A thermal insulation structure for a substrate for use subsea, and a method of providing a thermal insulating structure. The structure comprises: an inner layer and an outer layer. The inner layer is the reaction product of a first part and a second part, wherein the weight ratio of the first part to the second part is from about 15:1 to 1:1. The first part comprises any of alkenyldialkyl terminated polydialkylsiloxane, alkenyldialkyl terminated polydialkylalkenylmethylsiloxane or mixtures thereof, which will individually or collectively have a viscosity of from 250 to 10000 mPa·s at 25° C., and a hydrosilylation catalyst. The second part comprises a mixture of organohydrogensiloxane having two Si—H bonds per molecule and organohydrogensiloxane having at least three Si—H bonds per molecule. The outer layer is the reaction product of a first part and a second part, wherein the weight ratio of the first part to the second part is from about 15:1 to 1:1. The first part comprises any of alkenyldialkyl terminated polydialkylsiloxane, alkenyldialkyl terminated polydialkylalkenylmethylsiloxane or mixtures thereof, which will individually or collectively have a viscosity of from 250 to 10000 mPa·s at 25° C., and a hydrosilylation catalyst. The second part comprises organohydrogensiloxane having at least two Si—H bonds per molecule and alkenylated MQ silicone resin, wherein said M group comprises at least two Si-alkenyl bonds per molecule.