Edges too far apart to merge. Tried all that I know and more!

I am trying to create a diagrid on my building by bringing in my building form as a single surface into grasshopper. I was able to merge the exterior side and top to create one surface (red) but I am unable to merge the last surface (green) so that it is one continuous piece. I have tried extendsrf & split, I have also tried matchsrf, and extend edge with split. I need this as a single surface, not a polysurface or mesh. Any and all help will be so appreciated
Please Help.3dm (706.2 KB) .

Hello - why do you need to merge? Join will not do?

-Pascal

Joining the two surfaces creates a polysurface, not a single continuous surface.

I know - I was asking why that matters - but anyway - to merge these, you’ll need to line up the seams - use ShowEdges > All edges, to show the vertical seams - they are opposite one another. Use SrfSeam and End Osnap to swing one seam around to exactly match the other.

-Pascal

I scale the object down then i rebuild all surfaces to reasonable smooth surface and that gives me 1 surface.Please Help_sol1.3dm (2.4 MB)