All wiring and plumbing for the ground floor is now complete; even the in-wall toilet tanks have been installed. After having removed all materials from the ground floor and a thorough cleaning, we are ready for the next step: PU foam spraying. Traditionally, radiant heat in-floor installers use hard PU foam squares or sheets that interlock with each other. These sheets provide the insulation required between the concrete slab and the hydronic piping. The drawback with the hard PU foam sheets is that they need to lay on a flat surface and therefore in our case, we would have had to pour a sub-layer of concrete to embed all wires and pipes and level the surface to receive the hard PU foam squares. Unfortunately, the architect plans had not taken into account this extra layer of concrete.The option was to either lower the suggested height of the PU insulation or to look at other solutions such as the sprayed PU foam.

Before spraying the PU foam, the contractor had to protect all the walls, windows and ceilings as the foam particulate tend to fly all over the place and easily cling on to glass and wood. The foam was sprayed in several layers to give it time to expand and harden. The following day, the foam was sanded and levelled to a consistent 9cm thickness. The foam, once hard, can withstand a weight of 20 tons per square meter.