Can you use a different underlay to the Floorify underlay?

Yes, you can. But be aware that Floorify underlay has been specially developed for combination with all Floorify rigid vinyl floors. All of the properties of Floorify rigid vinyl floors that we mention have been tested and measured in combination with this Floorify Comfort underlay (thermal resistance, impact resistance, sound absorption, etc.). 

In addition, Floorify underlays and the Floorify Performance underlay in particular the perfect underlay for underfloor heating.

If you opt for a different underlay and it causes damage to the floor, the extended warranty that Floorify extends for its products will become void.