What are the most common areas of your house hold? Look at areas that you spend the most time in. (Bedrooms, bathrooms, Kitchen and living area).
Remember that open plan areas will require more heating than rooms like bedrooms..
When underfloor heating is installed in kitchens or bathrooms the element wires are double insulated or protected by an earth leakage circuit breaker, this is a SABS wiring code. This will make your underfloor heating safe to use in areas where water could be present.
Your thermostat is primarily used to pre-set the timing of the underfloor heating at various intervals of the day / night, this will reduce the cost greatly as the underfloor heating will not be on 24hrs a day. It will also read the ambient tempreture of the room and regulate heat as pre-set by yourself, this will leave you feeling comfortable and warm..
Your underfloor heating is installed directly beneath your flooring, so there are no exposed wires. In areas that are prone to water, the underfloor heating is protected by double insulation and earthed for your protection.