Hello I'm building a shower stall in my basement, I think in the process of getting information I missed something now I have a misstake that needs fixed. HELP

I have 2x4 studs
insulation between them
no vapour barrier
1/2 wonderboard (cement board)

how can I make this work without taking the cement board down and starting over?


Thanks very much guys

Cover the surface of the CBU with a waterproof membrane.
Could be any one of the following:
Schluter Kerdi
RedGard liquid waterproofing
Mapei AquaDefense liquid waterproofing

There are lots of other really good products available but not so easy to get depending on where your located.

Any particular reason why you can't remove the backer board and put up poly?

Thanks Randall

I already have the base in and sloped to the drain, the waterproof membrane will stick to the ceiling? and then the tile adhesive will stick to the waterproof membrane fine?

Yes it will stick.
Tile adhesive needs to be a modified thinset.

Thanks very much Randall, after going to the store and seen how much that stuff cost I thought I have poly at home and time so down came the boards and up went the poly.

It was good to reinforce my earlier thoughts of never using cement board again.

Thank again

Make sure you can overlap the poly onto the liner material, otherwise the poly will be useless. Moisture needs to drain to the liner material.