Abstract: A method of building a structure on a substrate, said method including the steps of providing on the substrate a support arrangement capable of adopting a first, substantially rigid state whilst the structure is being built thereabove, and a subsequent, second state permitting the accommodation of movement of, and/or forces in, the substrate (e.g. due to heave). The support arrangement comprises fluid confinable means which, in the arrangement's first state, confines a fluid therein to a first space and is operable (via said fluid) to support the structure or at least parts thereof above the substrate, and which, in the arrangement's second state, does not confine the fluid and is either in a reduced space or is readily compressible to a reduced space by said movement and/or forces.