Ok, so todayi at last imported my first house object for my game.
I take it from website that stated it is free to take, and i place it on unity.
after some time i take to correct the scale and materials, then i go to collders and rigidbody.
but when i test it, it fall through the ground (i checked “Generate Colliders” on Prefabs Inspector)
i try to do something and i at last add Box Collider… and BUM, it is not falling through anymore, instead the house bouncing a little…
up and down in the floor… i dont know how to show it, but if someone know how, maybe make a gif or anything i will do it to show…
what happened to my object? does this because the ground is a Plane? should i change it to a Box?
Thanks before. 
yeah apparently my friends told me to do that too.. so , thank you so much... that's my bad asking such a question :#
– Rgalaxy