CSLB Class B General Contractor's
License - Building's Exam: Core
Trades 2025 With 100% Correct
Answers
3 inches - CORRECT ANSWER✔✔What is the minimum drain pipe size for the toilet in a
residential home?
B) Fire protection contractor - CORRECT ANSWER✔✔Who is licensed to install residential fire
sprinkler systems?
A) Plumbing contractor
B) Fire protection contractor
C) General Building contractor
D) Pipeline contractor
C) Clean the surface using a power tool - CORRECT ANSWER✔✔When brazing or soldering gas
pipes during the installation of water heaters, what is the best way to prepare the pipe?
A) Clean it with water
B) Blow into the pipe using your lungs
C) Clean the surface using a power tool
D) Use a pressurized air canister
D) Endless rope lift - CORRECT ANSWER✔✔Which personal lift is not acceptable?
,A) Scissor
B) Boom
C) Manual
D) Endless rope lift
B) To soften PVC pipe before applying PVC cement - CORRECT ANSWER✔✔What is the purpose
of PVC primer?
A) To glue PVC pipes to other materials
B) To soften PVC pipe before applying PVC cement
C) To prevent electrical shock
D) To help solder conduit or piping
C) Flashing
(Leaks are most common when two surfaces meet or around fenestration. Leaks are most
prominent in valley flashing and improperly installed window flashing.) - CORRECT
ANSWER✔✔What is the most common location to find a roof leak?
A) Attic
B) Shingles
C) Flashing
D) Collar tie
C) Pipe supports come into contact with metal piping
,(Mainly due to water hammer.) - CORRECT ANSWER✔✔What is the most common reason for
noise in piping when a water fixture is turned on or off?
A) Hot water was used
B) Cold water was used
C) Pipe supports come into contact with metal piping
D) The walls are not up to code causing pipe failure
C) Brass type - CORRECT ANSWER✔✔If you send your employee to purchase a 2-inch water
supply valve and they return with a 1.5-inch supply valve, then what is the proper composition
of the valve?
A) The casing must be made of plastic
B) The employee must return and purchase a wrought iron valve
C) Brass type
D) The connection must be silver and body made of iron
10 - CORRECT ANSWER✔✔When penetrating a roof with an exhaust, the exhaust must be no
closer than _____ feet to any air intake or openable window.
A) Class A - CORRECT ANSWER✔✔Which roof assembly has the best fire rating?
A) Class A
B) Class B
C) Class I
D) Class III
, D) Use of materials that are compatible with the type of pipe and fitting materials - CORRECT
ANSWER✔✔What does material compatibility refer to when installing alternate water sources
in existing plumbing systems?
A) Plumbing fixtures have to come from the same manufacturer
B) Only the couplings must be made of metal
C) All plumbing connections must be soldered or brazed
D) Use of materials that are compatible with the type of pipe and fitting materials
C) Weather seal, weather strip, and apply caulking - CORRECT ANSWER✔✔When you have a
gap in the building envelope, what do you do to prevent air leakage?
A) Stuff insulation into gaps
B) Put caulking in and around the gaps
C) Weather seal, weather strip, and apply caulking
D) Nothing, all buildings require air leakage
18 inches - CORRECT ANSWER✔✔In order to protect a water heater from damage, what is the
minimum height it should be from the floor of a garage?
4
(According to the California Plumbing Code, the vertical piping between two consecutive inlet
levels shall be considered a wet-vented section. Each wet-vented section shall be not less than
one pipe size exceeding the required minimum waste pipe size of the upper fixture or shall be
one pipe size exceeding the required minimum pipe size for the sum of the fixture units served
by such wet-vented section, whichever is larger, but no case less than 2 inches.) - CORRECT
ANSWER✔✔How many plumbing fixtures can be vented by a single vertical wet-vent?
License - Building's Exam: Core
Trades 2025 With 100% Correct
Answers
3 inches - CORRECT ANSWER✔✔What is the minimum drain pipe size for the toilet in a
residential home?
B) Fire protection contractor - CORRECT ANSWER✔✔Who is licensed to install residential fire
sprinkler systems?
A) Plumbing contractor
B) Fire protection contractor
C) General Building contractor
D) Pipeline contractor
C) Clean the surface using a power tool - CORRECT ANSWER✔✔When brazing or soldering gas
pipes during the installation of water heaters, what is the best way to prepare the pipe?
A) Clean it with water
B) Blow into the pipe using your lungs
C) Clean the surface using a power tool
D) Use a pressurized air canister
D) Endless rope lift - CORRECT ANSWER✔✔Which personal lift is not acceptable?
,A) Scissor
B) Boom
C) Manual
D) Endless rope lift
B) To soften PVC pipe before applying PVC cement - CORRECT ANSWER✔✔What is the purpose
of PVC primer?
A) To glue PVC pipes to other materials
B) To soften PVC pipe before applying PVC cement
C) To prevent electrical shock
D) To help solder conduit or piping
C) Flashing
(Leaks are most common when two surfaces meet or around fenestration. Leaks are most
prominent in valley flashing and improperly installed window flashing.) - CORRECT
ANSWER✔✔What is the most common location to find a roof leak?
A) Attic
B) Shingles
C) Flashing
D) Collar tie
C) Pipe supports come into contact with metal piping
,(Mainly due to water hammer.) - CORRECT ANSWER✔✔What is the most common reason for
noise in piping when a water fixture is turned on or off?
A) Hot water was used
B) Cold water was used
C) Pipe supports come into contact with metal piping
D) The walls are not up to code causing pipe failure
C) Brass type - CORRECT ANSWER✔✔If you send your employee to purchase a 2-inch water
supply valve and they return with a 1.5-inch supply valve, then what is the proper composition
of the valve?
A) The casing must be made of plastic
B) The employee must return and purchase a wrought iron valve
C) Brass type
D) The connection must be silver and body made of iron
10 - CORRECT ANSWER✔✔When penetrating a roof with an exhaust, the exhaust must be no
closer than _____ feet to any air intake or openable window.
A) Class A - CORRECT ANSWER✔✔Which roof assembly has the best fire rating?
A) Class A
B) Class B
C) Class I
D) Class III
, D) Use of materials that are compatible with the type of pipe and fitting materials - CORRECT
ANSWER✔✔What does material compatibility refer to when installing alternate water sources
in existing plumbing systems?
A) Plumbing fixtures have to come from the same manufacturer
B) Only the couplings must be made of metal
C) All plumbing connections must be soldered or brazed
D) Use of materials that are compatible with the type of pipe and fitting materials
C) Weather seal, weather strip, and apply caulking - CORRECT ANSWER✔✔When you have a
gap in the building envelope, what do you do to prevent air leakage?
A) Stuff insulation into gaps
B) Put caulking in and around the gaps
C) Weather seal, weather strip, and apply caulking
D) Nothing, all buildings require air leakage
18 inches - CORRECT ANSWER✔✔In order to protect a water heater from damage, what is the
minimum height it should be from the floor of a garage?
4
(According to the California Plumbing Code, the vertical piping between two consecutive inlet
levels shall be considered a wet-vented section. Each wet-vented section shall be not less than
one pipe size exceeding the required minimum waste pipe size of the upper fixture or shall be
one pipe size exceeding the required minimum pipe size for the sum of the fixture units served
by such wet-vented section, whichever is larger, but no case less than 2 inches.) - CORRECT
ANSWER✔✔How many plumbing fixtures can be vented by a single vertical wet-vent?
