Radoslaw Tober
Hello It will all depend on the material used do insulate the loft now if you can reuse it in the future, also the method by which the job will be done, influenced by the changes to the future loft space and of course - what fallows - is the price. As to the guidance the thickness 220mm- 270 mm applies for new homes any houses over 15 years old thats should be a minimum of 120mm on timer joists 100mm and is limited by the roof spacing and ventilation to allow breathability. Insulation can be installed either at ceiling level or below the roof itself, although the detailing in each case will need to be different. In most cases a ventilation path should be retained above the insulation to carry away any condensation which might affect roof or ceiling timbers.
