CO Class C Residential Contractor Exam
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A| Instant Download Pdf
1. What type of construction is generally covered under a Colorado Class C
Residential Contractor license?
A. High-rise commercial buildings
B. Industrial structures
C. Multi-family buildings over 3 stories
D. One- and two-family dwellings and townhouses up to 3 stories
Rationale: Class C focuses on low-rise residential structures, not
commercial or industrial buildings.
2. Which code primarily governs the construction of one- and two-family
dwellings in Colorado?
A. IBC
B. IRC
C. IPC
D. IMC
Rationale: The International Residential Code (IRC) is adopted for
residential structures of Class C scope.
3. What is the minimum required ceiling height for habitable rooms per IRC?
A. 6'4"
,B. 6'6"
C. 7'0" D. 8'0"
Rationale: IRC requires 7 feet minimum in habitable spaces except limited
sloped-ceiling allowances.
4. Which document is required before beginning any residential construction
project?
A. Inspection log
B. Subcontractor schedule
C. Building permit
D. Structural shop drawings
Rationale: A building permit must be issued prior to any construction
activity.
5. Footings in Colorado must extend below what?
A. 6 inches underground
B. Finished floor level
C. Insulation barrier
D. Frost line
Rationale: Footings must bear below frost depth to prevent movement and
structural damage.
6. When is a vapor barrier generally required under slabs in residential
construction?
A. Only for commercial structures
B. Only in warm climates
C. Under most concrete slabs-on-grade
D. Never required
, Rationale: IRC mandates vapor barriers beneath slabs to reduce moisture
migration.
7. What is the standard minimum compressive strength for residential
concrete footings?
A. 1,000 psi
B. 1,500 psi
C. 2,500 psi
D. 4,000 psi
Rationale: Most IRC residential footings use 2,500 psi concrete unless
engineered otherwise.
8. The minimum slope for drainage away from a foundation is:
A. 1%
B. 5%
C. 10%
D. 15%
Rationale: IRC requires a 6-inch drop in the first 10 feet, equal to roughly
5%.
9. What is the minimum width for a standard residential stairway?
A. 28 inches
B. 30 inches
C. 36 inches
D. 40 inches
Rationale: IRC sets 36 inches minimum clear width for residential stairs.
10. Maximum riser height for residential stairs is:
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A| Instant Download Pdf
1. What type of construction is generally covered under a Colorado Class C
Residential Contractor license?
A. High-rise commercial buildings
B. Industrial structures
C. Multi-family buildings over 3 stories
D. One- and two-family dwellings and townhouses up to 3 stories
Rationale: Class C focuses on low-rise residential structures, not
commercial or industrial buildings.
2. Which code primarily governs the construction of one- and two-family
dwellings in Colorado?
A. IBC
B. IRC
C. IPC
D. IMC
Rationale: The International Residential Code (IRC) is adopted for
residential structures of Class C scope.
3. What is the minimum required ceiling height for habitable rooms per IRC?
A. 6'4"
,B. 6'6"
C. 7'0" D. 8'0"
Rationale: IRC requires 7 feet minimum in habitable spaces except limited
sloped-ceiling allowances.
4. Which document is required before beginning any residential construction
project?
A. Inspection log
B. Subcontractor schedule
C. Building permit
D. Structural shop drawings
Rationale: A building permit must be issued prior to any construction
activity.
5. Footings in Colorado must extend below what?
A. 6 inches underground
B. Finished floor level
C. Insulation barrier
D. Frost line
Rationale: Footings must bear below frost depth to prevent movement and
structural damage.
6. When is a vapor barrier generally required under slabs in residential
construction?
A. Only for commercial structures
B. Only in warm climates
C. Under most concrete slabs-on-grade
D. Never required
, Rationale: IRC mandates vapor barriers beneath slabs to reduce moisture
migration.
7. What is the standard minimum compressive strength for residential
concrete footings?
A. 1,000 psi
B. 1,500 psi
C. 2,500 psi
D. 4,000 psi
Rationale: Most IRC residential footings use 2,500 psi concrete unless
engineered otherwise.
8. The minimum slope for drainage away from a foundation is:
A. 1%
B. 5%
C. 10%
D. 15%
Rationale: IRC requires a 6-inch drop in the first 10 feet, equal to roughly
5%.
9. What is the minimum width for a standard residential stairway?
A. 28 inches
B. 30 inches
C. 36 inches
D. 40 inches
Rationale: IRC sets 36 inches minimum clear width for residential stairs.
10. Maximum riser height for residential stairs is:
