The work-around for getting to the roof of the middle CP in fastlane.
Fastlane Teleporter Trick - Middle Cap : Workaround
There used to be a way to build on to the roof of Fastlane's middle CP. But since the Scout update, the map was update and the fences around the CP used to get to the roof as an Engineer were removed. Fortunately there's still a way up.
Step 1: Setup
You will need a Teleporter Entrance, place it where-ever you like, but if you're in a public game I suggest your spawn.
Now go to the middle CP and place your sentry in one of the wooden corners.
Step 2: The First Tele
Jump on the sentry, and then on to a ledge almost next to you, get ready to place a teleporter exit, jump up and down on this ledge, looking at the planks above you, until you're able to build the exit.
Step 3: Setup II
After taking your newly made teleporter, walk along the planks until you're below the largest gap in the roof above you. Now place a dispenser there.
Assuming that you restored your metal before taking the teleporter (meaning you had 200, and used 100 on the dispenser, leaving you with 100), destroy the exit to collect atleast 25 metal, use this for the 2nd teleporter exit.
Step 4: The Second Tele
Jump on to your dispenser, and aim for the right-hand corner of the gap infront, jump towards the gap and place your teleporter there, this can take several attempts if it is your first time.
Step 5: Lock and Load
You're now on the roof, rebuild your stuff up there however you like.
Note: There is one flaw with this which is that the far right-hand flank can be used to soldiers and snipers to easily eliminate you and your buildings, this can be solved by having a second engineer build sentries closer to the flank, or by having classes defend this flank from such threats. Your goal on this roof is to block the 2 exits from the buildings infront, and to prevent people from capturing the point.
If these instructions were unclear, check the screenshots (with added captions and information), if that fails, take a look at the Youtube video (also by me):











