I’m trying to anchor shelves into an accent wall (whose construction is pictured), and I’m working to confirm where the actual studs are located.

**What I know:**
- The accent wall is built out **2 3/4”** from the original wall.
- The visible face is shiplap + drywall, which together measure about **1 3/8”** thick.
- That leaves about **1 3/8”** of depth behind the drywall, filled by OSB slats and possibly other structural layers.

**My questions:**
1. Are the OSB layer(s) mounted directly to the original wall’s studs?
2. Or is there a secondary set of furring studs or blocking behind the OSB, closer to the finished surface?

**The issue:**

There are two standard electrical boxes - one near the top left, one near the bottom right. Both are flush with the finished surface (shiplap + drywall).

If the original studs are recessed **2 3/4”**, and you add the original wall’s **5/8”** drywall, the studs are sitting **3 3/8”** back from the finished face.
A standard electrical box is only about **2.5”** deep.

How could an electrical box be anchored to a stud that far back?

**What I’m trying to figure out:**
1. Are these boxes not actually mounted to the original wall studs?
2. Is there additional framing or blocking closer to the surface that both the OSB and electrical boxes are attached to?
3. Or is there some alternate mounting method being used in this situation?

I had been planning to reinforce the affected shiplap slats using **2.5” SPAX screws**, assuming the OSB was sitting right on top of studs. But now I’m concerned they might not reach studs at all if they’re back at the original wall depth - especially since I can’t reconcile how the boxes are mounted.

Any thoughts or insights on this wall setup, or ideas on how confirm in a minimally invasive manner would be greatly appreciated!

Trying to understand accent wall structure