This mod adjusts how much carpentry skill is required to plan buildings, in the properties file is 1 simple value to adjust skillfactor this is a whole integer, so 2 or 3 or 4 etc. basically times your carp skill by this. So a 13x13 plan would normally require 52 wall + 169 tiles = 221, obviously impossible with default, make the skillfactor 6 and you could plan it at 37 skill. Extreme example obviously but that is how the factor works. Default value is set at 2, halving required skill.
Also added a factor adjustment for planning bridges, pretty much same factoring as building, 2 means doubles the skill as far as calculations go for length, also halves the minimum skill needed, ie brick needs 30 mason, 2 factor means you only need 15 mason.
Download mod: https://1drv.ms/u/s!AjnBltNOSFjCgj_Jz3qiuOh1jjmD