tiling to 2 year old gyvlon screed

[merit]

hi all got a job im pricing at the minute,gyvlon screed been down for 2 years what sort of prep do i need,
would i still need to scrub it ?
thanks

 

[DHTiling]

Yes you will need to sand it to remove surface contaminants..

Have you tiled to anhydrite before..?

 

[Ajax123]

As with ALL gypsum, calcium sulphate, anhydrite and hemi hydrate screeds Sand it, vaccuum it, make sure it's dry, checks it is sound and free from soft spots or contamination, then tile it using a suitable compatible adhesive. I would go for something like gypfix from nicobond or GBTA from creative impressions.if it is at all possible you should avoid using cement to til direct to gypsum screeds.

 

[merit]

spoke to bal and weber and there advice is to just prime it and tile, bal reccommend ptb because there is under floor heating in the screed, weber say two part,
ive tiled on these screeds before after removing top and cleaning,but they were new screeds tech guys say it should have no probs because its been down two years, theres about 70mts in total
so it needs to be right

 

[Ajax123]

The fact it has been down two years has nowt to do with anything.

If you want to use bal or weber then go for it but bear in mind that they do cement based systems and if it is not done perfectly you may face a failure due to chemical incompatibility or primer issues. One of the mst common failures that is Coe across is where the primer fails to penetrate into the screed surface. This can occur for a number of reasons. Make certain that you dilute the primer according to manufacturers advice. The bal needs diluting 1:1 forthe first coat and neat for the second coat. Make sure it soaks in properly and dot put too much on.....more is less so to speak.

I personally would not use cement as I have too many failures to talk about. I would instead use a primerless system which is chemically compatible. There are plenty available these days. Nicobond, forbo, creative impressions, kerakoll, benfer, norcross, granfix to name a few. Up to you though.

Also if it has underfloor heating I would recomend that you get this recomissioned unless it has been run regularly. Has anyone even living inte property with the screed uncovered?

 

[TT Tiling]

good advice there ,get the heating on ,make sure its dry , i use a two part sealer ,screed master good one then use your 1 part flex add away you go

 

[Gazzer]

As always I would follow Alan's advice, adhesive companies will tell you their way and sell their brand. Alan has no axe to grind there.

 

[Robb o]

Sound advice
Defo agree about not compatable with cement.
Make sure that all the Latence is removed, have seen alot of vinly and carpet fail on-site because it was'nt sanded properly,let alone tiling.

 

[merit]

thanks for the in depth response , id take that advice over the tech people, there experience is limited, bal did recommend the diluted first coat ect , id rather price for
compatable adhesives to take the risk factor out of the equation, so id scrub, vacum,no primer then a suitable adhesive.the house as been on getting built for a while hense the two years, so i suppose the heating has been commissioned ,ill find out more when i go n av a look
thanks again

 

[Ajax123]

If the house has been lived in I would strongly recomendation moisture test. Bear in mind it has had two years to get damp as well as to dry out. It might also have greasy spots from cooking and spills. That said the most important bit is still sanding and vacuuming. Where no primers are used dustwill be your enemy. NOT scrubbing.......you are not cleaning a door step . So basically vac not sweep, sand not scrub......

Two pack primers are good for combatting the chemical reaction but do suffer the same issues of penetration into the screed sometimes. They are a good choice if you use cemet but still nt as good as eliminating the risk by using compatible systems.

 

[The D]

This stuff should come with a warning label NOT SUITABLE FOR CEMENT BASED ADHESIVES. I hate this stuff with a passion

 

[Ajax123]

This stuff should come with a warning label NOT SUITABLE FOR CEMENT BASED ADHESIVES. I hate this stuff with a passion

Watch this space deano.....

 

[Ajax123]

To be fair though deano being two years old and lived in I would make exactly the same recomendations for any screed or concrete with the one exception I would Recomend priming.....

 

[The D]

Watch this space deano.....

I will :smilewinkgrin:

 

[bugs183]

It appears that bal are making no attempt to keep up with adhesives for these screeds. Just prime and use PTB is just the wrong answer. I spoke to Norcross about their 'tile to gypsum' product, technical said it was fine for an anhydrite screeds, i asked if i could fix Ditra with it to said screed and they said no, use a cement based adhesive. When i quizzed them about the incompatibility it all went quiet. I still can't believe the mixed answers you get over these screeds!

