Simulate Collisions on Building

So I am putting together a game that needs to have a building that you can enter and see the textures in the inside, but you can walk through walls, how do I do collisions for that?
Do I need a whole bunch of primitives for all the sides?
Thanks!
Also this game targets high end devices if that helps at all!

Either you put a lot of primitives there or you can use a mesh collider and set it to the visual model of the building. Beware that if the model contains small details like lamps, chairs, or other detailed geometry in general, you should consider creating a simplified version of your building just for the collision geometry

So that was my idea at first but will a mesh collider block the character from walking into the building?

Well, you’ll need a door, obviously.

Can you be a bit more specific with what you already tried and what you’re trying to achieve?

Sorry for being slightly vague, the game is set on Mars and you need to get through the airlock to be able to get inside. I am going to make a low poly mesh for the mesh collider but a box collider has 6 faces, and I just don’t want a face to obstruct the doorway that the player will enter. The mesh collider only stays on the mesh right? That was my question.

Ah, I see. Colliders are not only their surface, but also define an inside and an outside. A box collider is a filled box, so you can’t make a door into it. A mesh collider can be hollow, but I actually needs to be modeled hollow.

So instead of completing the house you model the house without the door and add the door collider as a box right? You just have to have one open spot correct? If not how would you make sure the mesh collider doesn’t have the inside in the structure?
Thanks so much for your help