uneven ply floor - suggestions please? - Tile Advice

[Grace'sDad]

I have a customer who has plyed his bathroom floor with 18mm wbp, screwed well into joists. movement is negligible but he wants large format square edged porcs fixing brick-bond. One half of the floor is nice and flat, but the other half slopes approx 15mm over 1.5m (approx 600mm wide).
I was going to use mapei fiberplan to build up the floor, but can't get any in this backwater town!
Bearing in mind that perfection is the minimum acceptable standard for these tiles, how would you sort the floor?

Oh, and I am fitting loose cable ufh, so will need a slc suitable for this anyways! Was going to use BAL Fastflex and microcolour with GT40 admix.

 

[bigandy]

I know that tilemart used to stock mapei some time ago, and there is one in preston.
Or look at building the floor up with some hardibacker or similar product(although i would then be looking at an uncoupling membraine as well)

 

[Grace'sDad]

Thanks BigAndy. Tile mart don't carry it, but they do have this Levelflex - Tilemaster Adhesives Wall Floor tile Grout Adhesive :: tilemasteradhesive.co.uk
priced at £15.50 per 20kg.

Might be worth a try....

 

[oldgit]

im fairly certain you can use bal pourable thickbed for the leveling up

 

[grumpygrouter]

CTD Warrington should do Fiberplan Dad. Bit of a trip from preston but it may be worth a trip to pick up a few bags. Also, you can get away with SPF or Rapidset flexy with 18mm ply down. Any particular reason why you want to use fastflex?

 

[Grace'sDad]

Mainly as I don't like ply in bathrooms with ufh - too many variables!
Also, it has been plyed with about 7 pieces over 8sqm, rather than 3 or 4 large sheets. More chance of lateral expansion?

 

[grumpygrouter]

Mainly as I don't like ply in bathrooms with ufh - too many variables!
Also, it has been plyed with about 7 pieces over 8sqm, rather than 3 or 4 large sheets. More chance of lateral expansion?

Hmmm, I see, Fair enough.

 

[Sully]

If you speak with BAL or Ardex, they'll strongly advise against using UFH over ply. Thermal expansion can result in failure. I know that some tilers will fix, but I won't after having conversations with both their tech departments. Overboard with insulation boards and level with slc would be my way. Yes - I know the step issues but better a step than a failed floor which could be pretty expensive to put right.

Andrew