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

I am working on the same problem. My verbal discussions with BCO (not
been on site) suggest that I can use plasterboard, vapour barrier, 120mm
stud (with 100mm Celotex or equivalent infill)external board, breather
membrane and am planning to use Delta-PT membrane with screed to finish.

I await to hear other suggestions.

Paul R