question about mesh v's ditra - Tile Advice

[Blunt Tool]

Sorry I am definitely not trying to justify the builders work. I am just quoting from b and q website to provide more details on osb. Thanks so much for trying to help!
I don't have more photos tonight, can get more tomorrow. There is grey flexible adhesive under that tile, builder says he is using extra adhesive because of mesh. Thanks so much for all the comments and help so far!

Would advise stop all works on tiling and boarding till sorted out!

 

[Old Mod]

I can't quote BS 5385, but to the best of my knowledge, osb/sterling board is not a suitable material to tile to, for that matter, no timber is.
It is too susceptible to external forces like heat/cold and moisture, even more so with a particle board.
And I certainly wouldn't swear by any technical description from B&Q/Trade-Point web site. They are two of the worst sites imaginable.
If your architect has spec'd 'Hardboard' technically that is also incorrect.
It would depend on his definition, it's ambiguous at best.
There are so many better options out there.
And tbh, if this mesh is as good or better than Ditra 25, why aren't we all using it?
Yes in certain circumstances it can add stability to a surface, but it is NOT a decoupling membrane, as was stated on your spec.

 

[John Benton]

I've seen quite a few failures tiling onto OSB along with other types of timber. Agree completely with Antonio after looking at the accompanying video, maybe cheaper for the material but it's certainly more labour intensive, also not a decoupler. I would steer well clear!!!

 

[GAZ5518]

IMO....OSB Board is primaraly used for flat roofs or sheds which are felted etc afterwards...not really a suitable substrate for tiling on.... But if you are accepting the B&Q description ... Then you absolutely should screw it down..6" centres ..... Over laying with a de coupling Mat as described before( Ditra, Bal...etc)
Your architect should be aware of the correct products ... and procedures... (as should your builder).....although he/she stating "Hardboard" would concern me..
Don't proceed and take heed of all the advice that is available to you on this site ..... It will save you Money and stress in the long run ....Hope all goes well...

 

[Two-Trowels]

Hardi (backer) board perhaps?????

 

[Flintstone]

Updates ?

 

[One Day]

OSB is used routinely in the states but it's massively better even than our osb3.
Personally I wouldn't fix anything to uk grade osb. I even have my doubts too as to wbp ply.