Using tile adhesive to flatten floor?

[bigd]

Hi, my bathroom has the usual green chipboard floor which has a dip in it of up to 10mm due to a couple of low joists which appear to have been like that since the house was built 17 years ago and not movement.

I'm looking to use 6mm cement boards as a base for tiling but want to start with a flat surface under them, would an SPF adhesive like Keraflex Maxi be ok for this? I'd then use the same adhesive on top to lay the tiles. I have put a ton of extra screws into the floor already and it doesn't seem to bounce at all, glass of water on floor, jump up and down etc.

The floor is flat in the other direction but does run off from one side to the other which i am fine with but means I don't want to use a product that will run like SLC. Replacing the floor isn't possible due to walls running across the floor and the door is at the low point and I don't want to raise it that much.

Any help appreciated as always.

 

[Spud]

why are you reluctant to use leveling compound ?

 

[bigd]

Hi Gary, as i said there is a run off in the opposite direction to the dip I want to level, about 25mm over 3m, so I don't want to use something that will 'run down' the slope, I thought tile adhesive would stay where i put it.

 

[david campbell]

creat a shutter

 

[bigd]

Think you've missed what i meant, I'm not looking to fix the direction it slopes in JUST the dip in the opposite direction, if I levelled the whole floor the doorway would be an inch higher before I lay the boards and tiles! Hence, a product that runs is no good to me.

I'm looking for flat NOT level.

 

[DHTiling]

Mix the SLC thicker and it will not run..lol lol..

PCI HSP34 is great for thicker applications on timber.

 

[Dave Ramsden]

Mix the SLC thicker and it will not run..lol lol..

PCI HSP34 is great for thicker applications on timber.

Dave isnt gonna let you repair with SPF by the looks of things!

 

[grumpygrouter]

If you wanted to use adhesive, you would need to build up in layers to avoid shrinkage and cracking. A Good SLC appropriately mixed would give a better finish and quicker time to lay lay your boards. Keraflex maxi my just do the job for the fill but you are pushing it's limits but you are probably better off with an S2 class adhesive onto timber.

 

[bigd]

Is it OK to mix it thick enough so it doesn't self level? The one thing i thought I'd learnt from all my reading on here is you stick to the manufacturers instructions exactly. Where would I get PCI HSP34 from as Google isn't being my friend today.

I was asking about the Maxi as it's supposed to be good for up to 15mm in one hit and I only need 10mm, that and I've got some left over from the walls and it's easy for us non trade bods to get at a reasonable price and at sensible times of the day, but i want to do a good job or i wouldn't have asked

Thanks for the replies.

 

[Scott]

Cant you infil will 9mm ply to reduce the depth and then use adhesive or SLC? Personally id cut out the problem sheets and pack off the low joists

 

[ScottG13]

Personally id cut out the problem sheets and pack off the low joists

My thoughts exactly.

 

[Bolter]

Is it OK to mix it thick enough so it doesn't self level?

yes, and with a straight edge, pull the slc over the dip one way. Then add a little more if needed, and pull it back the other way. Once there is enough down to fill the dip, pull the straight edge back and forth across the dip a couple of times.

Wait for it to go off. Needs to be off enough to be able to walk on it. Then go back into the room and with a sharper edged straight edge, shave the floor down. You know, all the little snots and drips and little high spots etc. Rub them all down, sweep up, and let it fully cure.

Take your time and you'll get a really flat floor

(the best slc is the stuff that comes with a large bottle of white liquid additive and a big bag of powder. )

 

[bigd]

Cool, thanks Bolter. That's the sort of technique I was going to use with the adhesive but more than happy to do it with thick SLC, can you recommend a brand us mere mortals can find easily.

Scottly and Scott, as i said in the original post, replacement isn't going to work due to the location of stud walls, otherwise i would've started there, thanks anyway.

 

[Bolter]

Cool, thanks Bolter. That's the sort of technique I was going to use with the adhesive but more than happy to do it with thick SLC, can you recommend a brand us mere mortals can find easily.

Latex Plan 20kg Two Part Flexible Self Levelling Compound - Floor Tile Adhesive - Tile Adhesive & Grout

 

[Andy Tiler]

Hi, my bathroom has the usual green chipboard floor which has a dip in it of up to 10mm due to a couple of low joists which appear to have been like that since the house was built 17 years ago and not movement.

I'm looking to use 6mm cement boards as a base for tiling but want to start with a flat surface under them, would an SPF adhesive like Keraflex Maxi be ok for this? I'd then use the same adhesive on top to lay the tiles. I have put a ton of extra screws into the floor already and it doesn't seem to bounce at all, glass of water on floor, jump up and down etc.

The floor is flat in the other direction but does run off from one side to the other which i am fine with but means I don't want to use a product that will run like SLC. Replacing the floor isn't possible due to walls running across the floor and the door is at the low point and I don't want to raise it that much.

Any help appreciated as always.

hi bigd if uve got some bagged adhesive left over from the walls fill in the floor where needed useing a straight edge making it flat. once dry go over the floor with the same adhesive useing a 6mm notch trowel stick and screw your boards down following manufactures instructions the adhesive wont be going anywhere because it will be sandwiched between the floor and the boards you dont need to go out spending more money just make sure you use an spf adhesive to stick ure tiles.hope this helps