How to insulate ceiling under flat roof?

[beefster]

I am looking to convert a side extension / store room with flat roof and no heating into a living space / office.

Have checked the roof and no insulation at all. What would be the best way to insulate the ceiling which is currently plasterboard.

Just putting in a new heating system in and want to add a rad to this area which was a farm shop on side of house.

 

[beefster]

Anyone...

 

[mointainwalker]

How deep are the joists carrying the plasterboard ?

 

[beefster]

9 inches. Maybe a little more?

What are you thinking?? Kingspan between joists??
Was wondering about a vapour barrier? Where to put it?

would this be right working down.
Felt
roof boards
air gap - poss add breather vents in each run. None at present? needed?
insulation board
re - plastr board.

Where doeas the vapour barrier go?

 

[noseall]

What would be the best way to insulate the ceiling which is currently plasterboard.

Either add a warm deck system above the joists or, if you can ventillate, use insulation between and below the joists.

Any vapour barrier will need to go directly behind the plasterboard.

 

[alittlerespect]

Hi

Easiest solution would be to 'stick n fix' 100mm of PIR insulation to the top of the existing roof and re-felt (asssumes that you have enough of an upstand).

May require the flashing to be raised.

Otherwise job done and not a lot of mess!

Regards

 

[^woody^]

Just bung 9" of quilt between the joists and then use foil backed plaster boards. Old skool

 

[mointainwalker]

woody

Not old skool but simply the easy, cheap, labour-saving , intelligent method.

Exactly what you look for in a solution.

 

[beefster]

Just getting around to this part of the project.

Queries.
I assume foilbacked boards act as vapour barrier. What do i do at joints to seal it?

Re 9 inch quilt, How best to hold it up in between the joists before boards go on?

Ta