cylindical UV mapping

I got a problem with UV mapping my shop. I've tried to UV my walls, but the problem is that they are build from a cylinder, which means when I try to use the cylindrical mapping tool I get a UV mesh that looks nothing like it should. Each subdivision's UV is way too high and too narrow. So I can't create the precise textures I want...

I've been looking around the internet and found no solution. Anyone got a good suggestion??? I've tried to use automatic mapping, cutting the UVs up into the subdivisions and then correcting them...but it takes forever and is not precise enough.