lafarge low laitance screed,tiling with 600x600 polished porcelain

[deankyall]

job of 135m2 on low laitance screed,am i correct in saying ,does not need scarifying,just hoover, prime with suitable acrylic primer 1-1,second coat neat,mapei rep said today use primer g,then keraquick,check moisture content,when correct ,just tile 40m2 max bays,client didnt want any expansions!!!,i wont do without,so he wants just silicone matching colour joints.

Any other suggestions would be appreciated thanks

[Bri]

How long has the screed been down mate, and what thickness is it?


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[Sir Ramic]

You may still need to sand the floor. I wouldnt be using that method either , Gypsum adhesive for me.

[deankyall]

guys ,ive talked to reps today,one said he had been to 9 failures in the last year,3 of them were gypsum adhesive,so i dont buy into that,im sure as long as prep and drying time is done correctly,cement based should be ok,mapei havent introduced theirs into this country,as they see no need,just saying what i was told.i can see the point of maybe an epoxy primer,as this stops the reaction between the cement and the screed,
also reading more on here from the lafarge guy , also says this type dosent need scarifying??

[Sir Ramic]

I think you will find that Alan says " It may not need sanding" The last 3 Low laitance screeds I have done all needed it.

[jay]

Gyvlon floor....

[deankyall]

right,how did you determine it neded sanding,scrape the top ,if its soft then is that it?
This is an example of whats wrong with the tiling industry, you try and do the correct method ,but there seems to be different correct methods according to who you speak to,after speaking to the reps of top adhesive companys i felt confident this was the way to go,i mean if you cannot count on these people,whats the point,isnt it about time that the industry as a whole got their act together and put some solid guidlines down ,by this i mean all the adhesive companys and screed suppliers etc? then we can all tell the customer "this is what you have to do" no ifs or buts,instead they are confused by differing opinions from different people qouting for the work, its getting to the stage where people dont want to take work on because if it goes wrong your in the deep stuff,****es me off,
the customer had no clue whatsoever about the implications of tiling onto this at all,so not told,then gets a shock when i tell him ,especially cost.

[andy allen]

any underfloor heating?

[deankyall]

yes gyvlon floor,the low laitance version

[deankyall]

yes underfloor heating too

[Bri]

Ok I'll give you some direct info from Alan (Ajax123), when I did my first Gypsum screed I called him for some advice and he said the the low laitence screeds need a scarify but, not anything to severe, just key the surface, then hoover thoroughly and prime. Now this next bit of info is from personal experience, I sampled cement based adhesive and gypsum based adhesive (with appropriate primers) on the same floor and the tile fixed with cement based adhesive popped up with a scraper after 72 hours! I know all the big manufacturers claim their cement based adhesives will adhere to gypsum with the correct primer but I know for a fact that thy are NOT as successful as gypsum based adhesives. Alan has (his words) seen many failures on anhydrite screeds and not one has involved a gypsum based adhesive. Please listen to this advice, it is well informed and is from direct experience, yes cement based adhesives will work on gypsum screeds but they are, categorically, never ever going to be better than gypsum based adhesives.

[deankyall]

is there a way i could contact him,then i could maybe get the customer info from the horses mouth

[Sir Ramic]

You can PM here View Profile: Ajax123 - TilersForums.co.uk | Tile Forums | Tiling Forum

[Rich]

The advice given above is spot on. I tiled a few of these screeds over the last year or two, they are not to be taken on lightly. The prep has to be carried out correctly. The gypsum adhesive I used was really good and the advice we are quoting was from the man in the know and not from some1 wanting to sell there product. If you can get your hands on some gypsum adhesive then get it and I would still give the screed a but of a scrape up. The expansion joints are essential.

[deankyall]

yes i just thought that so did it already,cheers though

[deankyall]

yep thats what i told him about expansion,by the way what did you use to rough up the surface,?what about a floor sander?

The advice given above is spot on. I tiled a few of these screeds over the last year or two, they are not to be taken on lightly. The prep has to be carried out correctly. The gypsum adhesive I used was really good and the advice we are quoting was from the man in the know and not from some1 wanting to sell there product. If you can get your hands on some gypsum adhesive then get it and I would still give the screed a but of a scrape up. The expansion joints are essential.

[Rich]

I used a sanding pole. If the screed is still slightly soft, you can just use a stiff brush.

[Bri]

is there a way i could contact him,then i could maybe get the customer info from the horses mouth

I'll PM you his work mobile. This type of screed is his profession and, IMO, if you stray away from his advice then prepare for failure. I don't mean to sound harsh, rude or come across as a 'know it all' but, I am speaking from experience.

[jay]

Has the floor heating been commisioned

[Sir Ramic]

I used a 7" variable speed angle grinder with 60 grit disc.....messy job though but when you see what comes off the floor you will understand screed.jpg

[deankyall]

yes been on low heat for about a week,so a while to go yet

Has the floor heating been commisioned

[deankyall]

i think ill go for gypfix,or i will tell customer to go with it,at least no priming then,ill contact nicobond monday,wonder if theyll do a deal for large amount,anyone know of m2 for a bag based on say 10mm trowel ? plus buttering back

[deankyall]

unbelievably,i just got back from another job,called in last night as an emergency,aga being fitted tuesday,got there and it was liquid screed,so had to tell them the process,they called builder who knew nothing about it at all,he called easyscreed ,who said it just needs 2 coats acrylic primer then its ready for tiling,there is another 60m2 of travertine to do,i scraped of the bit where i had to tile this morning then primed,showed her what it involves,so more gypfix needed!!!

[Ajax123]

You can contact me at work dean. My mobile number is 07545 932723

To all the other forum members i am happy for this mobile number to be in the public forms. I wold rather recieve calls for advice before the ob is done than receive calls about problems afterwards....

I dont usually answer agter working ours but you can leave a message

[deankyall]

many thanks,i will call tomorrow,def want to cover all bases here and make sure the customer recieves correct info,i also popped into the local biggest tile wholesalers this afternoon and not one salesperson or employee knows anything about tiling onto this,and they are selling stuff to the public and trade,apparantly they have a kerakoll trade evening upcoming so i will be asking questions there,as i have read the post about problems with their adhesive,although i have used their tenoflex on walls and found it resonably priced and good to use.

You can contact me at work dean. My mobile number is 07545 932723

To all the other forum members i am happy for this mobile number to be in the public forms. I wold rather recieve calls for advice before the ob is done than receive calls about problems afterwards....

I dont usually answer agter working ours but you can leave a message

[deankyall]

guys is this any good for measuring the moisture content from the screed?


or this

[Ajax123]

Bottom one is but not top one

[deankyall]

update,customer has decided after i opened a nicobond acc,to go with kerrakoll h40 ideal,have spokn with rep ,who has agreed to do a carbide bomb test,told me i need no primer,and thats it meeting with him next week,anybody used this with fugabella grout and matching silicone?

[Sir Ramic]

I had a meeting with a Kerakoll rep and he said priming was needed.

[deankyall]

who do you believe??,aparently if you prime it puts moisture back into the screed which is then trapped there ,most failures are because there is moisture in the screed he told me,after sanding,the adhesive bonds with the screed,it says on bag no priming needed!! have you used it ,if so which method did you use?the rep is coming to site and only when he gives go ahead will i start,customer( a builder) is doing the prep.this is a worry ,if it goes wrong i wonder where we would stand given his input?