Well

I have installed the shower base and because the 3 joists under it are
uneven it is slightly supported on one side.

Now after tiling up to it any everything I think over time it will drop as I
have only wedged a few things under one side.

What I would like to do, is in the gap under the slightly risen side, squirt
some kind of cement to fill the area up that will go very hard??????


The no more gaps filler looks great, but it does not go hard enough to stand
the weight of the base or persons, so what do I do???

If I use a sand cement mix, will it set (ply wood) and what do you guys
recommend to get it in there???

Merry Christmas and thanks in advance for your excellent DIY help??