Where best to insulate

[jassdhali]

Guys,
Ripped old old plasterboard from 18 year old extension as I am refitting the kitchen, have found a small layer of fiberglass insulation and absolutely nothing in or on the rafters.
Would it be best practice to insulate rafters, I was thinking 100mm Celotex in between the rafters & 50mm all over after that (Warm Roof Setup).
Or would I be able to do something similar but do so to the ceiling joists in a similar fashion?

Thanks for your help

 

[tony1851]

Why heat the roof void? Better to insulate the ceiling ony, and make sure there is sufficient ventilation to the roof void.
Strictly, this is a Building Regs matter
(Incidentally, what you appear to be describing would not be a warm-roof set-up).

 

[^woody^]

Don't insulate rafters unless you are making a room up there. Insulate at ceiling level

 

[jassdhali]

Cheers gents