Exam Cheat Sheet · Quick Reference
Virginia Residential Plumber
Virginia · PSI Services Contractor
Verified, not estimated. Every figure below is drawn from the official exam structure we maintain — question counts, passing standard and topic weighting. Practice questions are grounded in the source law with statute citations. We omit any figure we can't verify rather than guess at it.
Total questions
50
Passing score
70%
Exam time
120 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
Virginia State Portion 50 questions
Standards of Practice
3 Q · 6%
Prohibited acts and misdemeanor violations for unlicensed contractingGrounds for license denial, suspension, and revocationLicense classes and contractor classifications (Class A, B, C)Exemptions from contractor licensing requirementsWritten contract requirements for residential contractorsReinstatement of expired licenses and status during lapse periodScope of plumbing work and residential plumber tradesman definitionDesignated employee responsibilities and re-examination authority
Standards of Conduct
2 Q · 4%
Grounds for disciplinary action and board sanctionsProhibited acts resulting in disciplinary actionReporting requirements for convictions and license suspensionsProhibition on license transfer or assignmentAbandonment and unjustified failure to complete contracted workMisrepresentation and false promises in the practice of the professionAiding or abetting unlicensed contractorsFailure to obtain required permits or inspections
Renewal and Reinstatement
1 Q · 2%
License expiration periods for plumbers and other tradesmenContinuing education requirements for plumbing license renewalRenewal fees for tradesman licensesRenewal notice procedures and regulant obligationsGrounds for denial of license renewalReinstatement fees and timeline following expirationMaximum reinstatement window and new application requirementsEffect of unpaid monetary penalties on renewal or reinstatement
Definitions
1 Q · 2%
Plumbing fixture and system component definitions (IPC Chapter 2)Drainage system terminology: building drain, building sewer, stack, branch, and related termsWater supply system terminology: potable water, backflow, cross-connection, and water distribution componentsVenting system terminology: vent stack, stack vent, circuit vent, air admittance valve, and related termsVirginia-specific definitions: residential plumber tradesman, plumbing work scope, journeyman, and masterTrap and seal terminology: trap seal, depth of trap seal, building trap, and indirect wasteInterceptor and appurtenance definitions: grease interceptor, backflow preventer types, and plumbing appurtenanceCode administration terms: approved, code official, accepted engineering practice, and alternative engineered design
Qualification for Licensure
1 Q · 2%
Education and experience requirements for residential plumber tradesman licensureEducation and experience requirements for journeyman plumber licensureExperience standards for master plumber licensureVerification of experience and education documentationExemptions from examination requirementsApplication procedures and fees for tradesman licensureOut-of-jurisdiction license recognition and reciprocityGrounds for denial or revocation of tradesman license
Drainage Waste and Vents
12 Q · 24%
Drainage fixture unit (DFU) values and system sizing tablesSlope requirements for horizontal drainage pipingCleanout requirements, placement, and clearancePipe joint methods by material type (ABS, PVC, cast iron, copper)Vent types and installation methods (individual, common, wet, circuit, stack, AAV)Vent pipe sizing and developed length requirementsTrap-to-vent distance limits and crown vent prohibitionsIndirect waste requirements, air gaps, and air breaks
Water Supply Systems
8 Q · 16%
Backflow prevention devices and assembliesPotable water protection and cross-connection controlWater service pipe materials, standards, and installationWater distribution pipe materials, joints, and connectionsPressure requirements, pressure-reducing valves, and booster systemsWater piping system sizing methods and fixture unit demandWater heater safety devices, relief valves, and discharge pipingHot water supply system requirements and thermal expansion control
Backflow Prevention
6 Q · 12%
Cross-connection control and prohibited connections to potable water systemsBackflow preventer device types, hazard classifications, and applicable standards (Table 608.1)Air gap requirements and minimum dimensions for potable water outletsReduced pressure principle backflow prevention assembly installation and applicationsVacuum breaker types, installation heights, and critical level requirementsBackflow protection for specific connections (boilers, irrigation systems, sprinkler systems, beverage dispensers, hose bibbs)Backflow prevention in nonpotable water systems when connected to potable supplyLocation, access, freeze protection, and relief port discharge requirements for backflow preventers
Storm Drainage Systems
4 Q · 8%
