CRC Materials & Equipment Knowledge 2 — Questions and Answers
Question 1: What is the minimum compressive strength of concrete typically specified for residential foundations in most US building codes?
- 1,500 psi
- 2,500 psi (Correct answer)
- 3,500 psi
- 5,000 psi
Correct answer: 2,500 psi
Residential foundation concrete is typically specified at a minimum of 2,500 psi compressive strength per most US building codes.
Question 2: Which type of lumber grade stamp marking indicates the moisture content of the wood at the time of surfacing?
- S-GRN
- MC-15
- KD-19 (Correct answer)
- HT
Correct answer: KD-19
KD-19 stamped on lumber means it was kiln-dried to a maximum moisture content of 19% at the time of surfacing.
Question 3: What is the standard width of a residential interior door rough opening when the door unit is 32 inches wide?
- 32 inches
- 33 inches
- 34 inches (Correct answer)
- 36 inches
Correct answer: 34 inches
A 32-inch door typically requires a 34-inch rough opening to allow for the frame, shimming, and installation clearance.
Question 4: Which insulation material has the highest R-value per inch of thickness?
- Fiberglass batt
- Cellulose
- Closed-cell spray foam (Correct answer)
- Mineral wool
Correct answer: Closed-cell spray foam
Closed-cell spray polyurethane foam provides approximately R-6 to R-7 per inch, the highest of common residential insulation materials.
Question 5: What does the term 'vapor retarder' Class I refer to in residential construction?
- A material with a perm rating greater than 10
- A material with a perm rating of 0.1 or less (Correct answer)
- A material with a perm rating between 1 and 10
- A material with a perm rating between 0.1 and 1
Correct answer: A material with a perm rating of 0.1 or less
Class I vapor retarders have a perm rating of 0.1 or less, making them the most effective at resisting moisture vapor transmission.
Question 6: Which type of roofing underlayment is required directly beneath metal roofing panels on a residential structure?
- Standard #15 felt
- Ice and water shield
- Synthetic non-perforated underlayment (Correct answer)
- No underlayment is required for metal roofs
Correct answer: Synthetic non-perforated underlayment
A non-perforated synthetic underlayment or appropriate felt is required under metal roofing panels to prevent moisture infiltration and reduce condensation.
Question 7: What is the purpose of a weep screed at the base of an exterior stucco application?
- To anchor the stucco to the framing
- To allow moisture trapped behind the stucco to drain out (Correct answer)
- To provide a decorative reveal at the foundation line
- To act as a control joint preventing cracking
Correct answer: To allow moisture trapped behind the stucco to drain out
A weep screed is installed at the base of stucco systems to allow any water that infiltrates behind the stucco to drain out and not accumulate.
CRC Materials & Equipment Knowledge 2
What is the minimum compressive strength of concrete typically specified for residential foundations in most US building codes?