[Chris Sweeney]

I will be tiling a bathroom floor. The 3/4" plywood sub-floor I will be working on has a few low spots in it. Now, I've used floor leveling compounds before, but an old contractor friend of mine said I can just use some sand to fill the low spots before laying my cement backerboard down. Has anyone ever heard of this, or is it a bad idea? Thanks!

 

[joecaption]

So you want to lay down a non compactable material that's sure to flex?
How low are these low spots?
What's there now for a subfloor?

 

[Chris Sweeney]

So you want to lay down a non compactable material that's sure to flex?
How low are these low spots?
What's there now for a subfloor?

The low spot I'm concerned with is basically a 1/4" valley over the span of about 3 feet. Subfloor is 3/4" plywood.

If I can't use sand, I'll just go back to using floor leveling compound; I just wanted to see if anyone else has ever used sand for this purpose, since it sounds so much simpler. I thought it probably sounded too good to be true though.

 

[joecaption]

I would install the 1/4 tile board in a bed of thinset, use non gypsom floor leveler to fix that low spot then set the tile.