Marble Floor Tiles - Hairline Cracks

[Stef]

Why did you fit ply on top of tile backer boards?
Was tile backer boards glued & screwed to the subfloor?
Should have fitted 6mm ply then the backer boards, not ideal but would have given u more of a chance.
There should have been a decoupler fitted as soon as you introduced heat into the floor.

 

[Kevbos]

Everyone forgot to ask when heating was turned on .that is big problem if turned on too early after fixing tiles .firstly floor not strong enough .then weak tiles .but if you turn heating on too quick everything shrinks and tiles cracking suggests this .As they not lifting but cracking .3 to 4 weeks before heating goes on .then lowest setting 2 weeks then increase slowly .your tiles cracked because they are weakest point .think of the buckets of water that went into that floor .

 

[Alzak]

Hi All,

Many Thanks for replies appreciate support.

Heating was not switched on yet as I knew about giving some time for floor to settle before heat is introduced.

Reason for PLY above hardie was to add some extra strength, hardie was in 4 pieces (put using brick fashion) and PLY was in one piece thats why I thought it would be much better to install PLY above hardie... looks like this was my mistake oh well you live and learn,

I don't really want to rip this floor apart (definitely for now) so would try to live with those cracks, I noticed some of those cracks appeared in natural veins of the tiles and then spread across.

Worst thing is that I bought uncoupling membrane but decided against using it as floor is raised by about 40mm already (with tiles adhesive,self leveling, ply and hardie) so didn't wanted to add additional height...

Self leveling used is Mapei Ultraplan thickness around 6-10mm.

Back home we have electric heating(wet)and natural stone on ground floor in my parents house without any hardie boards or uncoupling membrane and it is fine for past 15 years or so... but looks like first floor wooden subfloor is probably not best option for stone without a proper preparation.

 

[Stef]

You say Mapei ultraplan was used, was it ultraplan Eco or renovation screed?

 

[Alzak]

It is renovation screed

 

[Stef]

It is renovation screed

No problems with that then as it's a fibre leveller.