Azure Fang 
"[@Officer Hotpants":](/forums/dis/topics/video-game-thread?post_id=35402#post_35402
)
Always do. Whenever I restart (and this discussion is giving me the itch again) I have an entire process once I get to The Castle and get a supply line to it:
* Place a "key block" concrete foundation, clipped as deeply into the rubble as possible, close to the outer side of the ruined wall.
* Use position and rotation commands to align it flush with the wall, then disable/enable-cycle it to remove jitter caused by command manipulation.
* Construct the replacement wall, 2-3 layers high depending on how well I was able to sink the key block. Sometimes this takes building away then repositioning with console, if the foundations randomly decide not to top-snap.
* (Path side) Destroy the center and replace it with a powered door, then construct a shed around it for overall cover and ground floor turrets.
* On the inside snapa concre of the small barn floor tiles to the top, using that as an initial landing to snap metal staircases, placing railings on intermediate landings.
This time, though, I might eschew the flush building and "build out" a block or so from the wall so as not to interrupt the navmesh. Not as pretty, but better than watching an NPC walk in place or in circles for all eternity. The problem stems from the fact that, big surprise, the navmesh on many buildable tiles is either placed incorrectly or does not exist at all, so NPCs will not walk over them even if they're perfectly level as their pathing AI does not recognize the tiles as a valid surface.
Oh no, he's here?
Always do. Whenever I restart (and this discussion is giving me the itch again) I have an entire process once I get to The Castle and get a supply line to it:
* Place a "key block" concrete foundation, clipped as deeply into the rubble as possible, close to the outer side of the ruined wall.
* Use position and rotation commands to align it flush with the wall, then disable/enable-cycle it to remove jitter caused by command manipulation.
* Construct the replacement wall, 2-3 layers high depending on how well I was able to sink the key block. Sometimes this takes building away then repositioning with console, if the foundations randomly decide not to top-snap.
* (Path side) Destroy the center and replace it with a powered door, then construct a shed around it for overall cover and ground floor turrets.
* On the inside snap
This time, though, I might eschew the flush building and "build out" a block or so from the wall so as not to interrupt the navmesh. Not as pretty, but better than watching an NPC walk in place or in circles for all eternity. The problem stems from the fact that, big surprise, the navmesh on many buildable tiles is either placed incorrectly or does not exist at all, so NPCs will not walk over them even if they're perfectly level as their pathing AI does not recognize the tiles as a valid surface.