I have been working on a little project for a while now but have hit a snag. When I go to create some styles of roofs I use the Geometry tool to do so and I am getting a weird effect when i place the piece where I want it to go. I will show you two images of what I am talking about. The first image is what is happening when I place the piece where as the second image is before placement. Now if I place the piece I can drag it to the left or right of the spot I want it placed and it will return to its proper solidity, however when I drag it in front of the piece, long as it is level with where I want it to be, it will still have the bsp partially gone. It will eventually fill back in though depending on how far out you go. What is causing this.
This is a well documented problem that has been around for over a decade - commonly referred to as the UnrealEd BSP Goblin.
You should avoid overlapping brushes, and where possible, avoid subtractive brushes.
nothing is overlapping and I only use subtractive for doors and windows on this model. but I will look into it again and see what we have going on.
It can also happen if you’re editing points using the geometry tools.
ok. have another question for you. When doing lighting, how do I get my rooms to show the light from outside. I am using a directional light to light up my world but none of that light makes it through the windows/doors into the house. I thought u use reflection captures but that isn’t working. and I don’t want a million point lights since they like to bleed through the walls at some points.
Don’t use BSP to model stuff like that, it runs poorly and the modeling tools are limited, you’re better off modeling in a separate 3D program and exporting to UE4.
As for lighting, besides the directional light you need environment lighting like a skylight or by adjusting the environment color/intensity in the global Lightmass settings.
I would wish that the BSP was better…
I don’t know if it’s still in the plan but they would like to make better tools. But even with some better tools there’s not much reason to use it. 3D programs have better modeling than what you’d ever get in the editor and static meshes run better anyways. The only advantage to BSP is that it’s already in the editor so you don’t have to export to UE4, though it only takes a few seconds to do that.
I have a directional light as well as a skylight but none of the light gets into the house. I guess I could just put point lights in each room to help illuminate the room but will that be needed if I model it in 3ds ?
Set them to “moveable” and check it again or click on the “build” button 
If you’re using static/stationary lights make sure you build the lighting.