Bay window area insulation

[Ay8452]

Hi guys,

 

The bay window area of my 1930s house is in a bad state. The structural engineer has had a look and recommend replacement with timber (first floor) and the ground floor is fine (masonry). It's all part of a renovation of the house and we are getting new windows too.

 

I've recently had the loft converted - am I ok to use a similar insulation spec to the dormer walls? This is what I had in mind from outside in 

 

 

Tile cladding (Rosemarie tiles)

 

Vertical softwood timber battens. Provide PVC vent with insect mesh at all sides of cavity.

 

Horizontal battens with top edge chamfered to encourage water run-off. 

 

Breathable roof membrane.

 

9mm external grade OSB.

 

OSB to be fixed to studwork.

 

PIR insulation between studs with 40mm cavity for ventilation external side of stud frame.

 

PIR over studframe to stop cold bridging taped to act as VCL

 

Plasterboard and skim.

 

Is that sensible? I was also thinking of adding EWI to the outside of the house - but this wouldn't quite like up with the bay window insulation.

 

 

Thanks!