Airlocks can be overbuild with walls

In fact, walls (normal and insulated, not tested yet with metal, plastic and glass...) can overbuild also power-joints. 

If i remember correctly, this was not possible in earlier versions, and its annoying, if you want to just quickly insulate a whole wall for example. My dupes got stuck 2 times inside a room, because the door got overbuild, before i recognized the issue.