How can I "heal" wall gaps?

[svalen]

How can I "heal" wall gaps like these? Trim is not working,   or even redrawing a wall in the same location.

[barthbradley]

Typically see this in Phasing. Do you have a Wall there in another Phase?

Can you Disallow Join and drag wall end to meet other and then Join Geometry to hide visible edges?  

You can also use the Wall Join Tool on the Modify Tab to cycle through Joins.  

[ToanDN]

Disallow join the lower vertical wall, drag it to fill the gap, then join geometry all three walls. Alternately, turn on demolition and disjoin the existing/demolished wall that occupies that gap.

[_Vijay]

You better model as pet construction method.slab should be extended.

[svalen]

I don't have a wall join option,  really stumped with this one... I attached the file...

[hmunsell]

you have a New Construction phase wall there that is hidden in view.