InterNACHI Insulation and Ventilation 4 — Questions and Answers
Question 1: What is the minimum recommended R-value for attic insulation in a Climate Zone 5 home, per DOE guidelines commonly referenced by InterNACHI?
- R-19
- R-30
- R-38
- R-49 (Correct answer)
Correct answer: R-49
The DOE recommends R-49 to R-60 for attics in Climate Zone 5, reflecting the need for high thermal resistance in colder northern climates.
Question 2: An inspector finds that recessed light fixtures in the ceiling below an attic are not IC-rated but are in direct contact with insulation. What is the hazard?
- Insulation will absorb light output reducing fixture efficiency
- Heat buildup from non-IC fixtures in contact with insulation can cause a fire (Correct answer)
- The insulation will off-gas toxic fumes when heated by the fixtures
- Non-IC fixtures will cause moisture condensation on insulation
Correct answer: Heat buildup from non-IC fixtures in contact with insulation can cause a fire
Non-IC-rated (Insulation Contact) fixtures are not designed to handle heat buildup when surrounded by insulation, creating a potential fire hazard.
Question 3: Which type of ventilation system uses negative pressure created by exhaust fans to draw fresh air through intentional or unintentional openings in the building envelope?
- Balanced ventilation
- Supply-only ventilation
- Exhaust-only ventilation (Correct answer)
- Energy recovery ventilation
Correct answer: Exhaust-only ventilation
Exhaust-only systems depressurize the building, drawing outdoor air in through leaks and intentional inlets to replace the exhausted air.
Question 4: What does a home inspector look for when evaluating whether blown-in cellulose insulation in an attic has settled significantly?
- Color change from gray to brown indicating moisture damage
- Depth ruler markings on attic trusses or joists indicating original fill depth (Correct answer)
- Surface crust indicating the insulation dried out after settling
- Presence of borate dust around the perimeter indicating movement
Correct answer: Depth ruler markings on attic trusses or joists indicating original fill depth
Depth rulers or markers installed at the time of insulation installation allow inspectors and homeowners to verify whether cellulose has settled below its original depth.
Question 5: A home inspector observes that a whole-house fan is installed in the ceiling but has no insulated cover in place during winter. What is the primary concern?
- The fan motor will be damaged by cold temperatures
- The large uninsulated opening allows significant heat loss and cold air infiltration (Correct answer)
- Fan blades will warp due to freezing condensation
- The opening creates a pathway for carbon monoxide to enter the attic
Correct answer: The large uninsulated opening allows significant heat loss and cold air infiltration
Whole-house fan openings represent a significant thermal and air-sealing weakness in winter; without an insulated cover, they allow substantial heat loss and cold infiltration.
Question 6: Which insulation material has the highest risk of moisture absorption and subsequent loss of R-value when exposed to water intrusion?
- Closed-cell spray foam
- Rigid extruded polystyrene (XPS)
- Fiberglass batts
- Open-cell spray foam (Correct answer)
Correct answer: Open-cell spray foam
Open-cell spray foam is highly permeable and will absorb water, losing its R-value and potentially harboring mold if exposed to moisture intrusion.
Question 7: What is the term for the phenomenon where warm interior air leaks into a wall or ceiling cavity and deposits moisture as it cools near the exterior surface?
- Vapor diffusion
- Air transport condensation (Correct answer)
- Interstitial condensation by diffusion
- Dew point deposition
Correct answer: Air transport condensation
Air transport condensation occurs when air-transported moisture — not diffusion — carries water vapor into a cavity where it condenses on cooler surfaces, often causing far more damage than vapor diffusion.
InterNACHI Insulation and Ventilation 4
What is the minimum recommended R-value for attic insulation in a Climate Zone 5 home, per DOE guidelines commonly referenced by InterNACHI?