siphon.

A wet vent is a vent that also serves as a drain; it is permitted only where the code allows and the fixture load and pipe size comply.

Horizontal drainage piping must be supported at intervals not exceeding 4 ft; vertical stacks must be supported at each floor or as specified.

Minimum static pressure at a fixture is typically 8 psi (15 psi for some fixtures); maximum pressure in the system is commonly 80 psi, requiring a pressure-reducing valve above that.

A water service line must be buried below the frost line; local frost depth governs the minimum cover.

Backflow prevention is required where a cross-connection could contaminate potable water; devices include air gaps, vacuum breakers, and RPZ assemblies.

Water distribution piping must be protected from freezing; exposed piping in unheated spaces requires insulation or heat tracing.

A water service must be protected from contamination by being separated horizontally from sanitary sewer lines (typically 5 ft) and crossing above them.

Shutoff valves must be provided on each fixture supply and on the main service; a full-open valve is required on the service.

Water hammer arrestors protect against hydraulic shock; they are installed near quick-closing valves and appliances.

Pipe sizing for water supply uses the longest length method and the fixture-unit-to-gpm conversion tables.

A water closet must have a minimum 15 in. from its centerline to any side wall and 21 in. of clear space in front of the bowl.

Fixture clearances: 30 in. minimum width for a shower or tub area; a lavatory requires 15 in. from centerline to a side wall.

Each fixture must have a water-supply shutoff valve, and the supply line must be accessible for repair.

A floor drain must have a trap with a removable strainer; trap primers are required where the trap could evaporate.

Dishwashers must have a backflow-prevention device (air gap or high-loop) and connect to the drain through an approved fitting.

Fixture drains must be sized to the fixture's drain outlet; a fixture with a 2 in. drain outlet cannot connect to a 1-1/2 in. drain.

Water closets must be listed and have a maximum flush volume in accordance with local water-conservation rules.

A clothes washer requires a standpipe and trap; the standpipe must extend above the trap and be accessible.

A temperature and pressure relief (T&P) valve is required on every storage water heater; its discharge must terminate 6 to 24 in. above the floor and be piped to a safe location.

The T&P valve rating must not exceed the heater's rated working pressure or the maximum temperature rating (typically 210 degrees F).

A water heater must be anchored or strapped in seismic zones and protected from physical damage.

Expansion tanks are required in closed systems where thermal expansion cannot be relieved through the T&P valve.

A water heater must have a shutoff valve on the cold inlet and a drain valve; gas heaters require a sediment trap and proper venting.

Storage water heaters must be vented with a listed vent system; the vent must rise at least 1/4 in. per ft and terminate above the roof.

Scald protection is required at shower valves and tub-shower combinations in many jurisdictions; limit stops or thermostatic mixing valves are used.

Water heater flue clearance to combustibles follows the listing; single-wall vent pipe requires 6 in. clearance.

A building drain is the lowest piping that receives the discharge from soil and waste stacks and conveys it to the building sewer; the building sewer runs from the building to the public sewer.

A cleanout is required at the base of each soil stack, at the building drain, and at changes of direction greater than 135 degrees.

Storm drainage must not connect to the sanitary sewer; roof drains, area drains, and foundation drains are separate systems.

A backwater valve is required on a building sewer where the fixture flood-level rim is below the elevation of the next upstream manhole.

Special waste (chemical, corrosive, or grease-laden) requires pretreatment; grease interceptors are required for commercial kitchens.

A grease interceptor must be sized according to the fixture load and have a minimum 2 in. inlet and outlet, with flow-control fittings.

Vertical drainage stacks must be offset at least 45 degrees or supported; horizontal branch connections must be made with approved fittings.

Drainage piping must be tested with water or air before being concealed; the water test must maintain the required head for the specified period.

Gas piping must be sized using the longest-run method; the longest run from the meter to the farthest appliance determines the pipe size.

A sediment trap must be installed on the gas line ahead of each appliance's controls to catch debris.

A shutoff valve must be installed within 6 ft of each appliance and be accessible; a union is required between the valve and the appliance.

Combustion air for appliances in a confined space may be provided by two permanent openings: one near the top and one near the bottom of the enclosure.

For indoor air, each opening must have a free area of at least 1 sq in. per 1,000 Btu/h of total input; outdoor air openings use 1 sq in. per 4,000 Btu/h.

Gas piping must be tested for leaks with air or inert gas at the pressure specified by the code (commonly 10 psi for a fixed period) before being placed in service.

Gas vents must terminate above the roof and away from windows, doors, and air intakes; clearance is set by the listing and code.

A gas appliance must not be installed where it is subject to physical damage or where the combustion air is contaminated by corrosive vapors.

Before excavating, call the utility locating service; hand-dig near marked utilities and maintain the required clearance.

Shoring or sloping is required for trench excavations 5 ft or deeper; a competent person must inspect the trench daily.

Confined spaces (tanks, vaults, sewers) require atmospheric testing, ventilation, and a trained attendant before entry.

Personal protective equipment includes eye protection, gloves, and hearing protection when cutting or using power tools.

Soldering and brazing require fire protection: a fire watch and removal or shielding of combustibles near the work area.

Backflow and cross-connection hazards must be controlled on the jobsite; temporary connections to potable water need air gaps or backflow devices.

Ladder use: maintain a 4:1 slope, extend 3 ft above the landing, and secure the top; never stand on the top two rungs.

Electrical safety: use ground-fault protection on temporary power, and lock out/tag out before servicing equipment.