On 10 Sep, 10:28, RobertL wrote:
Can anyone suggest how to make the thinnest wall that will meet
building regulations (especially part L) for an external wall?

I am building a oen ground floor side extension along part of the
gable end of my terraced house, but the available plot is only 700mm
wide at its narrowest. *I want to lose as little internal width as
possible.

any suggestions?

Robert

Studding with external skin planks of feather edge boarding on vapour
permeable roofing felt. (Timber or suchlike.)
Between the studding ridgid insulation board.
Inner skin, vapour barrier & foil backed plasterboard.
Studding would probably need to be 150mm to meet insulation
requirements.