I've taken up some of my upstairs floorboards to install pipes, and am wondering whether it's worth putting some insulation under them before I replace them.
Generally I heat the ground floor of my house, but leave most of the first floor unheated. I notice that the upstairs rooms do get quite warm when the heating is on downstairs.
The floor at the moment is Gyproc ceiling + 20cm gap + 18mm chipboard.
I've seen this "Foil Tec" at Screwfix:
Are there cheaper options available? What do new-build houses use for insulation?