Roof insulation

[marlb]

Hi,
I am removing the ceiling in my kitchen so that I can raise the height of it. I am moving it up by about 500mm. I have building notice etc.
Can any one tell me the calculation to work out how much and how thick
the insulation has to be before I cover it over. BC will see before I cover it.

 

[noseall]

does this mean that part of the ceiling will be raked. i.e. flat top with sloped bits?

 

[marlb]

Yes it is being raised so that it will meet the ceiling in the adjacent room as we are knocking through.