How do you handle not going through walls in SteamVR using fading to black?

I am using HTC VIVE and i would like to know how you handle the way to not going through walls using fade to black color as i can use SteamVR fade script which works but then when the players gets out of the wall collider i must fade out and that happens when the player reach the other side of the wall making the system useless as they can go through walls just walking through the room