A buildable envelope is the 3D volume you can build in once setbacks are taken off your site boundary. In Snaptrude you set a front, side or rear setback for each edge of the site, generate the envelope from those values, and then mass, arrange or pack your program inside it.
Before you start
You need a site in the project. To import one, click the project name, choose Import, then click Import Site in the Snaptrude's Toposolid section. Pick a parcel under Property Parcels and click Import site. Parcel data covers the US and Canada; elsewhere, draw the site boundary yourself. See Import a Site: Parcels, Terrain and Context and Draw a Site Boundary.
Setbacks and the envelope are set up in Design Mode. Site details and setbacks also appear in Program Mode on the site analysis sheet (for example, P1 - Site Analysis).
Create a buildable envelope
In Design Mode, select the site object.
In the Properties tab of the right panel, click Create buildable envelope.
Snaptrude creates the envelope and shows setback pills on each edge of the site so you can adjust them straight away.
The setbacks used depend on what the project already knows about the site:
If site analysis has been run and has produced setbacks, the envelope uses those values.
If not, each edge gets a default setback of 10 ft.
Note: The envelope reads its constraints from the Program Mode site analysis sheet. If you use Design Proposals, each proposal has its own site analysis sheet, so envelopes in different proposals can use different setbacks.
Change a setback on one edge
Setback pills on the canvas let you edit one site edge at a time.
If the pills aren't visible, select the site and click a setback input in the Properties panel. The pills appear on the canvas.
Click the pill on the edge you want to change.
Type the new setback distance for that edge.
To change how the edge is treated, set it to front, side or rear from the pill.
Tip: A change made on a canvas pill affects only that edge. Use it for irregular sites where, for example, one side boundary needs a larger setback than the other.
Change setbacks for every edge of one type
Select the site.
In the Properties panel, find the setback inputs.
Enter a new value for the front, side or rear setback.
A change in the Properties panel applies to every edge of that type. For example, changing the side setback updates all edges marked as side.
Analyze the site
Site analysis looks up zoning constraints for your site, such as setbacks and FAR, and writes them to the site analysis sheet in Program Mode. Those values then drive the buildable envelope.
In Design Mode, right-click the site and choose Analyze site, or select the site and click Analyze site in the Properties panel.
In Program Mode, choose Analyze Site from the agent dropdown and describe your site or project.
You can also ask the Snaptrude Agent to analyze the site and create the buildable envelope in one prompt.
Site details and setbacks stay in sync in both directions: edits you make in Program Mode show up on the site in Design Mode, and setbacks you change on the canvas are reflected in Program Mode.
Note: Review the results before relying on them. Site analysis lists its sources so you can check the zoning rules it used, and any values you type in a prompt override the ones it detects.
Work inside the envelope
The envelope uses the Envelope space type, which is drawn semi-transparent so you can see your massing inside it.
To fit program into it, select spaces or program blocks together with the envelope and use Arrange or Pack in the Properties panel. You can select a program block that overlaps an envelope directly, without isolating it first.
In the Area Panel (the Areas tab of the right panel), use filters to isolate the envelope when you're comparing areas.
Note: Arrange isn't available on the Free plan.
Show setbacks in Present Mode
Setbacks carry into Present Mode as dimension lines, so site plans can show setback distances without you having to dimension them by hand.
Troubleshooting
The setback pills disappeared. They show automatically only when the envelope is first created. Select the site and click a setback input in the Properties panel to show them again.
Every edge has a 10 ft setback. No site analysis setbacks were found, so the defaults were used. Run Analyze site or enter the setbacks yourself.
The envelope doesn't match my edits in Program Mode. Check that you're working in the same design proposal; each proposal has its own site analysis sheet.
Related articles
Import a Site: Parcels, Terrain and Context
Draw a Site Boundary
Site Analysis Sheet
AI Agents in Program Mode
Design with the Snaptrude Agent
Adjacencies, Arrange and Pack
Space Types, Area Types and Opacity
Design Proposals: Compare Options in One Project
The Area Panel: Net, Gross, FAR and Targets