How should i use meshes ?

Guys,If i want to build a map with buildings , how should i use static meshes? For Example, I want to make destructible Wall, But does it matter if its merged with floor and glass (breakable) as one object, or i should make them as different objects,

If you have a wall as a destructible object you’d need it to be separate from things like the floor or window glass. You wouldn’t want them to be the same mesh anyways even if you weren’t making the wall destructible

Thanks! But i want ask one more question.What about shaped floor ? Should i take it as totally one, or i have to seperate it from shaped areas?

A good approach would be dividing a building meshes based both on materials and elements. So you might want to divide all concrete elements from metal ones. Then how much force is needed to destroy an element should obviously be based on its material type, the pyshical parameters set with PhysX (and soon with Chaos that is in beta).
So you would have all the concrete elements but not as a single mesh. You could still group them for each floor. So all the walls of outer walls of the first floor, inner walls of the first floor… and so on. Depending on how big and complex a building is that can take some time but it is worth doing it.
Then you should put the static meshes into BluePrints and add runtime code to swap the static ones with destructibles on impact adding logic to choose which actors would trigger the swapping and how much force is needed as well. This way you would ensure maximum performance and have full control on the simulation.