Mitch’s Wargaming and Model Making Site has a mini series on making a Saxon house.
The Command Tent has a nice post on how to scratch build a viking A frame house. I’m going to build a couple of these for my Viking/Saxon/Norman games.
Here’s a site with four very nice paper models of 25mm / 28mm half-timbered houses that would be appropriate for a fantasy or medieval town setting. There are “shoddy shops” a “posh place,” a plain half timbered house and a building that is more fantasy oriented. All are in pdf format.