 

[Ajax123]

Norcross have only just got on board. You would, I am sure, be fine to stick ditra down with their addy but as it is gypsum you probably woud not need it.

Remember that you can stick to these adhesives with cement. The issue is compatibility which forcesarequirement fr a primer. It is here that starts to trip up. The adhesive does not stick to the screed it sticks to the primer. If the primer to screed bond is weak for any reason the bond will fail taking the tiles with it. If the primer is not applied thick enough you can get chemical reactions which cause delamination.

To be fair BAL do have a system that works provided their rules are followed to the letter. So do many other manufacturers.
Problem is that the rules don't fit with the industry requirements and practices. There is a fundamental issues in that the majority of cement/primer systems are not robust and will not tolerate abuse, even of the smallest kind.

Now I know that all tilers are perfect tradesmen and do everything by the book and properly........ But do they really. This is not a dig at the tiling trade. It is a simple statement of fact. Things happen on site which cause us all to take risks...... Yes I know I am going to get the "I always do it right" brigade going now.......

If we all did everything perfectly then there would not be failures. If we do everything by the book and there are still issues then the book use be wrong.

Simple fact is that whilst thy are more expensive at present gypsum adhesives are far more robust on gypsum bust rates than their cement/primer counterparts. They remove several risks altogether.

I await the righteous onslaught .....

 

[bugs183]

I think it would be unfair for you to get moaned here just for stating the facts, most of which it appears you are the only one who actually understands and can explian with any authority.
Yep is a pain that these screeds have kinda just turned up and the tiler has to deal with them. I for one don't skimp ony part of job as i'm lucky to get jobs where i'm screwed down on price. If i can't do it right i don't do it at all.
Trouble is if you took the time to phone all the tech departments, everyone is saying something different and each manufacturer contradicts the other, so we end up being totally non confident in a job that we've known for years.
So to end Ajax, if primer is such a big deal which it now appears to be, would we tilers be best priming with an epoxy primer for these screeds??????

 

[bugs183]

Insert words in above post where needed, posted on my iphone....

 

[merit]

when you recommend sanding to what extreme, how much of the layer should i be taking off , and type of machine to use ,also would the screed have taken in atmotspheric moisture?
cheers

 

[The D]

That is because you and me are the guineapigs and they have not finished testing on us yet

 

[bugs183]

Bit ironic that Dean, as my last name is Bunney!

 

[Ajax123]

when you recommend sanding to what extreme, how much of the layer should i be taking off , and type of machine to use ,also would the screed have taken in atmotspheric moisture?
cheers

In order

Any non screed contaminants or friable loose material. You are not aiming to take off any screed.

Rotary floor scarifier with 60 grit paper or alternatively enclosed shot blasting unit ( for large areas.

Unlikey. I will of coursesoakmup spillages just like sand ement but is not generally troubled by atmospheric humidity unless it is excessively high then as with all screeds it will reabsorb. It will quickly retry once the atmosphere reduces though.

 

[Ajax123]

That is because you and me are the guineapigs and they have not finished testing on us yet

Gonna be providing free carrots soon ;p

 

[Ajax123]

I think it would be unfair for you to get moaned here just for stating the facts, most of which it appears you are the only one who actually understands and can explian with any authority.
Yep is a pain that these screeds have kinda just turned up and the tiler has to deal with them. I for one don't skimp ony part of job as i'm lucky to get jobs where i'm screwed down on price. If i can't do it right i don't do it at all.
Trouble is if you took the time to phone all the tech departments, everyone is saying something different and each manufacturer contradicts the other, so we end up being totally non confident in a job that we've known for years.
So to end Ajax, if primer is such a big deal which it now appears to be, would we tilers be best priming with an epoxy primer for these screeds??????

Epoxy is certainly far better than acrylic.

 

[merit]

been to see the above floor , told customer what is needed ,scarify then gypsum based adhesives ect, taken it on board, just need to find stockist of gypsum based adhesives to find price, any pointers, up in the nort east of england
thanks