Press the "S" key to disable or enable automatic snapping in the wall structure.
Using the same "S" key you can switch the grid snapping feature on/off at any time.
If you are having trouble placing an element i.e. door/window, use the mouse scroll wheel to zoom out until you can see the full plan and then place the element.
See article KB113 for further information
This article is valid for DomuS3D® 2017 and later versions