NHIE Insulation and Ventilation 1 — Questions and Answers
Question 1: What does R-value measure in building insulation?
- The density of the insulation material
- The thermal resistance of insulation to heat flow (Correct answer)
- The moisture permeability of insulation
- The fire resistance rating of insulation
Correct answer: The thermal resistance of insulation to heat flow
R-value measures thermal resistance — the higher the R-value, the greater the insulation's resistance to heat flow through it.
Question 2: Which older insulation material may contain asbestos and should be flagged as a potential health hazard during inspection?
- Fiberglass batt insulation
- Mineral wool (rock wool) insulation
- Vermiculite insulation (Correct answer)
- Cellulose insulation
Correct answer: Vermiculite insulation
Vermiculite from Libby, Montana was contaminated with asbestos and poses a health risk if disturbed; inspectors should recommend professional testing.
Question 3: What is the primary purpose of a vapor barrier installed on a crawl space floor?
- To prevent structural damage from flooding
- To reduce soil moisture from migrating into the crawl space (Correct answer)
- To improve air circulation under the floor
- To prevent pest infiltration
Correct answer: To reduce soil moisture from migrating into the crawl space
A ground cover vapor barrier reduces moisture evaporation from soil into the crawl space, preventing condensation and wood damage.
Question 4: What is the minimum recommended attic ventilation ratio when a vapor retarder is present?
- 1:150
- 1:300 (Correct answer)
- 1:450
- 1:600
Correct answer: 1:300
Building codes typically require 1 square foot of net free ventilation area per 300 square feet of attic floor when a vapor retarder is used.
Question 5: Which type of insulation expands upon application to fill gaps and create an effective air seal?
- Fiberglass batts
- Mineral wool batts
- Spray polyurethane foam (SPF) (Correct answer)
- Blown-in cellulose
Correct answer: Spray polyurethane foam (SPF)
Spray polyurethane foam expands after application to seal gaps, cracks, and voids, providing both thermal insulation and air sealing.
Question 6: What is the primary function of soffit vents in an attic ventilation system?
- To exhaust hot air from the attic peak
- To allow cool air to enter at the eaves and flow upward through the attic (Correct answer)
- To reduce moisture accumulation in exterior wall cavities
- To provide access points for pest control treatments
Correct answer: To allow cool air to enter at the eaves and flow upward through the attic
Soffit vents serve as intake vents at the lowest point of the attic, allowing cooler outside air to flow in and push warm air toward ridge or exhaust vents.
Question 7: What building science phenomenon causes warm, moist interior air to rise and accumulate in the attic?
- Thermal bridging
- The stack effect (Correct answer)
- Convective looping
- Vapor diffusion
Correct answer: The stack effect
The stack effect describes buoyancy-driven air movement where warm interior air rises and exits at high points, drawing replacement air in at lower openings.
NHIE Insulation and Ventilation 1
What does R-value measure in building insulation?