Half wall glitch?

WLWonder02  I've had that happen before.  When modifying the structure of a residential rental lot, the first thing you need to do is to move out the tenants, then have the landlord sell them lot.  Then go to build mode from the map as GalacticGal suggests.  It is usually best to reset all rooms to shared space before changing the venue to residential as well.  Once you do that, to get rid of the half wall, try building a room underneath it, then another room on top of that, that will replace the half wall with a full wall.  Then, starting at the top, delete the floor, then drop down, delete the walls, then the floor, drop down and delete the 3 walls not needed and paint the remaining exterior wall.  You might have to replace the roof there if there is supposed to be one.  If that doesn't work, I am willing to test the lot to see if I can find a fix for you.  All you need to do is upload the lot to the Gallery and reply here that you have done so.  Include the lot name and your userid if different than the one you use here (WLWonder02).  If you do, that will make it easier for me to find the lot in the Gallery.  I will test the lot and get back to you here in a day or so.

Hope this helps.