Trowel size for mosaic on floor

[reeshar]

Looking for a bit of advice on what size of trowel to use for a mosaic laid on the floor. The individual tiles are 50mm square, and porcelain (if that has any bearing on it). The floor is perfectly flat, although it is plywood. I lifted the original floorboards, braced all the joists (450mm centres), fitted noggins to support all the cut edges, and laid 25mm WBP ply screwed with Spax screws at 150mm centres. I also primed the underside and cut faces of the ply.

I'm worried about getting loads of adhesive up through the gaps in the mosaic (mesh backed) so advice on trowel size appreciated. I'm planning to use Mapei Keraflex Slowset.

Final query - I don't have to prime the face of the ply being tiled as far as I understand, is that right?

Cheers,

Richard

 

[Boggs]

Anyone . . . .

 

[Unused Account 1]

Prime it anyway for how long it takes ,whats the thickness of the tile,

 

[Bond]

Shouldn’t be to much suction with WBP ply, however best to to give it a clean with a damp sponge and prime.

 

[hmtiling]

I'm guessing they'll be 9/10mm thick. I'd go for a 6mm notch if so. I'd overboard the floor with a 6mm cement board though

 

[reeshar]

Thanks for replies guys. They're 7mm thick. Would a 6mm notched trowel be ok for adhesive squeezing up between tiles? What primer would you use, Primer G?

 

[Bond]

Thanks for replies guys. They're 7mm thick. Would a 6mm notched trowel be ok for adhesive squeezing up between tiles? What primer would you use, Primer G?

I would stick with the 6mm your spreading at a approx 45 degree angle, so should be fine. As a primer l generally use SBR for most backgrounds, if your tiling direct to WBP ply it might be worth giving it a key with coarse grip sandpaper first, as some hardwood veneers can have a smooth almost oily surface.

 

[Tiler Durden]

Thin bed solid bed trowel but not the ‘tipped’ version, the standard tapered.

 

[Dougs Third Go]

I'd have thought a 4mm, just to stop adhesive squidging through the joints.

 

[Flintstone]

4mm is very small for a porcelain mosaic. Id be starting with the 6mm. Also as above, i wouldn't tile to the ply

 

[Dougs Third Go]

4mm is very small for a porcelain mosaic. Id be starting with the 6mm. Also as above, i wouldn't tile to the ply

but when you bed them in the excess addy has to go somewhere and nothing worse than filling the joints and having to scrape them out to get a decent depth for grout.

 

[Tiler Durden]

4mm is too thin for me on a floor. It increases the potential of tiles to be actually touching the sub floor. That’s why I suggested the thin bed solid bed tapered 6mm trowel. Don’t forget that trowel technique is a factor. Every Tiler might have their own way to comb the adhesive and can achieve similar results with different trowels. Perhaps no choice using a 4mm on very thin mosaics but these are porcelain so likely to be between 8 and 10mm thick.

 

[Dougs Third Go]

4mm is too thin for me on a floor. It increases the potential of tiles to be actually touching the sub floor. That’s why I suggested the thin bed solid bed tapered 6mm trowel. Don’t forget that trowel technique is a factor. Every Tiler might have their own way to comb the adhesive and can achieve similar results with different trowels. Perhaps no choice using a 4mm on very thin mosaics but these are porcelain so likely to be between 8 and 10mm thick.

op quoted tiles as being 7mm thick so on the assumption that a solid bed needs twice it's depth of notch to create a solid bed I'd say 4mm would be adequate, as long as a wiggle down was applied.

 

[Tiler Durden]

Oh yeah, I had to go back and check and he does indeed suggest they are 7mm thick. Yes 6mm might be too thick.

 

[reeshar]

Just to add an update to this, first of all thank you for all your comments, it was much appreciated. I decided to go for a tipped notched trowel I picked up, which was basically a standard 3mm notched trowel with two little carbide lugs at either end of the trowel. This laid a solid screed 3mm thick, with a combed surface of an extra 3mm above it. Sorry if this is basic info, I'm writing it all out for whoever might stumble across these posts in future looking for ideas on the same issue. The tiles have been down a month or so now and are solid as a rock, very happy with how it's gone. First real tiling project!

Cheers again guys for your advice and ideas.