That would fall more in line with a "special case" item, since it's not a piece of adventuring gear, why would the game system classify it with a level?
A house would fall well outside of the scope of the crafting rules imho. Instead you could call for a "craft" check that is not the crafting activity, and set a DC based on the difficulty of the buildings to be made. For time scale, figure at least a few weeks (and that is frankly VERY quick) for rapid construction on up to a few months of regular labor to rebuild a town.
In reality it could take 6 months to a year to really make any impact in rebuilding a town from scratch, unless the razed town didn't lose any meaningful amount of manpower to pitch in and help.
I would probably approach this as a non-check activity honestly, figuring the amount of time available will allow you to correct minor mistakes, especially if there are experienced tradesmen helping, and just deduct the time you decide is reasonable from downtime.
That would fall more in line with a "special case" item, since it's not a piece of adventuring gear, why would the game system classify it with a level?Because acquiring and building a stronghold is a common trope of fantasy RPGs, where characters can eventually become Lords, Princes, and Kings.
There have been Stronghold Builders Guides in many editions of similar games. By assigning a level to, say, a Castle, it generates the idea of "ok, so this is the level at which I can give them a castle".
Sure. But that is not something that pathfinder does that I know of, so why bother? For a pc homebase, it's far more efficient for the GM to fiat into existence such a structure, with input from the party.
So again, since the system doesnt really ask you to build a house 99.9% of the time, why would it classify a house with a level?
Sure. Feel free to read through those rules. Largely, you are picking bonuses for your kingdom using special points you get from loot/ for gold. BP I think. Been a long time since I looked at em.
But the task that you describe is very different. If you want, you and your GM can come up with a complex set of rules to intricately simulate building a house from obtaining materials to laying foundation to putting up walls and amenities etc... or your gm can give you a craft dc and extrapolate out what happens, since it will be happening in a long and drawn out time frame.
Like I said, largely the task you are taking on is too large and happens over too long a time for one single check to cover reasonably. So forego the check and assume that your character is competent if you are trained in Craft. Or that there are skilled craftsmen in the village.
If you are looking for more detailed rules for building a village, I'm sure you could find some from one game or another to adapt. But the PF2 crafting rules simply don't handle building a village as is.
Unless you and your gm agree that crafting a house in 4 days is reasonable. In which case, use the crafting rules as is, and have your gm assign levels to various houses based on their speciality. A blacksmith's shop is going to be more intricate than a standard house for example. So if a standard house is lvl 0 or 1, the shop might be 3 or 4.
Really the lack of a "standard" rule in this case is more freeing. Your gm and you have all the room in the world to make this activity as complex as you'd like. Go ham.