Site boundary, slopes and spot elevations

Add a site to model the ground your home sits on. The terrain is built from the elevations you enter, so decks, patios, trees and outdoor furniture stand on the real ground level.

Before you start

• Your ground floor drawn (the site is shown with the ground floor).
• Optional: ground heights from a survey or a site plan. Heights are measured from project zero, the level of the ground floor's elevation of 0.

Create the site

1. Open Roof & site in the left rail and find Site & terrain.
2. Choose Add site to use your building plus 5 m (about 16 ft) on every side, or Draw boundary to click each corner of your property line. Click the first corner again or press Enter to close it; Backspace removes the last point.
3. Choose the Ground surface: lawn, stone pavers, decking or sand.

Add spot elevations

1. Choose Add spot elevations. The plan switches to the ground floor.
2. Click the plan where you know the ground height. A marker appears and its elevation field is ready to type, for example -1'6" or -0.45 m.
3. Add as many points as you need. Drag a marker to move it; select one to edit its value in the panel or remove it.
4. Press Escape or choose Done when finished.

The plan shows each spot with its value, plus contour lines every 0.5 m (or 1 ft) so you can read the slope at a glance.

How the ground is calculated

• The terrain is a triangulated surface through your spot elevations. Between spots the ground changes in straight lines.
• Along the boundary, the ground height is blended from the nearest spots. With no spots, the site is flat at project zero.
• In 3D the house sits in the terrain: the ground is cut around the building, and where the ground is lower than the ground floor a foundation wall is shown.
• Furniture and landscaping on the ground floor that is outside rooms (trees, outdoor furniture, a hot tub) sits on the ground level in 3D. Items inside rooms stay on the floor.

Decks and patios

1. Draw the deck or patio as a room on the ground floor, or place an outdoor item.
2. Select it. The panel shows the ground under it: a suggested patio level (on the ground, the average height under it) and a deck level (one small step below your ground floor) with the space left underneath.
3. Use these numbers to set the deck height, steps or retaining edges.

Current limits

• Spot elevations are the only terrain input; there's no import of survey or contour files yet.
• The terrain follows the boundary closely but isn't clipped exactly at very sharp inside corners.
• Retaining walls, cut and fill volumes and drainage aren't calculated.
• Items placed on upper floors, and items inside rooms, don't follow the terrain.

Common problems

• "Spot elevations must be inside the site boundary." Click inside the boundary, or redraw the boundary to include that area. Redrawing a smaller boundary removes spots left outside (undo restores them).
• The ground covers part of the house. Your spot elevations near the house are higher than the ground floor. Check the values, or raise the ground floor's elevation.
• I can't add spots. Spot elevations are added on the ground floor; the panel switches floors for you when you choose Add spot elevations.