Thank you for your great question. We custom make each ship ladder. Most of the ship ladders we make have a max. tread run of 5" (the tread is 5 1/2", but there is an overlap from tread to tread). Going up 8' can be up to 11 risers @ 8.72" = 11 treads (top tread flush with upper floor) so the total stair length (horizontal distance) from the face of the header to the nose of the bottom tread is about 55". It is more common to use 10 risers @ 9.6" in this case, and if it is a fixed ship ladder with the top tread down 1 riser, it would have 9 treads with a total run of 45". That said, we can make ship ladders with nearly any tread run. Some clients have limitations that, as an example, could require a 3" tread run (30" total run). If you require a 1 directional wall sliding ship ladder the stringers are normally made of 5/4"x6" select grade hardwood (typically red oak, but other species are available) so the ladder would have a minimum depth of about 7" when not in use. Please call (845-765-8600) or email info@acadiasstairs.com us to discuss further. There are many options for layout and materials.