Wallrap Support

Open the app and tap Start on the Listen tab. Knock the wall firmly with one knuckle — not too hard, not too soft. The chip will show HOLLOW, EDGE, or SOLID. Calibrating first (Calibrate tab) makes the readings more accurate for your specific wall.

On the Calibrate tab, tap "Capture" under Step 1 and knock a spot you know is hollow (between studs). Then tap "Capture" under Step 2 and knock a spot you know is solid — a door frame or a spot where you can feel a stud. Tap "Save calibration." The app uses these references to tune the classifier to your wall.

Hold the phone vertically against the wall. Tap "Start trace," then knock every 1–2 inches as you slide left-to-right. The colored strip updates in real time: amber = solid (likely stud), blue = hollow (cavity), purple = edge (uncertain). Tap "Stop" when done. If the trace looks promising, tap the save icon in the top-right corner to save the session.

In Listen mode, the Snap-to-Stud gauge tracks the last 3–5 knocks. When the last three or more knocks all agree with high confidence, the banner changes to "STUD FOUND" or "CAVITY CONFIRMED." This is much more reliable than reading a single knock — keep knocking the same spot until the banner locks in. The colored dots below the gauge show the recent knock history.

After running a trace with enough solid regions detected, a "Spacing estimate" card appears below the trace strip. It shows whether the gap pattern between solid segments looks like 16" on-center (the most common US residential standard) or 24" on-center, along with a confidence bar. If the result shows "?" it means the trace doesn't have enough periodic data — try a longer pass with more knocks.

After stopping a trace, a save icon appears in the top-right corner of the Trace screen. Tap it to open the save sheet. You can add an optional note (such as "Living room north wall") before saving. The session is stored locally on your device and appears in the History tab.

The History tab lists every saved trace session, newest first, with the date, optional note, knock counts, and spacing estimate. Tap a session to view the full wall map and details. Swipe left on a row to delete that session. Tap the trash icon in the top-right to delete all sessions at once.

Open a session from the History tab and tap "Export CSV." The iOS share sheet opens and you can AirDrop the file, attach it to an email, save to Files, open in Numbers, or send it to any compatible app. The CSV includes one row per knock with timestamp, spectral centroid, band energies, label, and confidence percentage.

Open a saved trace from the History tab. The Mount Check card shows the strongest candidate anchor point, a confidence score, spacing evidence, warnings, and a short checklist. Use it as a verification guide, not as final permission to drill. Always confirm before mounting heavy objects or drilling near outlets, switches, plumbing, tile, or unknown cavities.

In Settings, the Sensitivity slider controls how loud a knock must be above the ambient noise floor to trigger a detection. Lower values detect softer knocks but may pick up ambient noise. Higher values require a harder knock. The default (12 dB above noise) works well in a quiet room. In a noisy environment, raise it to 16–20 dB.

Wallrap plays a distinct haptic for each classification: a crisp, strong impact for solid; a softer, lower thump for hollow; a neutral tap for edge. You can toggle haptics on/off and adjust intensity in Settings. Haptics require a Taptic Engine (iPhone 6s or later). iPad does not support haptic feedback.

Wallrap is an acoustic estimator, not a certified stud finder. Noisy environments, inconsistent knock force, thick walls, plaster-on-lath, textured surfaces, and metal studs all reduce accuracy. Always confirm stud positions with a drill pilot hole or a hardware stud finder before driving large fasteners or anchors.

Settings → Erase calibration removes the stored hollow and solid reference and reverts the classifier to factory defaults. Use this if you move to a different wall with different acoustic properties and want to start fresh.

Email support@shadowfetch.com with your device model, iOS version, and a description of the issue. We respond to every message.