Weatherproofing & Energy Efficiency Flashcards

A window's U-factor rating describes which performance characteristic?

Answer: The rate of heat transfer through the entire window assembly — lower is better

U-factor measures the rate of non-solar heat transfer through a window assembly; a lower U-factor indicates better insulating performance.

What is the correct practice for installing backer rod before applying sealant in a wide exterior joint?

Answer: Install backer rod to limit sealant depth to approximately half the joint width, creating a two-point adhesion joint

Backer rod controls sealant depth (ideally 1:2 depth-to-width ratio) and ensures the sealant bonds only to the two sides, not the back, for proper expansion and contraction.

Which energy code requirement addresses duct leakage in forced-air HVAC systems installed in unconditioned spaces?

Answer: Duct leakage to the outside must be tested and limited to a specified CFM25 per 100 sq ft of conditioned floor area

IECC requires duct leakage testing (at 25 Pascals) for ducts in unconditioned spaces, limiting total leakage to prevent conditioned air from escaping to outdoors.

A lead carpenter is coordinating the installation of a continuous layer of exterior rigid foam over existing OSB sheathing. What must be verified to maintain wall assembly moisture safety?

Answer: The foam thickness must be sufficient so the sheathing temperature stays above the dew point in winter, preventing condensation on the OSB

When adding exterior foam, it must be thick enough to keep the OSB sheathing warm (above the dew point) all winter, preventing moisture accumulation in the structural sheathing.

What is the primary weatherproofing advantage of a rainscreen wall assembly over direct-applied cladding?

Answer: It creates a drainage and drying plane behind the cladding, allowing any water intrusion to drain and the assembly to dry

A rainscreen gap between cladding and the WRB allows water that bypasses the cladding to drain harmlessly and the cavity to dry through airflow.

When replacing a sliding glass door, what flashing detail at the sill is most critical to prevent water intrusion?

Answer: Install a sloped sill pan flashing with end dams and integrate it with the WRB before setting the door unit

A sloped sill pan with end dams captures any water that bypasses the door and directs it outward, and must be integrated with the WRB to prevent water from tracking into the wall.

Which of the following describes the 'perfect wall' assembly concept promoted by building science experts?

Answer: A wall with all control layers (water, air, vapor, thermal) placed continuously on the exterior side of the structure

The 'perfect wall' places all four control layers (water-resistive barrier, air barrier, vapor control, and thermal insulation) continuously on the exterior of the structural frame, protecting the structure from all environmental stresses.