What kind of primer do I use with ultralight?
Warmup Insulation Boards – Ultralight
Primers help encapsulate dust to improve bonding with the thinset you’d apply to lay the boards. But on brand new or clean subfloors this may not be necessary. When in doubt, consider a solvent-free floor primer like Ardex P51 or Mapei SM. If your subfloor is not level or has a lot of residues, such as glue remnants from an old vinyl floor recently removed, you may need to apply a thin coat of leveler to smoothen the subfloor in preparation for your project.
For full installation instructions, visit the manual or view the below installation video.