Hi, Thank you for your detailed reply.

So, I added a new level, then drew the shape I wanted with the wall tool. I then double clicked inside the shape with the wall tool. I deselected the display ceiling made the colour dark grey and then selected the item and exported it to OBJ. When I then imported the OBJ using import furniture it came back in exactly the same and not solid.

Am I doing something wrong?

The shape really needs to be the whole outline of the building and then made solid if possible.

Thanks.