Tiling on a suspended floor

[Sukie666]

Hi, I desperately need some advice. Six months ago we did up our kitchen diner. With a modern kitchen and two young children we decided to go for large format porcelain tiles and a wet underfloor heating system. Two months ago, a number of the tiles started to lift. Having been on the ebuild forum I understand it was due to the poor prep work on the subfloor. For an area of 36sqm, using 60x60cm porcelain tiles with UFH my builders should have added struts before putting the 18mm ply wood. The ply was screwed down every 9 inches instead of 6. They used a pva primer and to top it, used a dot and dab method with the flexible adhesive.
I managed to get the builders back in after endless calls. They took up one row of tiles which came up with ease. I made them screw the ply down every 4-5inches and used the recommended BAL primer and single part flexi adhesive. These seem to be okay at the moment but how long before they go again? The rest of the kitchen is all coming apart now and will need to be dealt with.
Question is, do I cut my loses and just go for wood or try to stablise the floor and retile? *I've been told that the only way to guarantee against failure is to strengthen the floor with struts. However, having spent nearly £4k on the Ufh I am reluctant to throw all that away and spend another 4-5k on it's replacement *after the supports have been added. Plus, with the new kitchen, it would be extremely difficult to get to pipes etc.
Is there another way? Would screwing down the ply more and using the BAL products be enough? Can Ditra matting or movement joints be use to help?
Any help/advice would be most appreciated.
Thanks

 

[mikethetile]

the chances are that the floor failed due incorrect fixing ie dot and dab

and sealing the timber with pva, if the 18mm overboard has taken the deflection out of the floor then that shouldnt be a problem

as to how long they wwill last depends on haw well they were fixed

 

[enduro]

Sounds like bad fixing of the tiles...PVA that's a No straight away, and with tiles that big he should of applied adhesive to floor and back of the tile for maximum coverage. And did he use adhesive designed for porcelain tiles do you know?

 

[diamondtiling]

Whats the makeup of this floor Sukie?

 

[Sukie666]

Hi, the house is Edwardian with the floors suspended on concrete/brick pillars and wooden joist of 150mm width. The gap between joist is 300-350mm.
We had the wet UFH put in between the joists with the insulation then the 18mm plywood. The ply spanned two/three joists and screwed down every 8-9 inches. Then on top the PVA primer and the adhesive and grout. As the floor was not level, a huge amount of adhesive (Tilemasters rapidset flexible) was use, in some places with a thickness of 13mm.

Having spoken to a number of tilers on the phone and forum, I am aware all of the above is wrong. I just don't know what I can do to fix it without starting from scratch (ie removal of the kitchen units and island - all very heavy with composite worktop, the removal of the UFH etc). The kitchen units will surely be damaged and my guarantee invalided. The heating engineer said he is not sure he can get to the pipe work without removing the kitchen units and suggest we put some radiators in instead.

I see the options as:[FONT=Verdana,Arial,Helvetica]
1. lift tiles, ply & UFH and add strut and redo entire job (properly).

2. lift tiles, screw down ply every 150-200mm, use BAL primer & adhesive and pray.

3. get rid of tiles and put wooden floor down instead

Option 1 very expensive and probably not practical.

Option 3 - also expensive and will not give the desired look or feel but wood is probably more forgiving? I don't know the prep requirement for that yet.

I'm leaning towards option 2, but without the struts, what are the chances that the tiles will lift again within a year or two?

So, would adding Ditra matting or movement/expansion joints help? [/FONT]Someone mention adding noggins as well. Can any of these be fitted rectrospectively? I'm getting conflicting advice and would love to hear from anyone who has had a similar experience and how to resolve it.

thanks

 

[Deleted member 9966]

Hi Sukie

Sorry to hear about the predicament you're facing. I would suggest that you need to get the builders to repair the mess they made. Bearing in mind all the work was carried out six months ago, their workmanship should still be under guarantee.

Their fixing methods are wrong, and the products they used are wrong for the tiles. They are obliged to rectify their work if it has failed so badly.

Can you let us know where in the UK you are located? Maybe one of our Trusted Advisors could pop round and give an opinion?

GRR

 

[jay]

to go with the advice above recomend you get a pro tiler in and do the job right

 

[Sukie666]

The work is under guarantee but I am having to pay for the extra tiles, primer and adhesive. They have agreed to come back next month to try to fix the problem. They are only lifting the visible tiles and not the one under the units. They said they don't need to move the island, just raise the leg of the the units to get the tiles up. Not sure how they intend to put the tile back. They are definately not taking up the UFH and adding the additional supports.
So do you guys think that screwing the ply down bit more and using the BAL products should do the job? I really don't want to do all this again and throw away more money.

Other thread on this forum suggested using Ditra matting - can anyone comment on that please?

I'm in the SW London area, near Richmond.

thanks.

 

[doug boardley]

the ditra matting will not make the substrate deflection free Sukie (and deflection does appear,imo, to be an issue here.) The ditra will only negate lateral deflection caused by expansion/contraction of the substrate due to your UFH. The fixing prep and methods appear to be all wrong. Also I think I would have used 25mm wbp ply to make the floor more solid. I can't really see an easy fix in this situation.

 

[Sukie666]

Oh, not worth putting the ditra mat down then? Given the situation - what/how would you suggest I tell the builders to do to fix this.

thanks

 

[doug boardley]

you misunderstand me Sukie, ditra is worth putting down, but in your situation I feel the installation would have failed anyway due to what appears to be vertical deflection and poor fixing practice.

 

[mikethetile]

joists laid @ 12" centres on brick sleepers wont usually deflect and even with only 6x2 for joists the close spacing makes up for it, my downstairs floors are exactly the same consruction and dont deflect at all

if your having the builders back to rectify then dougs advice on using 25mm wbp would be wise as they used pva to seal the boards which is incorrect and the 18mm are now useless

while they have the boards up they could add noggins to brace the floor, they should be able to do this without disturbing the ufh

talk to your builders and see what you can do with them, if no joy stay on here for support

with the issue of replacing the tiles, all tiles ned to come up and be replaced as they are incorrectly fixed, I realise this entails removing the kitchen but they will have to bite the bullet and put it right and get real tilers in next time

 

[Sukie666]

I see Doug, so if they screw it down properly, use the ditra mat and correct adhesive and primer (BAL?) and apply it properly that should give a better fighting chance?

thanks

 

[doug boardley]

it should do Sukie, altho' Bal is very good it is also very expensive compared to comparable quality adhesives such as Mapei Keraquick used with Primer G.

 

[Sukie666]

Twice the price of the Tilemasters adhesive in fact! But, a number of the ebuild forum members recommended it along with the Tiling Association. I would much rather pay more than have to do this again.

With the ditra matting, is there anything particular I should be aware of or any 'No no!' to keep in mind?

thanks