For one of my upcoming campaigns the PC's are going to be stranded with about 57 commoners. I wanted to know what kind of supplies they could expect from the commoners and when, assuming the commoners are able to get a Thorpe going. My math might not be perfect but I think it will be close enough and I'm open for corrections.
I figured about 1/3 of the 57 people would be busy gathering supplies, such as food, water, flint and other tool supplies and maybe even metal ores. And eventually working on most of the planting and farming once that is started, or doing whatever other jobs are necessary. so that leaves me with 38 people spending the majority of their time raising houses.
I decided to measure when the Thorpe is officially established will depend on housing, IE once they have houses they live there. But first, tools to build the houses.
Lets assume one guy made his living either making tools or as a black smith and is familiar with tools. He could easily have 4 ranks + 3 from skill focus + 2 from a skill affinity and maybe another 1 or 2 from synergies that's 11 (or 9 if you don't know what I mean about skill affinity). I think I could make him above a +12 if I wanted but I'm thinking this guy is NOT a specialized tool making expert so I'm only going to give him +7.
He probably has an assistant (so that's 2 of the 38 people) giving him +2 for assistance.
Starting with improvised tools (-2) and having nothing to start with, (-2 circumstance) I think can be made up by whatever this guy and his assistant had on them while traveling and the +2 circumstance bonus of knowing the whole village is dependent on them. Survival can be a good motivator.
We still have 7 skill and +2 for assistance. Master work tools have a DC of 20 so he needs to only roll an 11 to make 280 sp a week. It takes 2 weeks to make his first set of master work tools. (or if he needed to make some basic tools first he could have) That's 2 sets of masterwork tools a month, helping the remaining people build houses. They can always share tools until more are ready.
Building the Houses
I have 36 people left making the houses. I'm assuming most of them are not specialized in making houses so lets assume they have a total of +4 from relevant skills and synergies. Such as from Craft (Wood Working).
Even though each person will be doing work by themselves they also each have 35+ other people to ask questions and get some assistance. So that's +2 from assistance and another +2 from the masterwork tools being made. And considering they are all excited to make a new community and equaling afraid for their lives that's a +2 circumstance bonus. 4 + 2 +2 +2 = +10
I can assume an average roll of 10 so that's a total of 20 for their craft checks and I believe a house isn't typical DC10 nor is a log cabin a Complex DC 20 so I'm going with DC 15. 20 * 15 = 300 SP per week.
Now assuming 1/3 of the Thorpe is married to another third of the Thorpe at most you need only 38 house for the 57 people if that. Remember this isn't counting kids but they live the same households anyway. Each csimple house costs 10K silver so that's 380K
The 300 SP a week is 1200 SP a month per person so 43.2 K a month. 380000 / 43200 = 8.79 so about 9 months later a fully built Thorpe. Even if they spend more their time helping set up farms, I doubt they really need that many houses.
If you want to help me correct my math feel free but please don't trash talk 3.5 or my thinking just because you think crafting is broken. Anyone who thinks commoners cannot support themselves should read Justin Alexanders "D&D: Calibrating Your Expectations"
Also remember a single person specializing in survival can easily feed 5 other people. And 19 medieval frontiers man will feed the other 38 just fine.