Hi there. This may well have been answered/addressed in other posts, so apologies if so.
We are designing an addition to our Melbourne home. Approx 70m2. Due to flood overlay, new build has to be approx 800-900mm above ground level. Soil is reactive clay.
Initial thoughts was to use a suspended concrete slab to enhance passive thermal properties and obtain greater thermal mass. Current design sees winter sun hitting the floor during the central part of day via high northern windows in a skillion, while summer sun is minimised due to orientation and eaves. Otherwise, structure was planned to be insulated timber.
We've been told that cost of a suspended concrete slab is significantly more than usual timber floor structure, owing to height of slab and soil type, and flood overlay issue. Can anyone comment on the cost differential? What is the thermal delta between the suspended slab and insulated timber flooring? If a slab is cost prohibitive, what options do we have to maximise our winter heat retention in timber floor?