Hi there once again, when I go to extrude and scale down it won't let me reduce it only grows outwards.
If it reduces it moves it backwards. Thank you for all your helpful advice. Pic is at what point this happens.
I'm afraid I misled you when I said "press ALT + S to scale". Scale is the wrong word there. ALT + S "pushes" selected components outward according to the face normal - like a balloon blowing up.
In this case it takes all the flat planes and pushes them outward to create thickness for each plank. Try the ALT + S hotkey and see if it functions as expected (as demonstrated in the video).