Most solid ground floors being considered for refurbishment will be non-insulated.
Original floor: Solid ground slab with screeded finish. There is some uncertainty about the actual insulation value of non-insulated ground floors. It is very dependent upon the properties of the subsoil. The literature provides values ranging from 0.3 for large buildings to 1.0 for small shallow-plan buildings.The dependence on size is due to the three-dimensional nature of the heat flow.The outcome is that large buildings may have relatively low floor U-values already, and the cost benefit of floor insulation may be poorer than for other parts of the envelope.