Simulating physics using complex as simple collision?

I’m trying to make a game where a house I designed in UE4 is able to float around while still being enterable and traversable. I cant seem to find a solution to the physics of it. When I convert the house to a mesh and add complex as simple collisions, it doesn’t let me simulate physics and gravity. Are there any workarounds to this issue? The house is composed of only brushes converted to static meshes.

Add customized simple collision to the meshes.
you can actually export the meshes and make completely custom collision if you have to - however generating collision in engine can work too.
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