BAP Building Envelope & Insulation 1 — Questions and Answers
Question 1: What does R-value measure in building insulation?
- Thermal resistance of a material (Correct answer)
- Rate of air infiltration through a material
- Reflectivity of a surface to radiant heat
- Rate of moisture vapor absorption
Correct answer: Thermal resistance of a material
R-value measures a material's resistance to conductive heat flow; higher R-values indicate greater insulating effectiveness.
Question 2: In cold climates, on which side of the wall assembly should a vapor retarder be installed?
- On the exterior side of the wall cavity
- On the warm-in-winter (interior) side of the insulation (Correct answer)
- In the middle of the insulation layer
- On the exterior sheathing, behind the cladding
Correct 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.
Question 3: Which insulation type has the highest R-value per inch of thickness?
- Fiberglass batt
- Blown cellulose
- Closed-cell spray polyurethane foam (ccSPF) (Correct answer)
- Mineral wool batt
Correct 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.
Question 4: What is the primary function of an air barrier in a building envelope?
- To prevent moisture vapor diffusion through wall assemblies
- To control bulk airflow through the building envelope (Correct answer)
- To reflect radiant heat from exterior surfaces
- To increase the overall R-value of wall assemblies
Correct 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.
Question 5: What is thermal bridging in a building assembly?
- Heat transfer through a high-conductivity element that bypasses the insulation layer (Correct answer)
- A method for connecting insulation panels across framing members
- Measurement of heat loss through fenestration products
- A heat-exchange process between supply and return air streams
Correct 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.
Question 6: In what order should air sealing and insulation work be performed during a retrofit?
- Insulate first, then air seal over the insulation
- Air seal all penetrations first, then install insulation (Correct answer)
- Either order is acceptable — there is no required sequence
- Insulate, then air seal, then add a second insulation layer on top
Correct 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.
Question 7: Which insulation product is best suited for filling irregular cavities and existing wall cavities during a retrofit without removing interior finishes?
- Fiberglass batts cut to fit
- Rigid foam boards
- Dense-pack cellulose (Correct answer)
- Structural insulated panels (SIPs)
Correct 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.
BAP Building Envelope & Insulation 1
What does R-value measure in building insulation?