Rainfall rate determination using 100-year hourly data and geographic mapsStorm drain pipe sizing using flow rate tables and slope calculationsApproved materials for storm sewer, conductors, and subsoil drain pipeRoof drain requirements and flow rate calculations (Equation 11-1)Secondary (emergency) roof drains and scupper sizing requirementsSubsoil drains and sump pump systemsProhibited connections and disposal requirements for storm waterSiphonic and controlled flow roof drain systems
Plumbing Fixtures
4 Q · 8%
Minimum number of plumbing fixtures by occupancy classificationFixture installation requirements (clearances, spacing, and setting)Fixture material standards and product approvalsAccessible plumbing fixtures and toilet room requirements (ICC A117.1)Faucets and fixture fittings (shower valves, temperature limits, backflow protection)Flushing devices for water closets and urinalsWater heater safety devices (temperature/pressure relief valves, discharge piping, pans)Grab bars in toilet and bathing facilities (dimensions, structural strength, placement)
General Regulations
4 Q · 8%
Permit requirements, application procedures, and exemptionsCode official duties, authority, and inspection powersRequired inspection stages (underground, rough-in, and final)Testing requirements for drainage, vent, water supply, and backflow prevention assembliesProtection of pipes from freezing, physical damage, and corrosive contactTrenching, bedding, and backfill requirements for buried pipingPiping support intervals and hanger spacing by material typeProhibited materials and substances discharged into drainage systems
Interceptors and Traps
4 Q · 8%
Fixture trap requirements and installation dimensionsProhibited trap typesTrap seal depth and protection methodsGrease interceptor requirements and capacity sizingOil separator design and required locationsSand, solids, and specialty interceptor requirementsVenting, access, and maintenance of interceptors and separatorsIndirect waste piping and air gap/air break requirements
Key Distinctions
Flow pressurevsStatic pressure
Flow pressure is the pressure in the water supply pipe near the faucet or outlet while it is wide open and flowing, whereas static pressure is the no-flow pressure computed from elevation (height × 0.433 psi per foot).
IPC 2021 Page 2-4Developed lengthvsStraight-line (direct) distance
Developed length is measured along the centerline of the pipe and fittings (segments added together, e.g., 8 + 5 + 12 = 25 ft), while the straight-line distance is shorter and is not used for pipe takeoff or sizing.
IPC 2021 Page 2-3BacksiphonagevsCross connection
Backsiphonage is backflow of potentially contaminated water into the potable system caused by potable pressure falling below atmospheric pressure, while a cross connection is the physical connection or arrangement between a potable system and one containing water of unknown/questionable safety or steam, gas, or chemical.
IPC 2021 Section 202 DefinitionsIndividual vent 40 feet or less in developed lengthvsIndividual vent exceeding 40 feet in developed length
At 40 ft or less the vent is simply half the fixture drain size but never smaller than 1¼ in. (e.g., 1½ in. for a 3 in. drain at 18 ft; 1¼ in. for a 1½ in. drain at 34 ft), whereas a vent exceeding 40 ft (e.g., 44 ft) must be increased one nominal pipe size for its entire length.
IPC 2021 Section 906.2Water supply system test (Section 312.5)vsDrainage and vent air test (Section 312.3)
The water supply system is tested tight at water pressure not less than the working pressure of the system held not less than 15 minutes, while the DWV air test uses a uniform gauge pressure of 5 psi (or enough to balance a 10-inch mercury column) held not less than 15 minutes — and plastic piping shall not be tested with air.
IPC 2021 Section 312.5Metallic piping contact with steel framing, concrete, cinder walls/floors or masonryvsMetallic piping contact with corrosive soil
Cast iron, ductile iron and galvanized steel are excepted from the prohibition on direct contact with steel framing, concrete, cinder walls/floors and masonry, but the prohibition on direct contact with corrosive soil applies to ALL metallic piping with no exception.
IPC 2021 Section 305.1Fixture trap as a cleanout equivalent (708.1.6)vsRemovable P-trap serving as a cleanout (708.1.5, Exception 1)
A fixture trap or fixture with integral trap that is removable without altering concealed piping is acceptable as a cleanout equivalent, while Exception 1 addresses a removable P-trap with slip or ground joint connections serving as the cleanout for drain piping one size larger than the P-trap.
IPC 2021 Chapter 7 — Sanitary Drainage, Section 708.1.6Using a threaded cleanout opening to add a fixture or extend pipingvsPermitted alternative
Such use is prohibited except where another cleanout of equal size is installed with the required access and clearance.
IPC 2021 Chapter 7 — Sanitary Drainage, Section 708.1.12Reuse of piping previously used for nonpotable purposesvsDisinfection of that piping
Piping used for any purpose other than conveying potable water shall not be used for potable water; disinfection does not remove the prohibition.
