The Site Analysis sheet is a table in Program Mode that holds the key facts about your site, such as site area, zoning, FAR and setbacks. AI site analysis writes its results here, you can edit any value by hand, and the sheet stays in sync with the site in your model. Snaptrude uses it when it creates a buildable envelope, so keeping it accurate keeps your massing accurate.
Before you start
Have a site in the project. Import one by clicking the project name, choosing Import, and clicking Import Site in the Snaptrude's Toposolid section (or search "import site" in the Search tools & actions box at the bottom of the screen), or draw a site boundary yourself. Site analysis can read both imported parcels and manually drawn sites.
If your project uses Design Proposals, check which proposal is active. Each proposal has its own Site Analysis sheet (see below).
Open the Site Analysis sheet
Click the Program tab at the top of the screen. Program Mode opens in a separate browser tab.
Open the P1 - Site Analysis sheet.
Note: If you haven't run a site analysis yet, run one (next section) or enter values by hand.
Fill the sheet with AI site analysis
You can populate the sheet in several ways. Every run is stored in the Site Analysis sheet, so the results are in one place whichever route you use.
From the Program Mode agent dropdown
In Program Mode, open the agent dropdown and choose Analyze Site. If you leave it on Auto, Snaptrude suggests an agent from your prompt; click Yes, proceed to accept or No, I'll select myself to choose.
Type your prompt, for example the site address, the intended use, or values you already know such as a zoning district or FAR.
To give the analysis more to work from, attach a document such as a zoning report (PDF) or brief.
Send the prompt. The agent detects the imported site and infers zoning and FAR. Anything you state in your prompt overrides the detected values.
From the Snaptrude Agent
Click the Agent button at the top of the far-left rail to open the AI chat panel.
Ask it to analyze your site, for example "Analyze this site for a mid-rise residential building." You can attach briefs or drawings with Attach files.
The agent writes its results to the Site Analysis sheet, even if Program Mode isn't open.
From the site in Design Mode
Select the site object, or right-click it.
Click Analyze site in the Properties panel or the Right-click menu.
Tip: For US sites, site analysis searches official code sources and includes reference links, so you can check where each value came from. Always review AI-derived zoning values against the governing code before relying on them.
Edit values in the sheet
You can edit the Site Analysis sheet directly. Use this to correct a value the AI got wrong, fill in a gap, or enter site data without running an analysis.
Open the Site Analysis sheet in Program Mode.
Click the cell you want to change and enter the new value.
When you re-prompt site analysis later, it takes your edits into account rather than discarding them.
How the sheet syncs with your site
The Site Analysis sheet and the site in your model are linked in both directions:
Site details and setbacks: change a setback or site detail in Design Mode and the sheet updates; change it in the sheet and the site updates.
Site area configuration: the sheet also syncs both ways with the site area settings used by the Area Panel.
Downstream agents: site constraints from the sheet are shared with other Program Mode agents, such as Research and Generate, so the program they produce respects your site.
Use the sheet to create a buildable envelope
A buildable envelope is the volume you can build within once setbacks and other site limits are applied. Snaptrude reads the Site Analysis sheet when it creates one.
In Design Mode, select the site object.
Click Create buildable envelope in the Properties panel.
Snaptrude creates the envelope using the setbacks from the Site Analysis sheet. If the sheet has no setbacks, it uses a default of 10 ft.
Adjust setbacks if needed. Changing a setback in the Properties panel applies to every edge of that type (front, side or rear). Clicking a setback pill on the canvas changes a single edge, and you can also set that edge to front, side or rear.
You can also ask the Snaptrude Agent to generate the envelope; it uses the same site analysis data.
Site analysis with Design Proposals
Each proposal has its own Site Analysis sheet, along with its own layers, saved views, program data sheet and area metrics. Site analysis runs on the active proposal. This lets you test different assumptions, such as alternative setbacks or a different FAR, in separate proposals without overwriting each other.
Troubleshooting
The analysis returned values that don't match the site. Check that the correct site is in the project and that the right proposal is active, then edit the values directly in the sheet or re-prompt with the correct figures.
The buildable envelope ignores my setbacks. Confirm the setbacks are entered in the Site Analysis sheet for the active proposal. Without them, the envelope uses the 10 ft default.
The agent couldn't complete the analysis. If you see an "unsupported functionality" or "response not given" card, try again with a more specific prompt, or attach a zoning document.
Related articles
Import a site
Setbacks and buildable envelopes
Program Mode AI agents
Snaptrude Agent
Design Proposals
Area Panel