I'm insulating, plaster-boarding and skimming the sloping roof ceilings in my bedrooms. It's only a small area where its sloping but I'd still like to hav insulations.
I am aware of the 50mm air-gap recommend in the joist to allow for proper ventilation.
My dads plan is cut kingspan or their equivilant and slot the inbetween the rafters. Allowing a 25mm air gap and then boardboard plasterboard over the top.
Personally i think it's risk, and believe its easier (if not more expensive) to buy special insulated kingspan plasterboard and scew it straight to the rafter.
I am aware of the 50mm air-gap recommend in the joist to allow for proper ventilation.
My dads plan is cut kingspan or their equivilant and slot the inbetween the rafters. Allowing a 25mm air gap and then boardboard plasterboard over the top.
Personally i think it's risk, and believe its easier (if not more expensive) to buy special insulated kingspan plasterboard and scew it straight to the rafter.