Bungalow Conversion Insulation Help

[richo106]

We are planning on adding another full story onto our old bungalow, the footings are OK and planning is going through (hopefully)

 

The existing external brickwork will be rendered and the new upstairs will be brick (see photo)

The existing bungalow has 70mm cavity with retro fitted blown cavity insulation, it is brick both inner and outer skin. The extension on top will carry on top of the current brickwork so this will have a 70mm cavity also. What insulation would be best to use in the new cavity? Will I have to alter the existing cavity insulation?

Will it be best internally insulation anyway? To satisfy building regs?

 

The ground floor concrete slab will have at least 100mm PIR (most probable floor)

Just trying to look at the best way to internally insulate as I want to try and do this myself (competent DIY'er as electrician by trade)

Is it better to dot and dab insulated plasterboard? Or batten and insulated then plasterboard? I will be taking off the existing plaster to expose brick work etc

All help and advice will be greatly appreciated