A little blinded by science here. I'm sure there is plenty of reading to be done in this area.
I think your last comment on cost and state of rest of house is important here. I will likely settle with fibre glass rolls only and try to keep the existing insulation in place where possible...
Thanks for the reply, Tomfe.
The rooftop is a continuous stretch along the terrace of houses so adding to the top of this is complicated with party boundaries. I know that warm roof construction is recommended but for this reason I would prefer to pursue options to tackle this from underneath...
Hi DIYnot,
Wonder if I could call on your expertise. I have 1973 house with flatroof with asphalt on tonge-in-groove construction. Under this is an 11" high cavity with no ventilation between rafters. There is 20mm polystyrene insulation resting on plasterboard with the obligatory artex finish...