What is the format? These ten original multiple-choice questions introduce Advanced IPC Design Practice — IPC 2021 study topics. They are practice material, not actual exam items. Official assessments may use different formats; check the current candidate guide for your credential.
What does this prepare me for? General code practice. Not aligned to any specific state exam blueprint. Check your licensing authority’s current bulletin. CodeReady does not confer a license.
What should I study? Start with drainage and venting design, water supply and storm, fixtures, equipment, and protection. This bank uses IPC 2021 (ICC); advanced design practice. Check the current exam objectives, adopted editions, and permitted references before planning your study.
How should I practice? Choose an answer before opening the explanation. Read the cited reference and revisit unfamiliar topics. These samples are general preparation, not jurisdiction-specific advice.
1 / Drainage and venting design
A sanitary stack serves eight branch intervals. Its total connected drainage fixture units fit the proposed diameter, but the load entering one branch interval exceeds that diameter's branch-interval limit. What is the correct design response?
- Average the overloaded interval with the seven lighter intervals
- Use only the building-sewer table to approve the stack
- Select a diameter that satisfies both the total-stack and single-branch-interval limits
- Approve the stack because its total load is within the limit
Show answer & explanation
Select a diameter that satisfies both the total-stack and single-branch-interval limits
For a stack with more than three branch intervals, Table 710.1(2) limits both the total stack load and the load into any one branch interval. Passing only the total-stack column is insufficient.
IPC 2021 Table 710.1(2)
2 / Fixtures, equipment, and protection
A hydromechanical grease interceptor is selected for a commercial kitchen. How must its grease-retention capacity relate to its flow-through rating?
- A fixed 10 pounds regardless of rated flow
- At least 2 gallons of grease for each connected drainage fixture unit
- At least 1 pound of grease for each 1 gpm of rated flow
- At least 2 pounds of grease for each 1 gpm of rated flow
Show answer & explanation
At least 2 pounds of grease for each 1 gpm of rated flow
Hydromechanical grease interceptors require grease-retention capacity of at least twice the flow-through rating when expressed as pounds and gallons per minute. A 25 gpm unit therefore requires at least 50 pounds of grease capacity.
IPC 2021 1003.3.5.1; Table 1003.3.5.1
3 / Drainage and venting design
A three-interval stack receives 80 DFU per interval. What is its minimum table diameter when all three intervals are loaded?
- 3 inches
- 6 inches
- 4 inches
- 5 inches
Show answer & explanation
4 inches
Total = 3 × 80 = 240 DFU. A 4-inch stack allows 240 total for three or fewer intervals and 90 per interval. Both 240 ≤ 240 and 80 ≤ 90 pass; the 3-inch total limit is only 48.
IPC 2021 Table 710.1(2)
4 / Drainage and venting design
A contractor voluntarily installs a 6-inch branch where Table 710.1(2) requires only 4 inches. Its individual vent is 30 feet long. What drain diameter is used for the half-size vent calculation?
- The required 4-inch drain diameter
- The voluntarily installed 6-inch diameter in every case
- The sum of all trap outlet diameters
- The diameter of the water service
Show answer & explanation
The required 4-inch drain diameter
Section 906.2 bases this calculation on required drain size. Half of 4 is 4 ÷ 2 = 2 inches; the 30-foot length does not trigger the increase for lengths exceeding 40 feet. Other applicable vent provisions still apply.
IPC 2021 906.2
5 / Drainage and venting design
A project has twelve eligible fixtures on interconnected circuit-vented branches. What is the minimum number of separately compliant circuit-vent groups needed?
- Twelve
- Two
- Three
- One
Show answer & explanation
Two
Each circuit-vent group may have at most eight fixtures. The minimum number is ceiling(12 ÷ 8) = 2. Interconnecting the branches does not turn twelve fixtures into one permitted group.
IPC 2021 914.1.1
6 / Water supply and storm
A test loop loses 9 psi at 18 gpm. Assume loss varies exactly with flow squared over the range studied. What flow corresponds to a 16-psi loss?
- 27 gpm
- 24 gpm
- 21 gpm
- 32 gpm
Show answer & explanation
24 gpm
Q2 = 18 × sqrt(16 ÷ 9) = 18 × 4/3 = 24 gpm. The square-law relation is a stated model, not a universal IPC conversion or a substitute for actual component data.
IPC 2021 604.1 (context); Trade math, supplied square-law loss
7 / Water supply and storm
An architectural leader carries 180 gpm and must have a rectangular section. Which listed shape is adequate without moving to a larger capacity row?
- 2-1/2 by 3 inches
- 2 by 2 inches
- 2 by 4 inches
- 3 by 4-1/4 inches
Show answer & explanation
3 by 4-1/4 inches
The 3 by 4-1/4-inch leader is rated 192 gpm, giving 192 - 180 = 12 gpm margin. The smaller listed options are in 30- or 92-gpm rows and cannot carry 180 gpm.
IPC 2021 Table 1106.3
8 / Water supply and storm
A rectangular gutter 3 by 5 inches is proposed for 180 gpm. Which listed slope supplies adequate capacity?
- 1/4 inch per foot
- 1/8 inch per foot based on this row
- 1/2 inch per foot
- Level installation based on this row
Show answer & explanation
1/2 inch per foot
The 3-by-5 row permits 157 gpm at 1/4 inch per foot and 225 at 1/2. Since 180 > 157 and 180 ≤ 225, the listed adequate slope is 1/2 inch per foot. Do not infer unlisted flatter capacities.
IPC 2021 Table 1106.6
9 / Fixtures, equipment, and protection
A 3/4-inch relief outlet uses insert-fitting discharge tubing, with nominal sizes 3/4, 1 and 1-1/4 inches available. What minimum tubing size and minimum termination clearance above the receptor rim follow the stated rules?
- 1-1/4-inch tubing and 6-inch minimum clearance
- 1-inch tubing and 2-inch clearance
- 3/4-inch tubing and 1-1/2-inch clearance
- 1-inch tubing and 1-inch clearance
Show answer & explanation
1-inch tubing and 2-inch clearance
Insert fittings require one nominal size larger: 3/4 to 1 inch. Minimum termination clearance is twice the discharge diameter: 2 × 1 = 2 inches. The separate 6-inch maximum, fastening and all other discharge requirements still apply.
IPC 2021 504.6
10 / Fixtures, equipment, and protection
An RP assembly protects a continuously pressurized process connection. A reviewer rejects it solely because pressure is continuous. Is that reason supported by the installation provision?
- No; continuous pressure is permitted, with compliant relief drainage and installation
- No; because RP relief ports may be capped
- Yes; every backflow preventer must depressurize after each use
- Yes; only atmospheric vacuum breakers permit continuous pressure
Show answer & explanation
No; continuous pressure is permitted, with compliant relief drainage and installation
Section 608.14.2 expressly permits RP assemblies under continuous pressure. The permission does not waive the relief-opening air gap, protection from submergence, listing or other applicable installation conditions.
IPC 2021 608.14.2