func_ladder
This page explains how to make a ladder in a Counter-Strike map with Hammer. To make a ladder correctly, you need three parts, as shown here:
The texture on the visible part of the ladder should have a name that starts with {. These have blue parts which will look clear in the game by setting it to
Solid/255 as above.
Making a ladder with these 3 parts will block players but allow bullets and grenades to go through.
Visible Part: looks like a ladder, but is not solid at all, and does not let you climb.
Solid Part: invisible, but blocks players from moving through.
Climby Part: invisible, but makes it so you can climb here.
