Loft room insulation

[svouts]

I want to install insulation in the loft and then finish it with plasterboard. See pictures.

I am planning to add

A. either:

1. 44 x 69 mm battens and 70mm rockwool insulation.
2. 44 x 99 mm battens and 100mm rockwool insulation.

B. Vapour barrier foil.

C. 9.5mm plasterboard.

It will be easier to install 69mm battens and 70mm rockwool, will it be enough?

 

[blup]

I am not an expert but looking at the Kingspan U value calculator, for a cold roof, you would need 125mm of insulation in 175mm rafters and 32mm plasterboard. Is it for habitable space, or part of a longer term plan for a loft conversion?

U-value Calculator (uvalue-calculator.co.uk)

Blup

 

[foxhole]

I want to install insulation in the loft and then finish it with plasterboard. See pictures.

I am planning to add

A. either:

1. 44 x 69 mm battens and 70mm rockwool insulation.
2. 44 x 99 mm battens and 100mm rockwool insulation.

B. Vapour barrier foil.

C. 9.5mm plasterboard.

It will be easier to install 69mm battens and 70mm rockwool, will it be enough?View attachment 267032View attachment 267032

Why? Do you hope to achieve?