This can be done immediately after getting the Timepiece item in Mission 7: A Crack In The Slab. Leave the room where you obtained the Timepiece, and switch to the past. In the long corridor, go through the first door on the right, jump up the shelf in the kitchen, switch to present time, and go through the opening in the wall. You will now be in a new area with a balcony. Switch to past time and shoot the two support beams off the balcony. When you switch back to present time, the balcony will have collapsed. Climb up to get the "Dilapidation" achievement.