Building Envelope & Insulation Flashcards

What does R-value measure in building insulation?

Answer: Thermal resistance of a material

R-value measures a material's resistance to conductive heat flow; higher R-values indicate greater insulating effectiveness.

In cold climates, on which side of the wall assembly should a vapor retarder be installed?

Answer: On the warm-in-winter (interior) side of the insulation

In cold climates the vapor retarder belongs on the warm-in-winter interior side to prevent moisture-laden air from migrating to cold sheathing where it could condense.

Which insulation type has the highest R-value per inch of thickness?

Answer: Closed-cell spray polyurethane foam (ccSPF)

Closed-cell SPF achieves approximately R-6 to R-7 per inch, the highest of common insulation materials, due to its dense, low-conductivity cell structure.

What is the primary function of an air barrier in a building envelope?

Answer: To control bulk airflow through the building envelope

An air barrier controls the movement of bulk air through the envelope; this is distinct from a vapor retarder, which controls vapor diffusion.

What is thermal bridging in a building assembly?

Answer: Heat transfer through a high-conductivity element that bypasses the insulation layer

Thermal bridging occurs when a conductive material such as a wood stud or metal track creates a low-resistance path for heat to bypass the insulation in a wall or roof assembly.

In what order should air sealing and insulation work be performed during a retrofit?

Answer: Air seal all penetrations first, then install insulation

Air sealing must precede insulation installation because insulation covers and obscures gaps and penetrations that need to be sealed, making later access difficult or impossible.

Which insulation product is best suited for filling irregular cavities and existing wall cavities during a retrofit without removing interior finishes?

Answer: Dense-pack cellulose

Dense-pack cellulose can be blown into existing wall cavities through small drilled holes without requiring removal of interior finishes, making it ideal for retrofit applications.