(Also see Even, Flat and Level)
An easy way to determine how much leveling is needed is to place a carpenter’s level on a long straight edge and then measure the space (depth) between the straight edge and the substrate — this will pinpoint the deep spots and help you to estimate the need for leveling in the lowest areas of the room.
A self-leveling underlayment, such as MAPEI’s Ultraplan 1 Plus, is a pourable product that helps correct a substrate that is out of level. Self-leveling underlayments require very structurally sound, solid and stable substrates. Because self-leveling underlayments have short working times, it is a good idea to have at least three people working together when pouring a self-leveler — one to mix the product, one to carry the buckets and pour out the self-leveler, and one to spread the self-leveler and guide it into the desired areas as it is poured.
A primer, such as MAPEI’s Primer T, is always required when using MAPEI’s Ultraplan 1 Plus.