building grid how to show and dimension to it in a drawing.

I would like to understand how other companies set out building grids.

I work in the sawmilling industry.- and most machinery items we create need an individual g/a layout so the item can be placed within the building.

Note the grid identifications are made by the Architect and I would use their labelling system.

Our buildings are usually only 1 or 2 levels.

And often the construction lines we refer back to are imaginary lines like the cl of a band wheel and the cl of a column.  But these are critical layout dimensions.

This is the building grid as I had it in my 2d cad system.

I tried making it a block and inserting it on the drawing sheet  and then dimensioning to it.- It didn't work.

My questions are

1) what are the different ways to do this - part of an assembly or in the drawing sheet itself.-

2) Can you dimension to planes in a drawing?- a plane that has no model item associated with it?

I have always found sketching lines to aid dimensioning in Solidworks drawings trial and error. ie: showing a floor level that is not part of the machine.

I would appreciate any suggestions.

Cheers Kiri

SolidworksDrawings And Detailing