Imported a model as FBX from C4D but it looks weird

I don't really know how to explain it in words...
So here's a gif showing my issue:
https://imgur.com/a/xuC3YUz
Why am I able to see through my house but it's solid? The cutout in the door was made by Bool.

 

probably 1 sided mesh (example: unity doesnt draw backside of a plane mesh)

in 3ds max can use Shell modifier to make mesh 2 sided, not sure about c4d..

 

I still don't get it. In c4d it is solid, meaning, I can see the wall through the door.

 

oh i see, initially its partly visible, then inside its not.

can you show wireframe view of the building?

 

Yup. Here you go:

 

Also, my window looks like this in the unity scene...:

But this is how it looks like in C4d:
https://imgur.com/PGEXF9n

Here's the link to the house in both c4d and fbx formats (in case you want to have a look): https://www.dropbox.com/sh/kfod1wsb0i3vbi9/AAANlzUWC0oNNOklc4YqySjpa?dl=0

 

*ok got the model

 

That's the window.

 

so the black part (that looks like wall) is actually door,


can see in the gif the door handle,


but the main issue with back wall and window frames is still the one sided mesh.

 

If you enable backface culling (keyboard shortcut toggle N~P) you can see how it will look in unity.

My recommendation is also to work with your viewport -> Options -> Polygon Normals enabled, that way you can make sure your normals are facing outward