Hi My kitchen has a uninsulated Flat Roof. Would it be possible to fix Kingspan Kooltherm K17 Insulated 50mm/12.5mm Plasterboard sheets to the ceiling over the existing plastered ceiling or any other suggestions? I would like to insulate it from inside as the felted flat roof is in excellent condition.
Flat Roof Ceiling
- Thread starter taxi1161
- Start date
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Yes the thicker the better.
And how are you going to deal with the airspace venting between and/or the resulting condensation?
I was under the impression it had an inbuilt vapour barrier to combat the build up of condensation.
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Hi thanks for all the replies. I have now taken the plasterboarded ceiling down and because I have got 350mm roof space (70mm above the joists) I have decided to fit 270mm of Rockwool between joists leaving a good airflow above the insulation and then finish with 12.5mm plasterboard.Two Questions will I need a moisture barrier (if so what type)and how can I hold the insulation in place so i can replasterboard the ceiling ?
If the roof space that is left has no vents then I would recommend you put some in, if that does not seem an option then use foil backed plaster board.
Hi catlad So if I put in vents I can just use standard plasterboard?
You are over-simplifying what is not a straightforward yes/no answer.
When dealing with problems that lead to condensation, you need to do the work as robustly as possible.
Every joist run will need venting.
You will need an air gap above the insulation.
You will need a vapour barrier.
When dealing with problems that lead to condensation, you need to do the work as robustly as possible.
Every joist run will need venting.
You will need an air gap above the insulation.
You will need a vapour barrier.
Hi As I said in one of my posts I have at least a 70 mm space above my joists. The roof deck is mounted on 70mm blocks which are screwed to the joists which means the air flows freely across all the joists. At the moment air gets in to the roof space through a air brick in the cavity wall. Anyway I am going to put some vents in front and back and probably
a moisture barrier.
Just one last thought, When I had no insulation the warm air from the kitchen was going straight through the plasterboard and hitting the cold underside of the roof deck and I never had any problems with moisture/damp.
Thanks for all your help.
a moisture barrier.
Just one last thought, When I had no insulation the warm air from the kitchen was going straight through the plasterboard and hitting the cold underside of the roof deck and I never had any problems with moisture/damp.
Thanks for all your help.
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