It can be confusing because many leveling compounds are marked as useable on a variety of surfaces including linoleum and vinyl.
Can hardboard be place on top of vinyl tiles.
3 adjust it so that the edges do not correspond with the gaps between the floorboards.
Stir ready to use floor patching compound with a paint stirring stick.
Hardboard is a very poor poor product to use for preping a subfloor.
To properly install a new tile surface you should remove the existing vinyl tile grind down as much of the old tile adhesive as possible and then apply the leveling compound to smooth out the surface for the new tile.
4 loose lay more boards up down and across the room.
2 loose lay the first board over the centre with its long edges at 90 degrees to the floorboards.
It is not a good idea to lay ceramic or stone tiles on suspended upper floors unless you are sure that the joists can carry the extra weight consult a structural engineer for this.
I believe you want to be tiling on something like cement board or ditra not directly over plywood.
I was planning on using 6mm plywood for a solid base for vinyl although i see most websites recommend hardboard.
If you are planning to tile over the hardboard make sure that the rough mesh side is facing up to give more of a key for the tile adhesive.
Fill low spots on the floor with patching compound applied with a putty knife.
Surely ply has better moisture resistance.