Wall joins

[philipdurban]

I'd be incredibly grateful for a few hints on how to get the wall joins to work in the attached images. In the second image I'm trying to get the straight wall to be a smooth tangent of the circular wall - but it's not working.
Thanks

[philipdurban]

I guess my question below was too basic, or too difficult - not sure which. If I expand on what I don't understand that may help!

How would I (for example) create a bullnose on the end of a free-standing wall. Do I need to use conceptual massing - or just cut/shape it somehow. I've done a picture in SketchUp to show what I need to achieve. Thanks.

[Dimitri Harvalias]

Both those end conditions can be resolved using in-place void families (extrusions or sweeps) or, if this is a common condition in this or other projects, you can create a face based void family. You might find the bullnose is a bit finicky if you try to use just a curve comign to a point. Make sure the curve has a straight element to it rather than feathering to a point.
Not sure why you are having join issues on the first case. When you use the join Geometry tool have you tried changing your pick order (straight wall first, curved wall second and vice versa) ?