Christian McArdle wrote:

wattle and daub is very similar to (thicker) plasterboard: Key is the
air gap/cavity, which should be filled with insulation.


Any clue as to a u-Value, though? I presume uninsulated.

err- work it out yourself from plasterboard, tinber and air gap values...

Having lived in wattle and daub, its better than single brick, a bit
better than double brick, but not as good as cavity insulated double
brick...

The killer is draughts.

Christian.