BAP BAP Weatherization & Retrofit Measures 1 — Questions and Answers
Question 1: Which air sealing location typically provides the greatest energy savings in a typical US home?
- Weatherstripping exterior doors
- Top plates and penetrations in the attic floor (Correct answer)
- Caulking around window frames on the exterior
- Sealing gaps around electrical outlets on interior walls
Correct answer: Top plates and penetrations in the attic floor
Attic floor penetrations — around pipes, wires, and top plates — are major air leakage sites because the stack effect drives warm air out at the highest points of the building.
Question 2: What is the primary function of a vapor retarder in a wall assembly?
- To prevent air from moving through the wall cavity
- To slow the diffusion of water vapor into or through the assembly (Correct answer)
- To reflect radiant heat away from the insulation layer
- To provide a fire barrier between insulation and framing
Correct answer: To slow the diffusion of water vapor into or through the assembly
A vapor retarder limits vapor diffusion through a building assembly, reducing the risk of condensation and moisture damage within the wall cavity.
Question 3: When insulating a rim joist in a conditioned basement, which approach is typically recommended by building performance standards?
- Batt insulation only, friction-fit between joists
- Rigid foam board cut and air-sealed in place, or spray polyurethane foam (Correct answer)
- Loose-fill cellulose blown into the rim joist cavity
- Exterior rigid foam applied to the foundation wall below grade only
Correct answer: Rigid foam board cut and air-sealed in place, or spray polyurethane foam
Rigid foam cut-and-cobble with foam sealant, or two-part spray foam, air-seals and insulates the rim joist simultaneously — a critical detail for basement energy performance.
Question 4: What is 'thermal bridging' and why does it matter in retrofit insulation projects?
- Heat transfer by convection through gaps in insulation batts
- Heat conduction through structural members that bypass insulation layers (Correct answer)
- Radiant heat gain through unshaded windows in summer
- Air leakage pathways created by improperly installed vapor barriers
Correct answer: Heat conduction through structural members that bypass insulation layers
Thermal bridging occurs when conductive framing members — studs, joists, headers — bypass insulation, significantly reducing the effective R-value of the assembly.
Question 5: A BAP analyst recommends dense-pack cellulose for an existing closed wall cavity. What tool is used to install it?
- A vacuum blower pulling cellulose through a return duct
- A high-pressure pump forcing cellulose through a fill tube inserted into the cavity (Correct answer)
- A low-pressure blower installed at the attic access
- A spray rig applying wet cellulose to open stud bays
Correct answer: A high-pressure pump forcing cellulose through a fill tube inserted into the cavity
Dense-pack cellulose is installed by inserting a fill tube into small holes drilled in the wall sheathing or drywall and using a high-pressure blower to pack cellulose to 3.5 lb/ft³ density.
Question 6: Which weatherization measure primarily addresses radiant heat gain through a ceiling rather than conductive heat loss?
- Adding R-38 blown cellulose to the attic floor
- Installing a radiant barrier on the underside of the roof deck (Correct answer)
- Dense-packing attic knee walls with fiberglass
- Air-sealing attic hatch with rigid foam board
Correct answer: Installing a radiant barrier on the underside of the roof deck
A radiant barrier reflects infrared radiation from the hot roof deck, reducing heat gain into the attic space in summer without improving conductive R-value.
BAP BAP Weatherization & Retrofit Measures 1
Which air sealing location typically provides the greatest energy savings in a typical US home?