Using the example of the wall cutting through the view out of a Velux in a sloped ceiling.
1. Reduce the height of the wall to match bottom of slope height.
2. Change to Elevation View looking at the wall that you have just reduced the height of.
3. Go to InsertAuto Features▼Edit Graphic Fixtures
4. Select FreehandAdvanced Graphics*BOX or similar
5. Now draw in Manually by clicking the hotspots to the required shape
If your design requires Radius, Convexes, Concaves etc.. or even to extend or split the shape you can do this now in the same way you would when editing Worktops.
6. Continue through the Edit Graphic Fixtures Wizard by clicking Next Step Until you reach and Click Finish.
Your *Box will now be visible on your plan and you can now position it accordingly.
7. Final Step in this example was to change the colour of the *BOX to match the wall. However if you have used *BOXW this will already be the correct colour.
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How to Add a Sloped Ceiling
How to Add a Velux Window to a Sloped Ceiling