i am ready to insulate the loft before i board it out etc ive taken out the old insulation so going to re-insulate it entirely..ive already got some top up insulation from b&q from a £3 a roll offer,is this sufficient insulation if i lay it in 2 lairs ? or should i have a different base insulation of lets say better thermal properties layed down 1st..if so what should i purchase & from b & q i presume will stock it..cheers again (think i have in excess of 200mm depth in loft..steel frame house)