I'm finishing up adding a wooden ladder to my price table. Sounds simple, right? Have a look at my thought process below, to see what I think about when I add something to the table.
I'm modeling each rung as a carved cylinder of diameter 1.5 inch and length 1 foot.
This is just a plain old straight ladder, so the side pieces are two long planks. I've got them here as 17 feet long each, with width and depth both 2 inches. Distance between rungs is 1.5 feet, so that's ten rungs plus a foot of extra at the top and bottom.
(If you're Alexis, sit down for this one.) I've only got one type of lumber in my game. Its density is 40 lbs per cu. ft. I'll concern myself with multiple types one day, but not now.
Each cylindrical rung: cubic feet is (pi * height * (radius ^ 2)). Each plank cubic feet is obviously 17 * (2/12) * (2/12).
Total the volume, multiply by density of lumber, and she comes out to 42.69 lbs.
Now let's talk gameplay concerns.
If wooden ladders are this heavy then that's just incentive for the party to carry around a rope ladder or climbing ropes instead. On the other hand, I'm making some sorely-needed expansions to the climbing rules so that a wooden ladder is the safest way to climb. A rope ladder will still sway as you go, meaning there's still a skill in climbing one (though it's not as hard as a rope.) Furthermore, if there's nowhere to toss the support hooks, you're going to have to spike it like a rope at the top; in that case you can't climb somewhere you haven't been to the top of. A wooden ladder has no such restrictions.
I originally wrote this post as asking for a sanity check on my calculations (and please do offer criticism.) I was worried that it was coming out too heavy. But now that I've thought out loud about how it fits into the climbing-equipment ecosystem, I'm actually fine with the weight! If the party wants the most reliable way to climb they're going to have to cart one of these suckers around.