Originally Posted by Tumerboy
Making Normal Maps for modular (tiling) geometry, is pretty much the same as making it for a tiling texture. As long as your edges match up you should be fine. You're worried about seams between adjoining segments, but again, as long as you make your map right, it won't be a problem.
As for the creation process? You can do whatever the fuck you want to. Can you Bake from high poly to NM? Sure!
Hey Tumerboy, to follow up with aeryn's question. Because modular buildings share texture space there are tons of overlapping UV's. I thought if you are to bake a normal map from a high poly mesh, the low poly cage can't have any overlapping UVs. Wouldn't that cause a problem when you pack so many different elements onto one texture sheet?