about to start a porcelain floor with tiles 1000x 1000 x 15mm.
wandering what adhesive to use.
the first sample of tile I saw had a reverse bow in it.
You could fit a 4mm packer under under each side of the level at either end of tile.
this in itself would not be a problem if all edges of tiles are flat with even hump in middle.
but then got a second sample that was dead flat.
area is quite big 250.00 sq mts domestic job and concerned about tiles have different flatness. size and flatness permitting i would fix with a 2mm joint .
would normally use stonefix rapid adhesive but architect has specified x78s.
anyone had experience of this adhesive on a very large format tile.
I want to end up with solid bed and a half pourable product seems ideal.
I would never use the old pourable adhesives laying stone as they sink and dont allow perfect flush joints.
maybe ardex products are fine.

What substrate?

250m2 in a domestic is a cracking job m8.

Keraflex maxi would be ideal...with that format of tile.....http://www.mapei.it/Referenze/Multim...%20Maxi_uk.PDF




Cement based adhesive for thicknesses from 3 to 15 mm, with good deformability, good adhesion strength and no vertical slip for ceramic tiles and stone materials.
Applications:
Interior and exterior bonding of ceramic tile and natural stone floors and walls (as long as they are not absorbent) on conventional substrates such as:
• Cement screeds and underfloor heating installations.
• Cement renders or lime and cement mortar.
• Gypsum boards.
• Brick walls and blocks.
• Concrete with more than
4 months curing time.
Keraflex Maxi is suitable for bonding small and large sizes on uneven substrates without having to smooth the flooring beforehand and for the installation of tiles (even heavy) with no vertical slip.
Also suitable where tiles have to be laid onto existing tiles on floors and walls and for bonding insulation materials such as expanded polystyrene, expanded polyurethane,

BAL PTB is good for large tiles and gts a 100% covrage

Originally Posted by mags

BAL PTB is good for large tiles and gts a 100% covrage

Expensive though isn't it...

I use PCI PTB never had a problem with large format 78S sounds like Nanolite Rapid which I found is a problem with floors to much body slow set Nanolite is better :Pete

Regarding bowing I found on a job the tile was bowed one way and flat the other, It meant you needed to make sure the tiles were laid facing the same direction(some tiles have an arrow on the back). Just a thought
1m x 1m, Rather you than me

Originally Posted by Dave

Expensive though isn't it...

£24 for a 20kg bag

Originally Posted by mags

£24 for a 20kg bag

Dave was right then mags

substrate is the dreaded anhydrite.
but has been down 4 months and underfloor heating now being brought up to temperature and down over 9 days.
House is water tight no wet trades to pull more moisture in, so cant ask for any more than that.
will prime with p51 or similar.
There will be dilex bwb 15mm movement joints in tiles through all doorways and have suggested cuttting a 30mm deep joint in to anhyrdite screed directly under these tile movement joints to force a weak spot.
Have recommended ditra as well but contractor does nor think this is needed.
bit unclear about whio is right here.

Comment made about arrows on back of tiles helpful, I have heard of this but are arrows to help with bowing tiles or direction of marking on top of tile.

tiles weigh 40 kgs each.
not worried about that as used to fixing large limestone tiles.
just feel that porcelain is different and may be more difficult to bed down solid.
a mentioned before the thought of using a semi porable which i would never normally use sounds good as the subfloor is dead flat, I wont have to bed tiles up unless they are bowed.

HAS ANYONE ACTUALLY FIXED A 15MM PORCELAIN TILE AS BIG AS THIS.
I WILL ALSO NEED TO BUY A VERY GOOD BLADE. HAVE A WET CUTTER THAT CUTS UP TO 1200MM AND TAKES A 350MM BLADE.
DONT MIND SPENDING THE MONEY JUST WANT THE BEST BLADE AS GOT 150 LIN MTS SKIRTINGS TO CUT FROM TILES AS WELL

hi the arrow in question is called a directional arrow shows the way tile has passed through machine there for grain in tile lines up if all laid the same way also helps with size variation , the bow is of concern let client know of your issues as you wont know until tiles are on site make sure they all come from same batch to as this will be an issue i have laid this size before not enjoyable the adh dave recomends seems right and more suited to your situation you may find they will cut on a normal tile cutter might be worth a try you may need to check your notch trowl size dont be scared to increase notch size with the bow you mentioned

Originally Posted by mags

£24 for a 20kg bag

Knock a tenner off that for the kera flex maxi...

Originally Posted by mags

£24 for a 20kg bag

wouldent leave me any thing for labour how can they warrant that

Originally Posted by jonnyc

substrate is the dreaded anhydrite.
but has been down 4 months and underfloor heating now being brought up to temperature and down over 9 days.
House is water tight no wet trades to pull more moisture in, so cant ask for any more than that.
will prime with p51 or similar.
There will be dilex bwb 15mm movement joints in tiles through all doorways and have suggested cuttting a 30mm deep joint in to anhyrdite screed directly under these tile movement joints to force a weak spot.
Have recommended ditra as well but contractor does nor think this is needed.
bit unclear about whio is right here.

Comment made about arrows on back of tiles helpful, I have heard of this but are arrows to help with bowing tiles or direction of marking on top of tile.

tiles weigh 40 kgs each.
not worried about that as used to fixing large limestone tiles.
just feel that porcelain is different and may be more difficult to bed down solid.
a mentioned before the thought of using a semi porable which i would never normally use sounds good as the subfloor is dead flat, I wont have to bed tiles up unless they are bowed.

HAS ANYONE ACTUALLY FIXED A 15MM PORCELAIN TILE AS BIG AS THIS.
I WILL ALSO NEED TO BUY A VERY GOOD BLADE. HAVE A WET CUTTER THAT CUTS UP TO 1200MM AND TAKES A 350MM BLADE.
DONT MIND SPENDING THE MONEY JUST WANT THE BEST BLADE AS GOT 150 LIN MTS SKIRTINGS TO CUT FROM TILES AS WELL

Yes no problems

Substrate is the dreaded anhydrite.

Have to prepped one of these before...? not as straight forward as you think..

I have primed the last 3 anhydrite screeds I did and used the mapei primer an the mapei adhesive you recommended.
did it twice wih roller. no problems to date.
Other screeds did not have this latence that needs to be taken off. this one had that and screed company came back to take top skin off.
I have to say dave , there seems to be alot of ignorance about these screeds. I get so much conflicting info so good to hear from an expert.

Have you come across the clinker terracotta tiles that are laid straight on top of panels with underfloor heat pipes on top of a concrete base. they lock in together.
did one of these few months back but its all down to the concrete base being level or latexing over base before puttingtiles down.
Yet another german system but i was very impressed with it.
like all things good more expensive to lay, but floor warms quick as 25mm thick and being terracotta retains heat well.
dont remember company name but they were in chobahm surrey.

one of the key plusses was that you need no expansion joints except round perimeter of room.