Well I'm finishing up my sub floor after what seems like forever... Half of my room will be carpeted so I didn't really care about flatness on that side. The other half of the room will have laminate on it so I've been mulling over my options. This is an old basement so there's not much for headroom. I've already installed platon over all the walls and floor and now I'm trying to decide on what sub floor to put in that area. The problem is that the floor is by no means flat. The variations are small enough over most of the room though that even a thin osb sub floor (7/16") would be enough to correct it. I was even leaning towards (3/4") osb to be absolutely sure. But here's the rub... The corners of the basement are raised almost 3/4" or possibly more. I'm sure this made sense when the floor was poured. I mean if there was ever a water problem it would drain to the center of the room and away from the walls. But this now leaves me trying to adjust for this. My first thought is to lay down 3/4" osb sub floor like I was planing and cut the 2' from the corner. This would make the rest of the sub floor lay flat. Then I could caulk the edges of the triangle I cut out and pour in some kind of leveling compound up to the sub floor level. One problem with this is that since there is platon underneath, normal cement based leveling compounds would crack and break up because of possible movement. Does anyone have any other creative ideas or know of any semi flexible leveling compounds? Thanks! Oh, And here's a picture of what I was trying to describe with the corner cut:
