Is my bathroom floor ready for waterproofing?

[tom138]

Hi there, I just got new floor laid in the bathroom (James Hardie Secura on timber frame) and just wondering if I can get some advise whether these gaps are acceptable and ready for waterproofing. Here is the gap between the shower recess and rest of the floor (~10mm)

And here between the floor and bottom plate (19mm widest point):

I’m planning to sheet with villaboard so that’s 6mm less gap but still…

The tiler/waterproofer says the gaps are too big and the carpenter/builder says this is build to code and that the tiler is not worth his salt if he can’t deal with it. I’m not sure who is right but it does seem like there is no reason for gaps like that… any advise is much appreciated!

[tom138]

Thanks @MitchellMc, great idea! I couldn’t get any timber strips as there was insulation in the way so I used a 4.5mm FC sheet as backing

Frustratingly, partly due to a inaccurate measurement (no matter how much time did I take and how many times did I measure) and old out of square/level frame, I’ve ended up with quite a big gap between wall sheet and ceiling in one place (about 1.5cm):

Is this within acceptable tolerance or is it too big? Would you still recommend Sikaflex? I am planning to install simple timber coving/cornice that should cover the gap.

Last question - JH recommends to use the James Hardie Base Coat 4kg for villaboard but this product unavailable in all stores close to me with unknown availability date so can I use Gyprock CSR 3kg Wet Area Base Coat instead? It says it’s also for FC sheets. 

Thanks,

Tom

[JacobZ]

Hi @tom138,

While not ideal, as it's not James Hardie's recommended product, the Gyprock CSR Wet Area Base Coat is a comparable product that can also be used in this application.

This gap should be manageable as it's unlikely you will have too much water hitting the ceiling. As long as the top plate runs the full lengths as backing, you can use the beforementioned wet area base coat to back fill this gap. Once covered with cornice, you will not be able to see it anyway.

If you need any further advice, please reach out.

Jacob