Thanks to Caz and Sarn who sent me the correct measurements for the side step card. I decided to be a bit creative with it and made a 'church' for a christening card. I opened the doors and added a picture on the inside of a forever friends bear with baby. The image of the window on the inside includes the window and I decided to follow that design through by hand drawing the windows on the door and the windows on the building. I think I managed to match them up pretty well.
Anyway, thanks to Caz and Sarn, I managed to get the measurements spot on and it stands and folds perfectly.