Can I lay SupaSoft on top of the existing insulation in my loft?

Yes. The amount of additional insulation will depend on how much existing insulation is in place and what condition it is in. For instance if the insulation is in very poor condition we would recommend adding 250mm of SupaSoft on top. However if it is in very good condition, add sufficient SupaSoft to achieve a total insulation thickness of 270mm. Check under and around existing insulation for any signs of damp or water damage.