Two open polygon meshes to 2 close polygon meshes. How?

Hello all,

for a 3D print I need 2 closed surfaces. Unfortunately I can’t get the polygon meshes to be 2 single closed polygon surfaces. It should still be 2 flat, but completely closed. Can someone help me? :confused:

Roof.3dm (977.6 KB)

the grey object has some holes, simply join all of it together and use FillMeshHoles.
the red object consists of a polysurface (grey) and mesh (red) that will not work. for a quick fix to print delete the grey side part and use the same command pointed out above or fillmeshhole.

see this video - (works for rhino 7 too)