Hi,
I’m new to plusSpec and sketchup and am wondering whether its possible to set AHD levels anywhere?
Hi Stacey_S & welcome!
The 
Levels & Layers Tool allows you to specify & set vertical heights in your model, so this should do what you’re after. If you click on the orange ? icon in the dialog (circled in the image below) you’ll be taken to a tutorial playlist of videos specific to the tool which will explain in more detail what the tool is, what it does & how to use it.
Note: If you’re planning on drawing at the AHD levels you’ll need to adjust sections created via the 
Scene Tool to suit the new heights (they are set to 1.5m above the level height). For ease of use & to minimise the amount of adjustments needed, we normally recommend to always draw the ground floor at the model axis & set the level heights of the structure from there.
