Since around 97 % of the volume of the polyurethane foam is trapped gas, the insulation is both low density and extremely lightweight, with a high strength to weight ratio.
The low thermal conductivity of the material also means that lesser thickness is needed than that of most other insulants in order to achieve a particular level of thermal performance, making polyurethane one of the thinnest and most lightweight solutions available.
In certain applications, the weight ratio between the PU solution and other insulation solutions can be 1:6 or even 1:10.