Hardboard or floorboards?

[wazaps]

Hi, a tiler told me that if I put down two layers of hardboard instead of one on the joists, my bathroom floor tiles would not crack. Is it better to put down floor boards? If I do either of these two remedies it seems to me that I would be left with a trip hazard between the bathroom and passageway. Is there any other possibility?

 

[eddcottee]

I wouldn't use hardboard at all. Without having seen it, I would suggest 18mm ply onto the joists and then 6mm cement board on top of that. If you type "James Hardiebacker Installation Guide" into google, you'll see what it is and how to install it. Any tiler should really know that, so I'd be asking questions about your proposed installer and perhaps be getting another opinion

 

[wazaps]

Thanks for the information about 'Hardiebacker,'much appreciated.