To run a 3-inch waste line the plumber has routed a vertical chase into the form face and cut about 1 1/4 inches into the concrete core over a 6-foot height. How should the inspector handle that chase?
- AAccept it; the foam face is not structural and a chase cut in the field is permitted wherever it does not expose reinforcement
The foam face is indeed not structural, which is exactly why cutting past it matters. The option stops one layer short and treats the cut as if it never reached concrete, when the stem says it went 1 1/4 inches in.
- BAccept it; chases are permitted in concrete walls to a depth of one-third the wall thickness without any further review
No such general allowance exists for concrete walls. The one-third figure is borrowed from the notching rules for sawn lumber, and applying a wood framing fraction to a reinforced concrete wall is the error this option represents.
- CReject it; grout may be packed into the cut, after which the wall returns to its full design thickness at the chase
Grout packed into a cut is unbonded and unreinforced, so it restores appearance rather than section. Any repair has to come from the designer who sized the wall in the first place.
- Reject it; the core carries the wall, so reducing its thickness needs the designer's evaluation and an approved repair
Why D is correct
The concrete core, not the foam, is the structural wall. A cut removing part of the core over a 6-foot height puts the wall outside the prescriptive thickness tables, so it takes an evaluation by the designer of record and an approved repair before the wall is accepted.
What this question is testing
Whether the candidate distinguishes the form from the structural core in an insulating concrete form wall, and knows that a condition outside the prescriptive tables goes back to the designer rather than being resolved by field judgment.
On the job
Insulating form walls hide their condition well: once the plumber tucks the pipe back and the foam is patched, nothing shows. Inspectors get to these before the interior furring goes on and probe any vertical chase with a screwdriver to see whether it stopped at the foam. Deep cuts happen most often for waste lines and radon piping, and they usually run the full height of the wall, which is worse than a single hole.
Memory technique
Foam is a form; concrete is the wall.
Exam tip
In an insulating form wall the concrete is the wall. Cut it and you are outside the tables.
Where to look it up
IRC Chapter 6, exterior concrete wall construction, together with the general requirement that work outside the prescriptive provisions be designed.