keep in mind, before u go nuts, that the lighting grid gets affected by void. hard to explain, but chase around in cg_thirdperson. if there is a big void somplace, lighting the dynamics will make them 'grey', or null.
so fill the gap, if that happens with an area, with detail caulk.
found this:
http://www.shadowspawn.net/temp/grey.jpg and this http://www.shadowspawn.net/temp/inside.jpg was caused by this:
http://www.shadowspawn.net/temp/detail_wall.jpg
so i just filled it up with detail caulk and it went away. just something to keep in mind when using alot of detail.
of course, ydnar will probably be fixing that too, but don't count on that.