I'm planning on building a maintenance access to the main roof on my building and instead of using a pull down ladder I want to install a permanent "staircase." In order for this staircase to work it needs to be steep -- much like some staircases in Amsterdam. The rise of the staircase is around 10' and the run is 6' which makes this violate standard building codes but since this is strictly for maintenance access to the roof I think this might be OK. I've been googling the net to figure out how the dimensions used by the dutch for their steep staircases and can't seem to find anything. The typical max for US building code (as far as I read) requires a max step height of 8 1/2" with a 9" tread. This won't work in my situation. In order for me to figure this out mathematically I'd like to know how I can get this staircase steeper in order to reach the landing.
Does anyone know of a resource (book or web site) where I can learn how to design this including acceptable non-standard dimensions? I read about those alternating step steep staircases and I'd rather go with a regular straight run. I could get a pull down ladder which would be even steeper but those ladders are kind of cheezy and I think I can put in a more permanent structure that would be less steep and look nicer. Right now I'm just planning the project and hope to start building in January and opening the roof next April.
Ironically I was just in Amsterdam last month but forgot to bring a tape measure.