Core TradesQuestion 205 of 700
To completely fill the cavity of a nominal 2x6 wood-framed exterior wall, which batt insulation R-value is most typically specified?
a.R-11
b.R-15
c.R-21
d.R-30
Explanation
A high-density R-21 batt is sized to fill the roughly 5.5-inch cavity of a 2x6 wall. R-11 and R-15 are intended for shallower 2x4 walls, and R-30 is a ceiling/floor value too thick to fit a 2x6 wall cavity.
Law Reference: 2025 CA Energy Code (Title 24, Part 6)Practice all 700 questions free — no signup required.
Related questions on this topic
- Proper flashing where a masonry chimney passes through a sloped roof generally consists of:
- A roof plane rises at a 5:12 slope over a horizontal run of 15 feet. What is the vertical rise?
- For an enclosed attic without a vapor retarder or balanced venting, the net free ventilating area must generally be at least what fraction of the vented attic floor area?
- A blower-door test performed on a completed home measures PRIMARILY the building's:
- For window head flashing to work correctly with a water-resistive barrier, the barrier above the window must be lapped so that it:
- A vapor retarder placed directly under a concrete slab-on-ground in habitable space is commonly required to be polyethylene sheeting with a MINIMUM thickness of:
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against California CSLB General Building (B) Trade Examination · How we review