started by Fidcal
When mapping, if you find some brush surfaces are not rendered and show black, try rebuilding part of that section with a slight variation.
Please add examples and solutions:
Often seems to relate to brushes that touch. I had this with a trapdoor made of boards with two crossbeams supporting underneath. The trapdoor was mostly black from above but visible from below. Thinking the crossbeams split it up and helped it to render I put two more crossbeams above as well. Now it was black from below as well. So I removed the top crossbeams and moved the bottom ones away from the door by a tiny amount and then it was OK. I suppose I might also have tried reducing the length and/or width of the crossbeams instead. But it wouldn't surprise me if I rebuilt it exactly the same as it started out that it might now be OK.