[HELP] Double sided walls

[JustDawee]

Hi fellas!

I need some help, so I want to make a building to be enterable, I've tried 3ds max and Blender either but cant figure it out how to make it work.
Everything is fine in the editor but as soon as I export it to the game the "interior" is invisible from the inside. How to fix this? It's important that I want to make it work with the default world object, I've tried to remove it with removeWorldObject and creating it again with createObject with doublesided paramter, and yes in that way it works as I wanted but I want to make it work without removing it.

Is it possible even, or I am making something wrong here?
Inside view from Blender: https://i.ibb.co/VSQM2zR/blender-O6-ZChyp2uq.png
Inside view from ingame: https://i.ibb.co/mzTmvWD/gta-sa-YNta-W5ik2-A.png

[JustDawee]

I've just figured it out, in Blender you can overlay the faces orientation in RED and BLUE, the BLUE faces are visible and the RED faces are invisible, so you can just select the faces you want to be visible and go to Mesh -> Normals -> Flip and it should work!