Have a look at this image - http://www.themodernantiquarian.com/post/17173 - can you see the roof of anything here ?

That site is mix-and-match archaeological reconstruction. Most of it looks sloppy to me, and the site name is wrong, wrong, wrong. But the roundhouse is very well made and has survived the storms of several winters. The raw materials were a fieldwall, some forestry poles and a lot of heather. There is also a useful method for getting free beers or coffee at the bar nearby ("Will you put this on R's tab, please").

It's called Brigantium - but should be 'Votadinium' - and no doubt Google will respond. On Tyneside there are roundhouses at the Rising Sun visitor centre (1) and Bede's World (3?). I've the thatcher's phone number somewhere. If you were to build a Bronze Age roundhouse instead I could suggest how the courses of stone were laid. The Aberdeen county archaeologist has spent a couple of summers excavating a roundhouse hamlet and has made some startling discoveries.