Summary: I ordered two wall-mounted lamps built on the front wall of my newly finished building. One of them was placed directly, without first having the ladder built, whose blueprint was visible. The ladder blueprint was removed along with the lamp’s at that point, at least. The other wall-mounted lamp was built after the construction of the ladder, as expected.
Steps to reproduce: Really not sure, as it happened seeminly randomly for one of the two lamps I had ordered placed at the same point in the game.
Ordered at 31:30. Built without ladder at 31:45. Built with ladder immediately after that.
Versions and mods: No mods, latest release version in Steam at the time of writing, version 0.1.0 (release 122) according to the title screen.
OS: Windows 8 Pro 64 bits (6.2, build 9200)
Processor: Intel® Core™ i5-3450 CPU @ 3.10GHz (4 CPUs), ~3.5GHz
Memory: 8192MB RAM
DirectX-version: DirectX 11
Graphics card: NVIDIA GeForce GTX 660