Stud wall to insulate under single skin window wall

[Kinnectus]

I am looking to purchase a 3-bedroom, 1960's property where one of the upstairs windows is atop an externally cladded, single-skin frame with internal plasterboard and papered inside. The room will be a child's bedroom.

I would like to know if I can safely build a stud frame on the inside, fill it with insulation and then plasterboard/skim, paper/paint as required and install a traditional window sill without the hassle of having to consider removing old plasterboard, vapour barrier etc.?

The property currently has a warm air heating system that will be being removed and replaced with traditional wet system - other than kitchen (taps, washing machine) and bathroom (toilet, taps, shower and plumbed towel warmer), there are no radiators or associated plumbing to any room. I would like to install radiators upstairs to all bedrooms as part of the heating part of this project.

Obviously my main consideration is potential for moisture issues - but if the existing skin is already covered and no existing moisture/damp/cold spot issues, will I introduce a problem?

Any and all advice appreciated.

Thank you

 

[foxhole]

Quicker easier and more effective to just use Celotex straight to wall and plasterboard over , or insulated plasterboard is even simpler .Then add a deeper window board .