CT Sheet Metal Contractor Exam
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A| Instant Download Pdf
1. Which gauge of steel is thicker?
A) 20 gauge
B) 24 gauge
C) 28 gauge
D) 30 gauge
A) 20 gauge
Thicker metals have lower gauge numbers; 20 gauge is thicker than
24, 28, or 30.
2. What is the primary purpose of a duct liner?
A) Structural support
B) Thermal insulation
C) Decorative finish
D) Fireproofing
B) Thermal insulation
Duct liners reduce heat loss/gain and can improve acoustic
performance.
3. When installing sheet metal ducts, what is the maximum recommended
spacing for support hangers?
A) 2 feet
B) 4 feet
C) 6 feet
D) 10 feet
C) 6 feet
Support hangers are typically spaced 4–6 feet apart to prevent
sagging.
,4. What type of joint is commonly used in rectangular ductwork?
A) Lap joint
B) Butt joint
C) Flanged seam
D) Dovetail joint
C) Flanged seam
Flanged seams allow secure connections and easier assembly for
rectangular ducts.
5. What is the purpose of a backdraft damper in ductwork?
A) Prevent air leakage
B) Regulate airflow direction
C) Prevent reverse airflow
D) Increase system pressure
C) Prevent reverse airflow
Backdraft dampers allow airflow in one direction and block airflow
in the opposite direction.
6. Which tool is used to measure duct diameter?
A) Micrometer
B) Caliper
C) Tape measure
D) Protractor
B) Caliper
Calipers provide accurate measurement of duct diameter for proper
fitting.
7. What is the most common material for sheet metal duct fabrication?
A) Aluminum
B) Stainless steel
C) Galvanized steel
D) Copper
C) Galvanized steel
Galvanized steel is widely used because it resists corrosion and is
cost-effective.
8. What is the main advantage of spiral ductwork over rectangular
ductwork?
A) Easier installation
B) Higher friction loss
C) Better aesthetics
, D) Less material cost
A) Easier installation
Spiral ducts are easier to install and produce less leakage compared
to rectangular ducts.
9. Which type of HVAC insulation is commonly used on ductwork?
A) Fiberglass
B) Foam
C) Mineral wool
D) All of the above
D) All of the above
Fiberglass, foam, and mineral wool are all commonly used depending
on thermal and acoustic needs.
10. What is the purpose of a takeoff in sheet metal duct fabrication?
A) Connecting multiple ducts
B) Measuring airflow
C) Transitioning duct sizes
D) Removing debris
C) Transitioning duct sizes
A takeoff allows air to branch from a main duct to a secondary duct.
11. What is the recommended method for cutting sheet metal?
A) Shears
B) Saw
C) Laser
D) Sandpaper
A) Shears
Sheet metal shears provide clean, straight cuts suitable for ductwork.
12. What type of fire rating is required for ductwork in commercial
buildings?
A) 30 minutes
B) 1 hour
C) 2 hours
D) 4 hours
B) 1 hour
Many commercial codes require ducts penetrating fire-rated
assemblies to have at least a 1-hour fire rating.
13. What is the minimum distance a duct should be from electrical
wiring?
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A| Instant Download Pdf
1. Which gauge of steel is thicker?
A) 20 gauge
B) 24 gauge
C) 28 gauge
D) 30 gauge
A) 20 gauge
Thicker metals have lower gauge numbers; 20 gauge is thicker than
24, 28, or 30.
2. What is the primary purpose of a duct liner?
A) Structural support
B) Thermal insulation
C) Decorative finish
D) Fireproofing
B) Thermal insulation
Duct liners reduce heat loss/gain and can improve acoustic
performance.
3. When installing sheet metal ducts, what is the maximum recommended
spacing for support hangers?
A) 2 feet
B) 4 feet
C) 6 feet
D) 10 feet
C) 6 feet
Support hangers are typically spaced 4–6 feet apart to prevent
sagging.
,4. What type of joint is commonly used in rectangular ductwork?
A) Lap joint
B) Butt joint
C) Flanged seam
D) Dovetail joint
C) Flanged seam
Flanged seams allow secure connections and easier assembly for
rectangular ducts.
5. What is the purpose of a backdraft damper in ductwork?
A) Prevent air leakage
B) Regulate airflow direction
C) Prevent reverse airflow
D) Increase system pressure
C) Prevent reverse airflow
Backdraft dampers allow airflow in one direction and block airflow
in the opposite direction.
6. Which tool is used to measure duct diameter?
A) Micrometer
B) Caliper
C) Tape measure
D) Protractor
B) Caliper
Calipers provide accurate measurement of duct diameter for proper
fitting.
7. What is the most common material for sheet metal duct fabrication?
A) Aluminum
B) Stainless steel
C) Galvanized steel
D) Copper
C) Galvanized steel
Galvanized steel is widely used because it resists corrosion and is
cost-effective.
8. What is the main advantage of spiral ductwork over rectangular
ductwork?
A) Easier installation
B) Higher friction loss
C) Better aesthetics
, D) Less material cost
A) Easier installation
Spiral ducts are easier to install and produce less leakage compared
to rectangular ducts.
9. Which type of HVAC insulation is commonly used on ductwork?
A) Fiberglass
B) Foam
C) Mineral wool
D) All of the above
D) All of the above
Fiberglass, foam, and mineral wool are all commonly used depending
on thermal and acoustic needs.
10. What is the purpose of a takeoff in sheet metal duct fabrication?
A) Connecting multiple ducts
B) Measuring airflow
C) Transitioning duct sizes
D) Removing debris
C) Transitioning duct sizes
A takeoff allows air to branch from a main duct to a secondary duct.
11. What is the recommended method for cutting sheet metal?
A) Shears
B) Saw
C) Laser
D) Sandpaper
A) Shears
Sheet metal shears provide clean, straight cuts suitable for ductwork.
12. What type of fire rating is required for ductwork in commercial
buildings?
A) 30 minutes
B) 1 hour
C) 2 hours
D) 4 hours
B) 1 hour
Many commercial codes require ducts penetrating fire-rated
assemblies to have at least a 1-hour fire rating.
13. What is the minimum distance a duct should be from electrical
wiring?
