We've moved into a 60+ year old home with a pool and falling apart pool house. The pool house is just about torn down now and we want to build a pergola on the existing 18'x18' slab, with a pre-built shed taking up 4' on one edge (18'x14' pergola). Problem is that the whole house, pool and slab are oriented NE to SW (almost exactly) and we want maximum afternoon shade here in the Richmond, VA area. Everything I've read says to orient the slats north to south, but that would mean putting them at a 45 degree angle to the frame and rafters. Are there any reasons NOT to do this?