ConceptDraw Community

I found it was easy to change dimensions via keyboard when using the preset room shapes ( box, T shape Etc..) but is there an easy way to type in dimensions for a custom size room?

Yes,
for win: in Geometry floating dialog you can change sizes manually.
To open Geometry use: menu View-> Floating dialogs-> Geometry

For mac in the inspector Geometry:
menu Inspectors-> Geometry