Insulation and Ventilation Flashcards
7 cards from real INTERNACHI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Insulation and Ventilation flashcards as text
What is the primary purpose of a vapor retarder installed in a wall assembly?
Answer: To prevent moisture diffusion from warm to cold areas
A vapor retarder slows the movement of water vapor by diffusion from the warm, humid interior toward the cooler exterior where it could condense.
Which ventilation ratio is the InterNACHI-accepted standard for attic ventilation when no vapor retarder is present in the ceiling?
Answer: 1:150
Without a vapor retarder in the ceiling, the required net free ventilation area increases to 1 square foot per 150 square feet of attic floor area.
A home inspector observes fiberglass batt insulation installed without facing in a vented crawl space floor. What is the most likely concern?
Answer: Insulation will eventually fall due to lack of support and contact loss
Unfaced batts installed between floor joists in a crawl space typically sag and fall over time, losing contact with the subfloor and greatly reducing effectiveness.
What condition does the term 'thermal bypass' describe in an insulated building assembly?
Answer: Air movement around or through insulation reducing its effectiveness
A thermal bypass occurs when air moves through or around insulation, carrying heat with it and significantly degrading the assembly's overall thermal performance.
Which type of insulation is most appropriate for sealing small irregular gaps around pipes and wiring penetrations through top plates?
Answer: Two-component spray polyurethane foam
Two-component spray polyurethane foam expands to fill irregular shapes and adheres to most surfaces, making it ideal for air-sealing small penetrations.
In a cathedral ceiling with no attic space, what minimum ventilation channel depth is typically required between the roof deck and insulation?
Answer: 1 inch
Building codes and InterNACHI standards generally require a minimum 1-inch continuous air channel between the top of the insulation and the roof sheathing in cathedral ceiling assemblies.
A home inspector finds that bathroom exhaust fans are ducted into the attic and terminate without an outlet. What deficiency does this represent?
Answer: Moisture-laden air is being discharged into the attic, promoting mold and rot
Exhausting warm, moist bathroom air directly into the attic introduces significant moisture that can condense on structural members and sheathing, leading to mold, rot, and insulation damage.