IPC 2021 Section 608.11PVC hanger spacing, horizontalvsPVC hanger spacing, vertical
Table 308.5 permits maximum horizontal spacing of 4 feet for PVC, but maximum vertical spacing of 10 feet.
IPC 2021 Table 308.5Tradesman license renewal feevsTradesman license reinstatement fee
Renewal costs $160.00, but if renewal requirements are not completed within 30 days of expiration a $210.00 reinstatement fee (which includes the renewal fee) is required; all fees are nonrefundable and not prorated.
Virginia Board for Contractors Regulations (18 VAC 50-30), Page 22 (18 VAC 50-30-120 G)45-degree offset travel constant (1.414)vs60-degree offset travel constant (1.155)
Travel for a 45° offset equals the true offset × 1.414, while travel for a 60° offset equals the set × 1.155 (using 1.414 on a 60° offset is a common error).
Key Terms
Flow pressure IPC 2021 Page 2-4
The pressure in the water supply pipe near the faucet or water outlet while that faucet or outlet is wide open and flowing.
Developed length IPC 2021 Page 2-3
The length of a pipeline measured along the centerline of the pipe and fittings.
Backsiphonage IPC 2021 Section 202 Definitions
The backflow of potentially contaminated water into the potable water system resulting from the potable system pressure falling below atmospheric pressure of the fixtures, pools, tanks or vats connected to the potable distribution piping.
Cross connection IPC 2021 Section 202 Definitions
Any physical connection or arrangement between two otherwise separate piping systems, one containing potable water and the other water of unknown or questionable safety, or steam, gas or chemical, whereby flow from one system to the other is possible.
Area drain IPC 2021 Chapter 11
A drain in a paved court or yard that collects surface storm water.
Segmented loss method IPC 2021 Page E-4 (Section E103.3, Step 6)
A water pipe sizing method in which equipment losses (backflow preventers, check valves, softeners, tankless heaters, filters, strainers) of 8 to 30 psi are deducted and, where fitting sizes are unknown, 50 percent of the developed length is added to allow for fittings and valves.
Reduced pressure principle backflow preventer assembly IPC 2021 Page 3-5
A backflow prevention assembly that (like double check, pressure vacuum breaker, reduced pressure detector fire protection, double check detector fire protection, spill-resistant vacuum breaker assemblies and hose connection backflow preventers) must be tested at installation, immediately after repairs or relocation, and at least annually.
Annual backflow inspection (Section 312.10.1) IPC 2021 Section 312.10.1
Yearly inspection of all backflow prevention assemblies and air gaps to determine whether the assemblies are operable and air gaps exist.
Pipe-applied vacuum breaker IPC 2021 Section 608.16.4
A backflow device that must be installed not less than 6 inches above the flood level rim of the fixture, receptor or device served.
Steel shield plate (Section 305.6) IPC 2021 Section 305.6
Protection of not less than 0.0575 inch (No. 16 gage) steel required in concealed locations where piping other than cast iron or galvanized steel is installed through holes or notches in studs, joists, rafters or similar members less than 1¼ inches from the nearest edge; the plates shall cover the notched or bored area and extend not less than 2 inches above sole plates and below top plates.
Strainer plate (Section 304.2) IPC 2021 Section 304.2
A drain inlet plate designed and installed so that all openings are not greater than 1/2 inch in least dimension, to prevent rodents from entering structures.
Auxiliary drain pan (Section 314.2.3) IPC 2021 Section 314.2.3
A corrosion-resistant pan under cooling coils with a depth of not less than 1½ inches and not less than 3 inches larger than the unit or coil in width and length.
Cleanout access — concealed location (Section 708.1.11) IPC 2021 Chapter 7 — Sanitary Drainage, Section 708.1.11
A prohibited cleanout location, including a crawl space where the height from crawl space floor to the nearest obstruction along the path from the crawl space opening to the cleanout is less than 24 inches.
Cleanout plug requirements IPC 2021 Chapter 7 — Sanitary Drainage, Section 708.1.7
Cleanout plugs shall have a raised square head, countersunk square head, or countersunk slot head, and shall not be covered with mortar, plaster or any other permanent material (a trim cover does not change this).
Class A contractor (Code of Virginia § 54.1-1100) Virginia Board for Contractors Regulations (18 VAC 50-30), Code of Virginia § 54.1-1100
One who performs or manages construction, removal, repair or improvements when the total value in a single contract or project is $150,000 or more, or the total value of all such work in any 12-month period is $1 million or more.
