Can I use an alternative underlay instead Warmup’s underlay?
Yes – but the underlay must be soft, 6mm thick and be suitable for use with underfloor heating systems.
Rigid underlay boards are not suitable and may result friction damage to the heating element especially in high traffic areas. A soft underlay will provide a cushion and protect the heater from damage.
If installing onto an un-insulated base an underlay without insulation properties will not create a barrier to stop downward heat loss.
Warmup always recommends the use of insulation to increase the energy efficiency of the system.