Another insulation query

[Ando]

Hello again - looking for some guidance for how best to go about insulating the front part of our living room that has the sloped roof above it.
Is it a case of striping the plasterboard ceiling from inside and then using rigid insulation boards (PIR etc)? 
The next question is how to tackle insulating the dormer window - which is our bedroom? Fairly certain all currently uninsulated. 
 

Will be getting tradesman in to do this work - but would be great to have an idea of what to ask for in advance of speaking to them. 

The living room ceiling is priority despite our growing list of jobs around house as had water leaking in from a dodgy roof tile midweek during torrential rain - so aiming to sort both at same time.
 

Any advice greatly appreciated!  
 

 

 

[ProDave]

I would tackle all of this from above.

 

Re the living room ceiling, that will be what is known as the eaves or coombe space.  If there is a trap door on the bedroom wall below the window, then you are laughing.  If not, cut a section of the plasterboard wall out and make one.  That will enable you to get in and see what is what, see what insulation you have, how well it is fitted and what you can do to improve it.

 

Same for the dormer, plasterboard off and see what is there.

 

Expect to strip and re board the entire front wall of the bedroom to do it properly.

[Ando]

Thanks. There’s no hatch but space to easily make one. So once into that space to insulate is it a case of following the same principals for how you would insulate loft space and suspended timber floors? Vapour control layers / insulation / breathable membrane etc? 

Does the sloped section inside the bedroom all need striped and redone also? And I’m assuming the ceiling under flat roof part is a bit more complex? 
Apologies for the rookie questions - trying to get my head round so many different aspects of this stuff!