Tradesman license term and continuing education (18 VAC 50-30-120) Virginia Board for Contractors Regulations (18 VAC 50-30), Page 22 (18 VAC 50-30-120 A)
Licenses for electricians, gas fitters, LP gas fitters, natural gas fitter providers, HVAC tradesmen and plumbers expire three years from the last day of the month of issuance, and each trade designation (plumbing, electrical, HVAC) requires 3 hours of board-approved continuing education on applicable building code changes for renewal or reinstatement.
Regulant reporting duties (18 VAC 50-30-160, -190) Virginia Board for Contractors Regulations (18 VAC 50-30), 18 VAC 50-30-160
A regulant must report any address change in writing within 30 days and must inform the board in writing within 30 days of conviction of any felony or of a misdemeanor involving lying, cheating, stealing, sexual offense, non-marijuana drug distribution, physical injury, or relating to the practice of the profession, regardless of jurisdiction.
Formulas to Know
Fall of a sloped drain and slope expressed as percent
Total fall = grade × run (1/8 in./ft × 32 ft = 4 in.; 90 ft at 1/4 in./ft = 22.5 in. vs 11.25 in. at 1/8 in./ft, a difference of 11-1/4 in.); Percent slope = (rise ÷ run) × 100 = (0.25 ÷ 12) × 100 = 2.08%Static / elevation pressure from height of water
Pressure (psi) = height in feet × 0.433 psi/ft (60 ft × 0.433 = 25.98 ≈ 26 psi; 40 ft = 17.3 psi; 15 ft = 6.5 psi)Pressure available to overcome pipe friction
Available psi = static pressure at meter − elevation loss (ft × 0.433) − meter loss − device losses − minimum residual pressure required at fixture (58 − 6.5 − 5 − 8 = 38.5 psi; 72 − 17.3 − 8 − 6 − 8 = 32.7 psi)Allowable friction loss rate per 100 feet
Rate = (available pressure ÷ total equivalent length) × 100 (24 psi / 150 ft → 16 psi/100 ft; 30 psi / 150 ft → 20 psi/100 ft; 26 psi / 175 ft → 14.86 psi/100 ft; 32.7 psi / 200 ft ≈ 16.4 psi/100 ft)Total equivalent length of a run
Equivalent length = developed length (sum of pipe segments, e.g., 8 + 5 + 12 = 25 ft) + equivalent length of fittings and valves (90 ft + 60 ft = 150 ft); where fitting sizes are unknown, add 50% of developed length (225 ft × 1.5 = 338 ft)Tank and pipe volume converted to gallons
Cylinder: V = π r² h (r = 2 ft, h = 6 ft → 75.4 cu ft; half height h = 3 ft → 37.7 cu ft); Cone: V = (π r² h) ÷ 3; Half-cylinder: V = (π r² L) ÷ 2; Rectangular: V = L × W × D (6 × 4 × 3.5 = 84 cu ft); Pipe: V = π r² × length with inches ÷ 12 first; then Gallons = cubic feet × 7.48BTU required to heat water
BTU = gallons × 8.33 lb/gal × temperature rise (°F) (30 gal × 8.33 × (140 − 45 = 95°F) = 23,740 BTU; 50 gal × 8.33 × 80°F = 33,320 BTU)Useful heat output and recovery time of a water heater
Useful output = input BTU/hr × efficiency (75,000 × 0.80 = 60,000 BTU/hr; 38,000 × 0.76 = 28,880 BTU/hr); Recovery time = BTU required ÷ useful output (33,320 ÷ 28,880 = 1.1538 hr × 60 = 69 minutes)Water heater capacity in gallons per hour
GPH = (input × efficiency) ÷ (8.33 lb/gal × temperature rise) (36,000 × 0.80 = 28,800 ÷ (8.33 × 60 = 499.8) = 57.6 GPH; 40,000 × 0.76 = 30,400 ÷ (8.33 × 92 = 766.36) = 39.7 GPH; 100,000 × 0.80 = 80,000 ÷ (8.33 × 70 = 583.1) = 137.1 GPH)Rolling offset — true offset and travel
True offset = √(set² + roll²) (√(12² + 9²) = 15.0 in.; √(14² + 10²) = 17.20 in.); Travel (45°) = true offset × 1.414 (15.0 × 1.414 = 21.2 in.; 17.20 × 1.414 = 24.33 in.); Travel (60°) = set × 1.155 (14 × 1.155 = 16.17 in.)