tamarmole wrote:Slightly concerned about the poles, they don't sound like they are designed to be load bearing - if the walls are not thick enough the poles will buckle when loaded with catastrophic results.
I think you are correct. 2" sounds too small a diameter. The pole in the above picture is 3" and around 20' tall. It actually is supported in the middle by contacting the rock shelf about half way up. I made a PVC ladder for another cave that is 18' tall and made with 3" pipe with 1 1/2" rungs. If I was to build one 30'-40' in height, I'd step it up to 4" pipe and connectors. One way I was able to keep the flex down in the PVC ladder was to space the rungs at 18" instead of 12". There are two supports built into that ladder also, that contact the wall. I'll see if I can find a picture of it.
If any of you are coming to the 2014 NCRC training in Colorado, you will get to use these ladders and see for yourself how they are constructed.