Tiling on an uneven floor

ripkord · Oct 11, 2009

lifted a couple of tiles to see what im up agaist - looks like mdf or something under there - has been warped through dampness getting through cracks in the tiles... will putting hardi backer down on top of this be ok?

thanks

tfs · Oct 11, 2009

No mate!

You will need to lift the floor to eliminate any risk of this happening to the rest of the floor. At the end of the day its your choice but I would lift and fix nex tiles over a suitable sub floor

ripkord · Oct 11, 2009

Unfortunately I cant lift the existing floor without ripping out the bath too - this is a job to make the flat market ready and not really a long term solution, having said that I want to do a good job!!

tfs · Oct 11, 2009

I imagine some people would just replace any damaged tiles if they were planning to sell the property!

ripkord · Oct 11, 2009

haha, I'm not that shoddy

Daz · Oct 11, 2009

The correct advice would be to rip the existing floor up and replace with either 18mm or 22mm ply. In your situation, can you not just replace the damaged floorboards and then re-tile?

ripkord · Oct 12, 2009

not really, the entire bathroom floor is 2 large pieces of MDF / something like that - the seam between the two parts is where all the broken tiles are so there must be some kinds of depression at the seam. The way the bathroom is tiled and the way the bath is tiled in - if I was replacing the floor I'd be giving myself far more work than I had set out to do!

Would it be worthwhile putting down a thin strip of ply over the seam before putting the hardibacker down?

ripkord · Oct 12, 2009

I have attached a quick mock up in mspaint to try and demonstrate what I'm talking about. The large terracotta coloured bits are the floor. the squares are the tiles, obviously

(not to scale

) the large rectangle on the left is the bath.

The tiles are crached right along the seam between the two boards, cant see if theres any real dip or recession. Would an uncovered seam cause cracks?

Thanks.

jay · Oct 12, 2009

hi as advised above rip it out back to joists and start again water has got into mdf and swelled it its completly stuffed now if you try youl be wasting your money:8:

Deleted member 9966 · Oct 12, 2009

hi ripkord

thanks for the drawing there. that certainly helps to explain the situation more.

if the join between 2 boards is where you say, and there is no additional overboarding on the floor before the tiles were laid, I think it's pretty conclusive that the tiles, adhesive and grout failed because there was too much flex/movement in the boards under the tiles.

You need to take all the tiles up and start again in my opinion. a 6mm hardibacker board that covers both floor boards and straddles the seam would be more helpful to you. securing the hardibacker at 300mm centres or less will give the floor more rigidity and will stop the tiles cracking under the movement.

I don't see how the ply will give you any further rigidity.. The hardibacker will give the right amount of rigidity to the floor without adding an additional layer to it.

If the original floor boards are warped though, I would suggest you sort them out first if the warping causes a bump in the floor. Perhaps it might need additional screws to the joists?

I've just gutted my bathroom and have chipboard sheets down as my floorboards, and now that the original flooring (lino and laminate) has been removed and air has been allowed the flow, the damp areas of chipboard have now dried out.

best of luck and let us know how you get on. a good saying I came across on here is "Do it right, do it once"

GRR

ripkord · Oct 12, 2009

Thanks, there doesnt seem to be a recession at the seam to be honest, but there must be given that all the tiles right along the seam are broken. I had mentioned the boards look warped - they dont really, was just the angle I was at - the floor looks level from what I can see - need to get myself a spirit level and make sure. The floor looks in good shape apart from the seam - where there is a 5mm gap between the sheets!! :

Deleted member 9966 · Oct 12, 2009

ripkord said:
Thanks, there doesnt seem to be a recession at the seam to be honest, but there must be given that all the tiles right along the seam are broken.

looking at your diagram ripkord, there probably wouldn't need to be any kind of dip in the boards as such. if that's where people step out of the bath, a person just has to step in and out of there a few times for there to be enough pressure along the seam to cause failure.

the floor boards that are down either need replacing (if beyond repair) or re-inforcing. boards do bend when they're stood on, they will not be completely solid.

where abouts are you located ripkord? Maybe one of the guys from here could come round and help you to figure out a plan of action?

ripkord · Oct 12, 2009

I'm in Glasgow. I cant really justify taking out and replacing the floor - that would be a proverbial can of worms! If it was for the absolutel long term - I would definitely consider doing that!

Deleted member 9966 · Oct 12, 2009

brian c is one of our Trusted advisors on here, and he is in Glasgow too

you can send him a private message http://www.tilersforums.com/private.php?do=newpm&u=1494

ripkord · Oct 13, 2009

do I need to use adhesive to stick the hardibacker as well as screwing it down?

thanks

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