Insulation and Ventilation Flashcards

What does R-value measure in building insulation?

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.

Which older insulation material may contain asbestos and should be flagged as a potential health hazard during inspection?

Answer: Vermiculite insulation

Vermiculite from Libby, Montana was contaminated with asbestos and poses a health risk if disturbed; inspectors should recommend professional testing.

What is the primary purpose of a vapor barrier installed on a crawl space floor?

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.

What is the minimum recommended attic ventilation ratio when a vapor retarder is present?

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.

Which type of insulation expands upon application to fill gaps and create an effective air seal?

Answer: Spray polyurethane foam (SPF)

Spray polyurethane foam expands after application to seal gaps, cracks, and voids, providing both thermal insulation and air sealing.

What is the primary function of soffit vents in an attic ventilation system?

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.

What building science phenomenon causes warm, moist interior air to rise and accumulate in the attic?

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.