The bracing plan permits a diagonal let-in bracing method on this wall. The framer let a 1x4 into the faces of the studs and ran it from the bottom plate to the top plate at an angle you measure at roughly 30 degrees from horizontal. How should the inspector judge the brace?
- AAccept it; the angle of a let-in brace is not regulated so long as the brace reaches from the top plate down to the sole plate
Reaching both plates is necessary but not sufficient. The method fixes the slope because a brace flatter than 45 degrees delivers far less of the racking force into the plates, and a very steep one gathers too little wall length.
- Reject it; the method requires the brace to run between 45 and 60 degrees from horizontal, and this one is flatter than that
- CAccept it; a 1x4 let in flush with the face of the studs satisfies this bracing method whatever slope the brace takes
Letting the brace in flush is how the member is installed, not what makes the method work. Material, fastening and slope are all specified, and satisfying two of the three does not produce a braced wall panel.
- DReject it; let-in bracing may be used only in interior walls that carry no load from the framing above them
Let-in bracing is a bracing method for braced wall lines that do carry load. Restricting it to non-load-bearing walls confuses it with the ordinary partition framing rules, and it would leave the exterior wall unbraced.
Why B is correct
Let-in bracing is defined by its geometry as much as by its material. The permitted range of 45 to 60 degrees from horizontal keeps the axial force in the brace and the demand on its end connections inside what the method was tested for.
What this question is testing
Whether the candidate knows that a prescriptive bracing method carries geometric limits, and can recognize that a brace outside those limits cannot be counted even though it is real, continuous and properly let in.
On the job
Let-in bracing turns up on garages, accessory buildings and small additions where the builder wants to leave sheathing off. Long walls tempt the framer to lay the brace flat so it clears the openings, and the resulting 25 to 30 degree runs are common. Inspectors carry an angle finder or simply check the rise and run against the studs, since a brace crossing three stud bays over a full wall height is roughly right and one crossing six is not.
Memory technique
Between forty-five and sixty, or it does not count.
Exam tip
For any diagonal brace, check the angle before you check the fasteners.
Where to look it up
IRC Chapter 6 wall bracing, the table of bracing methods and the description of the let-in bracing method.