Best adhesive for fixing Marmox boards to bathroom chipboard floor

[JimboD]

Hi,

I was going to use some Mapei Super Flexible Adhesive I have kicking about (which I've just found out is specially fomulated for B&Q - which is ringing alarm bells as I'm sure it will likely be inferior). I rang Mapei and they said dont use that! Instread, sand the floor to create a key, then use Keraquick mixed with Latex plus. Then lay the ufh cover in slc and then use the same keraquick/latex mix to tile.

A pricey option but I guess is belt and braces. I've 8m2 to board/tile.

Do you folks agree this would be best (I will be screwing the boards at 8" intervals and the floor has no bounce as far as I can tell)

I see on this site its often recommended to just us a single part BAL flex for both? I can get that locally, so am just figuring out what's best to do. (I can tack the Mapei Super Flexible stuff back so no cost implication there).

I dont mind spending the extra £150 but only if merited.

The tiles are 120mmx800mm (plank like) which might make them more or less suseptable to cracking (narrow so less inherent strength vs narrow so more able to move independantly in bed of flex adhesive)

Thoughts appreciated
Cheers
Jim

 

[Rookery]

I'd fix the boards with Mapei Keraquick, flood the cables with Weber Floorflex and fix the tiles with Keraquick. I wouldnt bother with the latex. Other adhesives such as BAL RSF would be ok too, it depends on availability and price in your area.

 

[JimboD]

I'd fix the boards with Mapei Keraquick, flood the cables with Weber Floorflex and fix the tiles with Keraquick. I wouldnt bother with the latex. Other adhesives such as BAL RSF would be ok too, it depends on availability and price in your area.

Yes, I'm not sure why I need a 2 part with the expensive Latex if the boards are being screwed at 200mm centres anyway. Can the extra flex in the adhesive make any difference when the board is screwed?

 

[JimboD]

I was thinking about this last night.
With the combination Chipboard:S2:6mm insulation board(Marmox):UFH:SLC:S1:tile

Then if there is any movement in the chipboard (eg up and down due to floor bounce) the insulation board will stay still BUT the fixing screw will move placing a load on the SLC and S1/tile combo.

Could this not place localized pressure on the tiles and cause a failure/crack?