Complex Mesh Light Maps

Does anyone have any good tips/tutorials for dealing with large, complex meshes from something like Revit and using light maps? I have large projects I am trying to do architectural visualizations on. Because of the size, I am bringing categories in as single meshes, like all walls as one fbx, all furniture as another, all ceilings, etc. I am unable to build the lighting without getting a ton of overlapping uvs or wrapping uvs errors. I have defaulted to just checking “force no precomputed lighting.” But now that I start to add interior lights, the scene is getting really bogged down running slow. I would like to be able to set those lights as static build/bake the lighting to improve performance. Right now if I try to build the lighting, objects get crazy patterns on them, I’m assuming from the messed up UVs, see the attached screenshot. Any advice or tips would be appreciated.

The issue is your lightmap UV’s, you need your second UV channel to be flattened out and fit into the 0-1 UV space:

In your case for something like walls, I would do an automatic flatten and then if you can’t get enough detail in your lightmap at a high resolution like 1024x1024 then split the mesh into separate objects so that it can use more lightmaps. Try not to separate anything on a flat surface, so for a wall you would want to split on the corners and not the middle of the wall.
For things like floors/ceiling just do a planar mapping.