Strange behavior of roofs in alpha 15

[Doc_Brano]

Summary:
Roofs appear inside walls
Steps to reproduce:

1. make a building with a tower and a lower part
2. place the roof on the lower part
3. roof appears inside the tower

Expected Results:
only to put roofs on the lower part
Actual Results:
place roof inside the tower on top of second floor
Notes:
I do have a work around this issue, build the roof before the tower is placed.
Attachments:

Version Number and Mods in use:
version alpha 15 no other mods
System Information:
win7 64 bits intel i5 3.20 ghz 8ddr3 ram nvidia gtx 650

[Relyss]

Paging @not_owen_wilson (although I think this bug is already known).