After a couple of site visits, conversations and hundreds of reference photos, I got to work sketching out a plan of the building, the rooms and areas both upstairs and down, onto squared paper.
Once both floors were planned out, with everything lining up, I transferred the drawing onto isometric paper, where I started working upwards, plotting in the walls and walkways and making sure the map was clear and easy to read.
After a couple of inevitable tweaks, I was able to start inking up the final drawing. Using the lightbox I traced over the rough in ink, with crisp lines, adding in more detail as I went. Once inked the drawing was ready to be scanned again, imported into photoshop and coloured up digitally.
For the colouring, I used solid colour layers with vector masks for each of the large areas - the floor, walls etc. This makes the colours far easier to alter once it's all coloured up. When the base colours are all down, I started painting in the detail, shading etc and when finally happy with it, I dropped it into the indesign layout again, and sent it off to the client for approval.
The final project can be seen over in my Behance portfolio HERE