How to create a fall in bathroom with Hardie tile underlay sheet on top of timber floor?

fredie

Hi fellas, 

We are renovating an old bathroom, which had had timber floors. I’ve layed Hardie ceramic tile underlay on top (ctu) of timber floors. 
What’s confusing is how to get a fall as it’s pretty much flat at the moment. 
do we need to screed it to get that fall? 
can a self levelling compound do a magic to create that fall ? 
Any help would be appreciated 

kind regards 

EricL

Hello @fredie 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about creating a fall in your bathroom floor.

Yes, you’ll need to create a fall for proper drainage, especially around the shower area. A self-levelling compound won’t help here because it’s designed to level surfaces rather than create a slope. Instead, a screed is typically used to achieve the necessary fall.

To do this, you’d apply a sand-and-cement screed mix over the Hardie underlay, shaping it to direct water towards the drain. The fall requirement varies depending on your drainage setup and possibly the rules and regulations of your local council.  

If you are applying a fall for the entire flooring area, I suggest leaving it to the professionals as they will have knowledge and experience to apply the screed properly. I don't recommend doing this as a first time D.I.Y project as any inconsistencies in the application of the screed could cause water to pool on the surface of your bathroom floor. 

Here is a handy step-by-step guide: How To Screed A Shower Base (for a shower cubicle only)

If you need further assistance, please let us know.

Eric