CRC Building Codes & Standards 2 — Questions and Answers
Question 1: Under the International Residential Code (IRC), what is the minimum ceiling height required for habitable rooms?
- 6 feet 8 inches
- 7 feet 0 inches (Correct answer)
- 7 feet 6 inches
- 8 feet 0 inches
Correct answer: 7 feet 0 inches
The IRC requires a minimum ceiling height of 7 feet for habitable rooms in residential construction.
Question 2: Which code section governs the minimum stair tread depth for residential construction under the IRC?
- IRC R311.7.5.2 (Correct answer)
- IRC R302.1
- IRC R303.3
- IRC R308.4
Correct answer: IRC R311.7.5.2
IRC Section R311.7.5.2 specifies that residential stair treads must have a minimum depth of 10 inches.
Question 3: A homeowner wants to convert an unfinished basement into a bedroom. What is the minimum egress window opening required by the IRC?
- 4.0 square feet net clear opening
- 5.0 square feet net clear opening
- 5.7 square feet net clear opening (Correct answer)
- 6.0 square feet net clear opening
Correct answer: 5.7 square feet net clear opening
The IRC requires a minimum net clear opening of 5.7 square feet for basement sleeping room egress windows.
Question 4: Under the IRC, smoke alarms in new residential construction must be interconnected so that when one sounds, all sound. This requirement applies to homes with how many stories?
- Homes with 2 or more stories only
- All new residential construction (Correct answer)
- Only homes exceeding 3,000 square feet
- Homes with attached garages only
Correct answer: All new residential construction
The IRC requires interconnected smoke alarms in all new residential construction regardless of size or number of stories.
Question 5: What is the maximum slope allowed for a residential accessible route under the ADA/FHA guidelines when incorporated into IRC-compliant construction?
- 1:10 (10%)
- 1:12 (8.33%) (Correct answer)
- 1:16 (6.25%)
- 1:20 (5%)
Correct answer: 1:12 (8.33%)
Accessible ramps must not exceed a 1:12 slope (8.33%), meaning 1 inch of rise for every 12 inches of horizontal run.
Question 6: Under IRC provisions, what is the minimum R-value required for insulation in an exterior wall in a Climate Zone 5?
- R-13
- R-15
- R-20
- R-20 + R-5 continuous (Correct answer)
Correct answer: R-20 + R-5 continuous
Climate Zone 5 requires R-20 cavity insulation plus R-5 continuous insulation (or equivalent) in exterior walls per IRC energy provisions.
Question 7: A contractor is building a deck attached to a residence. Under the IRC, what is the minimum post size required for a freestanding deck post supporting a beam?
- 4x4 lumber (Correct answer)
- 4x6 lumber
- 6x6 lumber
- Determined solely by load calculations
Correct answer: 4x4 lumber
The IRC generally permits 4x4 posts for deck construction, though height and load may require larger sizes per prescriptive tables.
CRC Building Codes & Standards 2
Under the International Residential Code (IRC), what is the minimum ceiling height required for habitable rooms?