Thank you for your reply. I have built the walls with the polygonal tool because the existing building is a fort and the walls are very thick sometimes over a metre wide and curved, however because the heights are different around the building with domed and curved ceilings I had to build several walls. Where they meet a line occurred. I have been using AC since Jan 2010 so fairly new to it. There is probably a better solution but i am not aware of it. This work is for my Degree project. (i'm in my third and final year) I am the only student using AC in my year, So I really appreciate the help i'm getting from this forum