Good morning,

Is is ok to apply Henry 549 featherfinish to the top of that plywood underlayment that I mentioned? I have a joist in the middle of my house that sits slightly higher than the two beside it so there is a small hump through the kitchen. If I place the middle of my 6ft level on the hump and push down on one end of the level, the opposite end of the level winds up being more than 1/4 inch above the floor.