Lo-Fi Games

Anyone know if we are supposed to be able to upgrade the wall levels from 2 to 3 and 4 or do we have to rebuild them completely?

From what I have found you have to dismantle the old and build the new, before I realized the Mark V walls couldn't be properly build by the NPCs, I decided I would build the new walls around the old and dismantle them afterwards. There does not appear to be an option to upgrade already existing walls.

there isn't and might not be a option for it, for each wall type gets bigger, taking up more space.