I cant subtract with a Brush how you can see.
Did I do something wrong?
If you are using 4.8 those walls are static meshes. The subtractive brush will only work with other BSP brushes.
can i subtract on a different way?
Not from a static mesh. You can place a BSP Box in the scene and set that to the size you would like. Then you can use the subtractive brush with it.
If you want to edit a static mesh you’ll need to do that in a modeling program like Blender, 3ds max, or maya.
Sorry to bother, but what is the difference between a static mesh and a BSP? What is a BSP?
I want to create a Room, should I Use bsp or static mesh?
Also I want to use multiple times this room, like copy and paste but I don´t want to have all parts of the room separated, so what I do is to select all of them, right click and “convert to static mesh”… is this possible with bsp?
You can! If you select all of your meshes, and then in the advanced section of your Brush Settings, there is a button called “Create Static Mesh”
it is possible to substract meshes with “modeling” tool