Walking up and down The Lodge front stair, on the top tread there are odd patches of brown and white. These are parts of the room under the stair.
(This has bothered me for ages, but I'd always expected somebody else would fix meshes. I'm not a NifSkope expert.)
The room does not properly align with the flooring above. Trying to fix the room x+y leads to an insurmountable number of conflicts. The worst being that the gold stripe on the floor at the base of the walls is a single model, covering the entire main floor. Doors and navmesh need to be adjusted, too.
My solution is to lower the ceiling beams and white walls until they are not visible. Existing woodwork covers the gaps. The walls are one piece, and now stick below the floor into the space below, but there's nothing there.
That leaves a tiny part of the stair decoration showing inside the room above the doorway, so I've adjusted that, too.
Of course, this is not the worst and most obvious glitch, that the stair to the basement sticks out the front of the building. And the exterior model upstairs isn't even close to the interior dimensions.