tiling to 2 year old gyvlon screed

[merit]

ive spoken to all the tech departments from adhesive cmpanys now ,they all say the same , sand vacum prime cement based adhesive,and it will be fine ,problem is if it goes belly up,what back up would these companys give you, in my experience none at all,so i need some gypsum based adhesive, where do i source this product
thanks

 

[Ajax123]

See post 26

 

[RJK]

Hi All, new member with the same problem, requesting advice on how to create a successful barrier. Summary:- 1) New house build in 2009. 2) The house is installed with a Gyvlon screed on downstairs and first floor. 3) I have suffered delamination on all floors where tiles have been fitted. 4) I have now lifted one bathroom floor and all the tiles had lost their bond to the floor apart from one tile that was fixed to the point where the drain went through the floor, this area was back filled with a normal cement based mortar. 5) When the tiles were lifted the floor was covered in a crystals which I now realise were Etringate crystals and the calcium sulphate floor was covered in small corrosion pits, each containing substantial crystal growth. I now have a relatively good understanding of the problem and as a client of a new build property am quite (no very) surprised that the building community, i.e. floor supplier, adhesive supplier, builder and tiling subcontractor can let such a problem arise, particularly when so much is written about the issue! Also discussing the issue with my building contractor, the tiling supplier and also the flooring supplier, none of them realised this problem exists. I have two questions, I am looking for advice about what product I can use to create a clear barrier in the bathroom that I am currently replacing and the second question is I have a very large tiled area in the downstairs kitchen that has suffered total delamination and I need a repair method that will enable me to lift individual loose tiles and treat the underlying area before re-bedding the tile. I recognise that the answer to both of the above two questions may be the same as long as the barrier thickness is small enough not to lift the tile in the second example. I also have another complication, that I only have 4 spare tiles and they are no longer available so I need a successful & easy method of removing the cement from tiles? So any help would be appreciated!

 

[DHTiling]

Hi, The bathroom floor should also be tanked with them being classed as a wet area.. IMO the floors will need to be sanded to remove the sulphate issue.. are you claiming for this work from your installers.?

 

[Ajax123]

I now have a relatively good understanding of the problem and as a client of a new build property am quite (no very) surprised that the building community, i.e. floor supplier, adhesive supplier, builder and tiling subcontractor can let such a problem arise, particularly when so much is written about the issue!

It's probably cos they're all to busy blaming the screed...

 

[Stef]

It's probably cos they're all to busy blaming the screed...

Alan, quick question.
In all the failures you have seen on these screeds, is it always the fixers lack of understanding about the screed (without proper prep) that the instillation has failed?

 

[Ajax123]

Alan, quick question.
In all the failures you have seen on these screeds, is it always the fixers lack of understanding about the screed (without proper prep) that the instillation has failed?

It's not as easy a question to answer yes or no to. I have come across many instances where the fixer believes he has done everything by the book based on a book written for example by the adhesive manufacturer. I often get told "I used the correct materials, primers and adhesives etc". When in actual fact despite assurances from adhesive manufacturers they are inherently flawed. Most of the failures I have come across are due to 1 or a combination of 2 issues.

1. Excessive moisture in the screed
There are many reasons why this cold happen
2. Inappropriate use of primers leading to the primer-screed bond failing
It could be that the primer needed to be diluted but the manufacturers instructions did not say so. It could be that the screed surface was too dense because it was in sufficiently sanded (this is one of the potential issues with the low Laitance screeds that are available in the market where people say "they don't need sanding") or it could be something else.

the latter reason is one of the reasons I have tried to promote primer less systems where possible because it removes a risk.

When assessing such issues I always try not to apportion blame or responsibility but sim outline what has gone wrong. This is sometimes diffiucult because everyone wants to blame someone and its often no one persons fault...

Ettringite is actually quite a rare thing to see these days in terms of reasons for failure.

 

[Stef]

Quick update on the Gyvlon Screed.
Done the moisture test,

This is looking good for tiling.

Laid a test tile to see what would happen,

The tile wasn't back skimmed, laid straight onto an 8mm bed of weber spf rapid, 2 coats primer.

 

[Stef]

This was lifted after 24hrs & still held quite a bit of moisture below the tile, you can clearly see the difference.

 

[Stef]

The builder wants to wait before tiling, mid October getting spoken about.

I'm still not sure if all the laitance has been removed from the top if the screed,
Sanded with a belt driven floor sander but still getting a bit of dust when I go over it with a hand sander..