https://www.medievalists.net/2025/11/how-carpenters-built-medieval-england/?utm_source=gravitec&utm_medium=push&utm_campaign=Push+Notification
Wood you believe it...
Although the proportion of carpenters has doubtless declined, the trade seems quite similar now. We're having a new door made at the moment about 5 miles away (though we could have chosen a small joinery factory half a mile away). Our joiner does work around the area but he also goes off on contract further afield. Seems a common model in the building trades.
Going back to the Middle Ages, you'd usually find carpenters amongs the trades in the train of a medieval army. Never new when you might need a siege machine built or a bridge rebuilt.
Also a lot of people in a peasant society will have tools with which they can do basic woodworking, and have basic experience. It probably wasn't difficult to pick up useful labourers on a big project with a few good carpenters to oversee it and train those showing any aptitude up a bit on the job