Lifted ground floor roof and built on top.Existing cavity walls 265mm now need to achieve u value of 0.3(up to 300mm cavity now) .Building inspector has suggested using Gyproc Thermaline plus (this is 35mm thick with plasterboard)only trouble is @£30 a sheet its expensive :cry: . I need at least 10 sheets!does anyone know of an alternative :idea: peferbly cheaper :?: would be using 12.5mm board on walls.
Try looking at the websites of Kingspan and Celotex. They will be able to calculate your u-values for you on a 65mm thick board. These producets are also quite expensive so be warned!
