PLUMBER’S EXAM | INTERIOR DESIGN PROFESSIONAL EXAM
2026/2027 LATEST UPDATE | QUESTIONS AND VERIFIED ANSWERS
| GRADED A+
When is a plumbing permit required? -
CORRECT|ANSWER
For any system construction, removal, or repair (full system)
What are the 3 categories of inspection? -
CORRECT|ANSWER
1. Rough-in (underground): buried piping
2. Middle rough-in: before drywall (sanitary, storm, and water)
3. Final: all fixtures are in and ready to be used
Is a permit required to fix a leak? -
CORRECT|ANSWER
Nope, but you still have to follow code
Can a homeowner do his/her own installation? -
CORRECT|ANSWER
No, you have to have a licensed plumber in NC for system work
What are the 3 basic parts of the plumbing system? -
CORRECT|ANSWER
Supply, Drain, Fixtures
What are the 3 classes of pipe in a drainage system? -
CORRECT|ANSWER
Drain (waste), Traps, Vents
What are the 3 basic outdoor plumbing combos? -
CORRECT|ANSWER
, City H20 + City Sewer ( no new infrastructure)
Well + Septic (homeowner, 'off-grid')
City H20 + Septic (water is easier to install than sewer)
What is an isometric plumbing drawing?
What angle does it meet at?
What is another name for this type of drawing? -
CORRECT|ANSWER
A 3D representation of pipes, fittings and fixtures on a 2D platform.
120degrees.
Riser diagram.
How much is 1 F.U. Value? -
CORRECT|ANSWER
7.5 gal/min
1 cubic foot
What is the minimum fall/foot? -
CORRECT|ANSWER
1/4in per 1ft (horizontal pipes)
What's the difference between a drain pipe and a waste line? -
CORRECT|ANSWER
Drain: organic waste
Waste line: liquid waste
What is the minimum size for a building drain?
When is this not the case? -
CORRECT|ANSWER
3"
When you have more than 2 water closets, it becomes 4"
2026/2027 LATEST UPDATE | QUESTIONS AND VERIFIED ANSWERS
| GRADED A+
When is a plumbing permit required? -
CORRECT|ANSWER
For any system construction, removal, or repair (full system)
What are the 3 categories of inspection? -
CORRECT|ANSWER
1. Rough-in (underground): buried piping
2. Middle rough-in: before drywall (sanitary, storm, and water)
3. Final: all fixtures are in and ready to be used
Is a permit required to fix a leak? -
CORRECT|ANSWER
Nope, but you still have to follow code
Can a homeowner do his/her own installation? -
CORRECT|ANSWER
No, you have to have a licensed plumber in NC for system work
What are the 3 basic parts of the plumbing system? -
CORRECT|ANSWER
Supply, Drain, Fixtures
What are the 3 classes of pipe in a drainage system? -
CORRECT|ANSWER
Drain (waste), Traps, Vents
What are the 3 basic outdoor plumbing combos? -
CORRECT|ANSWER
, City H20 + City Sewer ( no new infrastructure)
Well + Septic (homeowner, 'off-grid')
City H20 + Septic (water is easier to install than sewer)
What is an isometric plumbing drawing?
What angle does it meet at?
What is another name for this type of drawing? -
CORRECT|ANSWER
A 3D representation of pipes, fittings and fixtures on a 2D platform.
120degrees.
Riser diagram.
How much is 1 F.U. Value? -
CORRECT|ANSWER
7.5 gal/min
1 cubic foot
What is the minimum fall/foot? -
CORRECT|ANSWER
1/4in per 1ft (horizontal pipes)
What's the difference between a drain pipe and a waste line? -
CORRECT|ANSWER
Drain: organic waste
Waste line: liquid waste
What is the minimum size for a building drain?
When is this not the case? -
CORRECT|ANSWER
3"
When you have more than 2 water closets, it becomes 4"
