Can’t close mesh

Hi! I imported a roof that was modified on Revit, I wanna connect the waffle component to it but it only detects one of the triangles of the surface and it says the rest of it is open, could somebody help me solve this? I have no idea of how to close the mesh. Thanks!

image (74.7 KB)

Your file contains 4 breps.
2 of them are closed and 2 of them are open.

The best solution would be to go back to the process that created these breps and correct it there.

I baked the breps and repaired them manually (explode, trim one of the overlapping surfaces, and re-join). (145.2 KB)