There's an interesting George Clarke one-off tonight on Channel 4 at 8pm, Amazing Spaces Special: 24 Hour Build which focuses on the Welsh tradition of Ty unnos (if you build a home on common ground in an night, then its yours for keeps).
Here's the blurb from the production team:
Inspired by a 600-year old Welsh legend, George Clarke recruits Will Hardie and a team of skilled builders. Together they design a lakeside cabin built using the natural raw materials to be found in the surrounding lakes, hills and valleys near Machynlleth in Wales. They then have just two days to complete all preparations for this epic challenge before constructing the project in a day.