Uneven hardiebacker on victorian terrace bathroom floor - Tile Advice

[Ross tile]

Hi there - so i have ripped up the old tiles and old layer of ply and cork. Replaced with 12mm hardiebacker screwed in along with a layer of adhesive between the backer and the floor. There is some discrepancy of maybe 5mm between aome of the boards. Do i need to start again? Im using flexible adhesive and the room is around 1-2m2.

Current plan has been to rip up the problem boards and reapply

Any advice would be great!

 

[Ross tile]

I.e. What sort of tolerance is okay and can be dealt with by using more adhesive on the tiles

 

[J Sid]

if the floor is solid, put a bag of SLC over the whole floor

 

[Ross tile]

Its old wooden floorboards with a number of small gaps unfortunatrly.

 

[Spare Tool]

Its old wooden floorboards with a number of small gaps unfortunatrly.

Prime and level after you've fitted the hardi and taped the joints

 

[Ross tile]

What would be an example product / primer?

Is it normal for the hardi not to be exact and to use a primer?

Thanks

 

[Spare Tool]

Personally I prefer Tilemaster levelflex and would use there primer, but most reputable manufacturers make a leveler suitable. Your boards will only be as flat as the floor your screwing them to..

 

[Time's Ran Out]

I’ve found that the 12mm Hardi can be of varying thickness.

 

[J Sid]

if you have any gaps round the edge fill with expanding foam, also use to create a dam across the door.

 

[Waluigi]

Be careful with HB. Often it can be poorly stored and as it’s such a rigid material, if the base of the storage pallet (or whatever) isn’t flat then every last board will be on the wobble. I hate the stuff, especially the 12mm

 

[Ross tile]

Thanks for all the replies - i've attached a photo for a bit of context. So currently my plan is to put down the rest of the HB as most of it has already set and is flat, seal the joints using cement board tape and adhesive, seal up the area with battons / expanding foam around the skirting board / door / pipe holes in floor, apply self levelling compound, hope for good results and hopefully get tiling this weekend.

This is beginning to feel like it will be a very messy job but hopefully its reasonably straightforward. Feels like a lot fo effort for such a small area but may as well do it right