I am in the middle of redoing my basement, new drywall walls. ceiling and electrical, the house was built in 1955 and the finish basement was done around 1970's, the floor has 9"x9" tiles. The first time i just put wall to wall carpet over the tiles. This time I am going to put a new carpet down and i was told i should skim coat over the existing tiles then add felt then carpet. I have no idea what to use for skim coating. i have three room about 13'x 13'. i was thinking of adding wood floor for my office and the rest of the rooms wall to wall carpet. Is this a easy project to skim coat over the existing tiles?

Leveling involves a specially designed cementitious product that dries quickly and is sandable. You mix the product with water or a bonding agent, sometimes both. Once mixed, you would apply using a hand trowel. You need to work quickly, because it dries quickly.

If the tile has a glaze, you may need to sand the glaze in order for the leveling product to adhere.

In most cases you can just put the padding over the tile without the need to level. Unless the tile has a high profile that would transfer through the padding a carpet, I would skip the leveling process.

so are you saying i dont have to skim coat the foor? i can just add the felt then the carpet?

Unless the profile of the tile is exaggerated where it will show through the padding and carpet, I don't think you need to skim coat.

Depending on the thickness of the carpet and padding, the padding will conform to the valleys and you will never see or feel any bumps. However, the cheap solid foam padding will probably transfer the ridges.

You can skim coat if you want, but it may not be necessary.