Would vinyl reinforced concrete be okay to use as an underlayment for carpet? I have a basement room that has an uneven floor. There is as much as a 1 1/4 inch variance within 5'. The high area runs through the middle of the room so I was planning on just leveling the half that is opposite the door and letting the original floor gently slope toward the door as it is now. This is the only room in the basement that is not yet finished. I'll be pouring about a 6' x 11' area a median 1/2 inch thick, the thickest being 1 1/4", but I read that this type concrete should only be used for small patch repairs. Thanks for your help.

roundmonkeylover

Vinyl concrete...? It sounds like you're trying to level off your floor, so i guess you want a levelling screed. Sand-cement screeds should be a minimum 2" thick so you should try a pouring screed - have a look at Floor Underlayments by Hacker Industries Inc. - underlayment - 800.642.3455 they have a range of products (and a selecter chart) which i think is are what you're looking for.

Good luck.