Check the floor with a straightedge to find the low spots. You can find high spots in the floor because the straightedge will rock on top of them like a teeter totter. As you work your way across the floor from high spot to high spot, the dips will be clearly visible. Mark them with a pencil.
Put on a pair of safety glasses and a dust mask. Dump a bag of dry-mixed self-leveling compound into a bucket and add water, according to the manufacturer’s instructions. Use a drill with a paddle attachment to blend the mixture to a soupy consistency.
Pour the self-leveling compound onto the low spots of the floor and spread it around with a flat metal trowel to ensure the mixture completely fills the areas. For best results, pour extra compound into the low spots then smooth them over with the straightedge by pulling it across the high spots to force the excess away from the low areas. Let the compound dry for 24 hours then install your Pergo floor.