Building Envelope & Insulation Flashcards

Which insulation material has the highest R-value per inch?

Answer: Closed-cell spray foam

Closed-cell spray foam provides approximately R-6 to R-7 per inch, the highest among common insulation materials.

In RESNET standards, what is the primary purpose of a blower door test for the building envelope?

Answer: Quantify air leakage through the building shell

A blower door test depressurizes the home to measure air leakage (ACH50 or CFM50) through the building shell.

What does ACH50 measure in residential energy testing?

Answer: Air changes per hour at 50 Pascals pressure difference

ACH50 is the number of air changes per hour measured when the home is pressurized or depressurized to 50 Pascals.

When insulating a cathedral ceiling without a vented air space, which approach is code-compliant?

Answer: Unvented assembly using air-impermeable insulation meeting IRC requirements

Unvented cathedral ceilings require air-impermeable insulation (such as spray foam) meeting minimum R-value requirements per IRC Table R806.5.

What is thermal bridging in a wall assembly?

Answer: Heat transfer through a conductive element bypassing insulation

Thermal bridging occurs when a conductive material (like wood studs or steel framing) creates a path for heat to bypass the insulation layer.

Which wall framing strategy best reduces thermal bridging compared to standard 2x4 construction?

Answer: Advanced framing (OVE) with continuous exterior insulation

Advanced framing combined with continuous exterior insulation minimizes framing fraction and eliminates thermal bridges through the wall assembly.

Where should the vapor retarder be located in a cold climate wall assembly?

Answer: On the warm-in-winter side of the insulation

In cold climates, the vapor retarder belongs on the interior (warm-in-winter) side to prevent moisture-laden indoor air from diffusing into and condensing within the wall cavity.