---
title: Revision Delta Report
slug: revision-delta-report
summary: "When someone changes the building model, FrameAI shows you exactly what changed and whether it is still safe — like a 'diff' for buildings."
youll_need:
  - "A model in Studio with at least one previous version"
  - "~3 min"
steps:
  - "Open your model in Studio → go to 'Revisions' (clock icon in the toolbar)"
  - "Select two versions: the older version and the current version"
  - 'Click "Generate Delta Report"'
  - "Wait ~20–40s for analysis"
  - "Review: additions (new members), removals (deleted members), modifications (changed properties)"
  - "Each change is colour-coded: green = added, red = removed, yellow = modified"
  - "Click any change to jump to that element in the 3D viewer"
what_you_should_see: "Delta report page showing change summary at top (X added, Y removed, Z modified) and a scrollable list of all changes below"
common_problems:
  - "Only one version available: Delta reports need at least 2 saves — keep working on your model and save again."
  - "Changes not detected: Minor cosmetic changes (e.g., text labels) are ignored — only structural geometry and material changes trigger a delta."
  - "Delta report is empty: Check that both versions are the same structure type — comparing a steel model to a concrete model gives a blank delta."
  - "Large model causes timeout: For models with >10,000 members, delta reports run in chunks — check back in 2–3 minutes."
video_slug: revision-delta-report
category: eurocode
locale: en
---

## Revision Delta Report

When the structural model changes — a beam section swapped, a column removed, a connection redesigned — FrameAI shows you exactly what changed, and whether it is still structurally valid. Think of it as a `diff` command for buildings.

### Before you start

| Item | Details |
|------|---------|
| Prerequisites | Model must have at least 2 saved revisions |
| Comparison | Any two revisions can be compared |
| Time | ~20–40 seconds for analysis |

---

### Step 1 — Open the Revisions panel

In Studio, open your model. Click the **clock icon** in the toolbar to open the Revisions panel.

```
<div class="screenshot-placeholder">
  📸 Screenshot: Studio toolbar with Revisions (clock) icon highlighted.
  TODO: replace with actual screenshot
</div>
```

### Step 2 — Select two versions

The Revisions panel shows all saved model versions in reverse chronological order. Select:

1. **The older version** (your baseline)
2. **The current version** (or any other comparison point)

```
<div class="screenshot-placeholder">
  📸 Screenshot: Revisions panel with two revisions selected for comparison.
  TODO: replace with actual screenshot
</div>
```

### Step 3 — Generate Delta Report

Click **Generate Delta Report**. FrameAI runs a structural diff between the two versions.

```
<div class="screenshot-placeholder">
  📸 Screenshot: Delta Report generation in progress with progress indicator.
  TODO: replace with actual screenshot
</div>
```

Analysis takes 20–40 seconds depending on model size.

### Step 4 — Review the changes

The Delta Report shows:

- **Change summary at the top** — X added, Y removed, Z modified
- **Scrollable list of all changes** below

Each change is colour-coded:

| Change type | Colour | Meaning |
|-------------|--------|---------|
| Added | Green | New member added to the model |
| Removed | Red | Member deleted from the model |
| Modified | Yellow | Member property changed (section, material, orientation, etc.) |

```
<div class="screenshot-placeholder">
  📸 Screenshot: Delta Report with colour-coded changes for added, removed, and modified members.
  TODO: replace with actual screenshot
</div>
```

### Step 5 — Jump to changed elements

Click any change in the list to jump to that element in the 3D viewer. The viewer pans and zooms to centre the selected member, with the change highlighted in context.

```
<div class="screenshot-placeholder">
  📸 Screenshot: 3D viewer centred on a modified member with change indicator.
  TODO: replace with actual screenshot
</div>
```

---

## What you should see

A Delta Report page with:

- **Header summary** — e.g., "5 added, 2 removed, 12 modified"
- **Colour-coded change list** — scrollable, filterable by type (added/removed/modified)
- **3D viewer jump** — click any change to navigate to the element in context

---

## Common problems

**Only one version available**
> Delta reports need at least 2 saved revisions. Keep working on your model — every manual save creates a new revision point. Auto-saves also count.

**Changes not detected**
> Minor cosmetic changes (e.g., text labels, annotation notes, colour overrides) are ignored by the delta engine. Only structural geometry changes, material changes, and section property changes trigger a delta entry.

**Delta report is empty**
> If both versions are structurally identical, the report is blank. Also check that both versions are the same structure type — comparing a steel portal frame to a concrete frame gives a blank delta.

**Large model causes timeout**
> For models with more than 10,000 members, delta reports process in background chunks. If you see a timeout message, check back in 2–3 minutes — the report will be ready in Studio.

---

## What's next?

- [Night Shift](/docs/tutorials/night-shift) — schedule overnight re-checks after model changes
- [Run Eurocode Calculations](/docs/tutorials/run-eurocode-calculations) — verify that changed members still pass

Prefer to watch? [Watch the video walkthrough](/videos/revision-delta-report)