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

 

[paul flight]

doug is right . get hold of the builder tell him what you want done at no cost to you . if he is any good he will do this work . tell him you want a experienced tiler to do the work. you have paid a lot for this to be right.! be strong and dont take no for a answer .. in fact put it in writing to him so that he knows that you have done your home work on this on .. which he did not.

 

[Sukie666]

Mikethetile - don't think we can go for the 25mm unless we take the kitchen apart. What is the purpose of the noggins and do they sit on the joist?
thanks

 

[mikethetile]

they sit between the joists and prevent sideways movement

you cut 6x2 to fit tightly between the joists and fix them in a row, you then wedge at either end between wall and joist,this takes all the spring out of the floor

the kitchen will need to be removed to do this work

theres no point in tiling over boards that have been sealed with pva as the water in the adhesive reactivates the pva preventing the adhesive from bonding to the substrate, one option if there is no deflection in the floor is to stick and mechanicly fix backer board to the ply and tile on that, this will raise the floor by about 6mm

the issue with that is if theres any deflection in the floor. try bouncing in the middle of the floor on the balls of your feet and see if you can feel any bounce or give

 

[grumpygrouter]

Just as an aside to previous advice, if you go down the route of using BAL adhesives on to the ply then BAL DO NOT recommend priming the tiling face of the ply and if you do it would invalidate their warranty (which isn't up to much for domestics anyway!)

 

[DHTiling]

Hi..

Sorry you have such a bad installation..

You would be wise to get an independent assessment of the job in hand.

The builders have not followed uk standards BS 5385 and the fixing method is totally wrong..

You are not in the wrong here and should not be paying for extra tiles or materials .

IMO all the tiles will eventually fail due the method and prep used... you did the right thing coming to a tiling forum rather than ebuild as we specialise in this sort of advice.

PVA is not a recognised primer for tiling and really on that spec of timber floor an S2 highly flexible adhesive should have been used.

Please contact the builder ASAP and stress your concerns highly... but an independent report will back your concerns up..

 

[The Legend; Phil Hobson RIP]

Hi Sukie, As Dave says above. Why should you incur any extra costs, this job does not conform to BS 5385. The builder should rectify bad code of practice faults ie. PVA dot and dab etc. I would pursue him through the courts if I were you. If he had adhered to the correct methods, you would not be in this position. Good luck, and let us know how you get on

 

[Sukie666]

So I can't reuse the current ply? No one has mentioned that before. That would complicates things enormously. There is a fair amount of flex in the floor. You see it bounce a bit if you are heavy footed when walking. Obviously it would be difficult to replace the ply without removing the kitchen. But with the kitchen stretching 7 meters long (L shape) with a composite worksurface and glass splashback throughout + a large island - impossible.

Does anyone else agree with this? Can I negate the effect of the PVA somehow?

Though not guaranteed, I was encouraged to hear Doug's thought on my option 2 with the ditra mat for extra support. Now I am very concerned again. As it stands, would anyone recommend lifting the tiles and replace it with an engineered wooden floor?

Dave & Phil, I know I shouldn't have to pay for any of this, but trying to get the builder back to do anything has been close to impossible. I have considered going down the legal route but having spoken to a number of friends and other people who has had problems with builders - the consensus is it's not worth the bother. No one i have spoken to has ever got anything money back from the courts.

What to do, what to do........my dream kitchen is now a nightmare.

 

[mikethetile]

if you can feel the deflection then any tiling job is going to fail, your builders should have gone through this with you at the time and resolve it before tiling

its a difficult one this, engineered wood is not the best in a kitchen as water ingress will damage it over time, tiles are the best option but will require a lot of prep now to put right.another option is Karndean

you chose and paid for a tiled floor and really you should get what you paid your builder for. problem is if you let your builder away with this you lose out and yet another builder gets away with it

we can help you through this

 

[doug boardley]

So I can't reuse the current ply? No one has mentioned that before. That would complicates things enormously. There is a fair amount of flex in the floor. You see it bounce a bit if you are heavy footed when walking. Obviously it would be difficult to replace the ply without removing the kitchen. But with the kitchen stretching 7 meters long (L shape) with a composite worksurface and glass splashback throughout + a large island - impossible.

Does anyone else agree with this? Can I negate the effect of the PVA somehow?

Though not guaranteed, I was encouraged to hear Doug's thought on my option 2 with the ditra mat for extra support. Now I am very concerned again. As it stands, would anyone recommend lifting the tiles and replace it with an engineered wooden floor?

Dave & Phil, I know I shouldn't have to pay for any of this, but trying to get the builder back to do anything has been close to impossible. I have considered going down the legal route but having spoken to a number of friends and other people who has had problems with builders - the consensus is it's not worth the bother. No one i have spoken to has ever got anything money back from the courts.

What to do, what to do........my dream kitchen is now a nightmare.

Sukie I said that ditra would help negate lateral deflection that is the sideways movements. Ditra will not add extra support for vertical deflection ie "bounce" and that if vertical deflection was present, even with ditra it would still lead to tiles debonding.

 

[Sukie666]

Doug, that was understood but thanks for the clarification. Just that, having some hope was just better than none.

I know this is a tiling forum and I guess most would suggest retiling properly. But if I don't want to take the kitchen up completely, is replacing the tiles with a wooden floor my best bet? Anyone please?

thanks
Sukie.