tile over anhydrite screeds

[toshtiles11771]

Hi

Looking for a bit of advice, I have been ask to tile a kitchen and shower room floor in a new build by a contractor. Just found out today it has a anhydrite screed on the down stair floor.

I have looked on the net for information and it said that it has to be mechanically [FONT=arial, helvetica, sans-serif]abraded and an appropriate primer to be used.

Just looking for any information or advice from anyone who has tiled app on this type of screed.

Thanks
Tosh Tiling [/FONT]

 

[Gazzer]

http://www.tilersforums.com/tile-ad...00-method-prep-priming-anhydrite-screeds.html

 

[Gazzer]

On a more personal level. When faced with these screeds I Sand the floor with a 7" rotary sander with 40grit discs. I hoover the remaining dust away and I have used N&C Gypfix adhesive.

 

[toshtiles11771]

what type of primer did you use ? Flexi cement base adhesive ? slow or rapid set ?
It's just I've read a few posts of the tiles failing, its a big area and don't fancy having to fork out for any rework.

 

[Gazzer]

There is no need to prime with Gypfix according to the manufacturers as it is a gypsum based adhesive.

 

[White Room]

I thought those screeds were not to be used in shower rooms.....

 

[Gazzer]

I thought those screeds were not to be used in shower rooms.....

I assumed when he said Downstairs floor he meant just the kitchen floor.

 

[Spud]

I thought those screeds were not to be used in shower rooms.....

It is not recommended Mark but can be done if you tank it

 

[toshtiles11771]

thanks for all inputs guys ! Yes there is to be tiling in a shower room (not wet Room), is it still recommended to tank floor even if there is a shower tray ?

 

[White Room]

From reading Garys post, the floor where it's going to tiled in the shower room will need tanking....

 

[Ajax123]

Tanking in the shower. Ideally a joint in the screed between the shower and the non shower but if its not there tank beyond the bit that will get most of the water. no tanking required elsewhere.

1. Abrade the floor as already described ( I usually go for 60 grit but 40 is fine)
2. Make sure the underfloor heating is comissioned and run ( properly!!)
3. vacuum any remaining dust
4. Test it to make sure it's dry enough
5. Tile it.

If tanking is used you are fine to use a flexi cement adhesive ( I would Recomend thisin the wet areas anyway)

Everywhere else you do ot necessarily need a primer

Here is a listof adhesives which can be used primerless

CSA from granfix
tile to Gypsum from norcross
gypfix from n&c nicobond
h 40 Eco ideal from kerakoll
benfergyps from benfer

There are probably a few others that I don't know