When do the provisions in an appendix of the residential code become enforceable in a jurisdiction?
- Automatically, whenever the main body of the code has been adopted
- Whenever the building official decides to apply them to a project
- Only when the owner agrees to them on the permit application
- Only when the adopting ordinance specifically adopts that appendix
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D. Only when the adopting ordinance specifically adopts that appendix
Appendix chapters are not part of the enforceable code unless the jurisdiction names them in its adopting ordinance. Adoption of the main body alone does not bring them in, and the building official cannot adopt them by choice.
Reference: IRC 2021, Chapter 1 (Scope and Administration): appendices
Asphalt felt is being applied horizontally as a water-resistive barrier on a wall. How should the courses be lapped?
- Each lower course laps over the course above it, to lock it in
- Each upper course laps over the one below, shingle fashion
- The courses are butted edge to edge and sealed with caulking
- The lap direction does not matter if cap staples are used
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B. Each upper course laps over the one below, shingle fashion
Water runs downhill, so each upper layer must overlap the layer below, the same way shingles lap. Reverse laps funnel water behind the barrier and into the wall, which is one of the most common leak causes an inspector finds.
Reference: IRC 2021, Chapter 7 (Wall Covering): exterior covering; water-resistive barrier
Two windows are being compared. Window A has a U-factor of 0.30 and window B has a U-factor of 0.45. Which window loses less heat?
- Window B, because a higher U-factor means more insulation
- Neither; U-factor rates only solar heat gain in summer
- Neither; U-factor rates only air leakage around the sash
- Window A, because a lower U-factor means less heat flow
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D. Window A, because a lower U-factor means less heat flow
U-factor is the rate of heat transfer through an assembly, so lower is better. It is the inverse of R-value. Treating U-factor like R-value, where higher is better, is the common mistake.
Reference: IRC 2021, Chapter 11 (Energy Efficiency): fenestration U-factor
Under the residential code's general rule, how much must the finished grade fall within the first 10 feet from the foundation?
- At least 2 inches
- At least 12 inches
- At least 3 inches
- At least 6 inches
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D. At least 6 inches
The grade must fall a minimum of 6 inches within the first 10 feet. Where lot lines or other barriers prevent that, drains or swales are used instead. Two inches in 10 feet is the kind of slope used for impervious surfaces and is too flat for soil against a foundation.
Reference: IRC 2021, Chapter 4 (Foundations): drainage
What is the minimum bearing length for the end of a wood floor joist or beam that rests directly on masonry or concrete?
- 3 inches
- 1-1/2 inches
- 2 inches
- 6 inches
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A. 3 inches
Bearing on masonry or concrete is at least 3 inches, twice the 1-1/2 inches required on wood or metal, because the member must spread its load over a material that can crush or spall at a narrow edge.
Reference: IRC 2021, Chapter 5 (Floors): wood floor framing; bearing