grout cracking - TilersForums.com

[Andrew Case]

I think it's nice and encouraging to see someone putting a job right rather than running or leaving it as is! I don't know if this is your house or a customers but either way it would have been easier to leave it, but youve asked the questions and are putting it right. Good for you.

 

[Brian the Tile]

Got to agree with you there fully Martino,a very good point made,to many people on here think its wrong to use ply,and a lot of people have only been on courses where they have been told not to use it,in my eyes experience speaks for itself,not a lot will pay a small fortune for something that is not needed in my neck of the woods neither

 

[Ajax123]

i have seen this used before and it was fine!!

Then you were lucky........ 6mm much too thin.

 

[ythan]

If the tiles are firmly stuck down and none have cracked, then why not just carefully re-grout.

The size of the floor looks too small to have a major problem with shrinkage of the ply etc

Cement boards don't add any flexural strength to the floor, in fact less so than 6mm ply. Thicker ply (15mm+) is normally used where the existing floor is too flexible between joists or over floor boards. (Assume that your floor was pretty solid?).
Cement boards on a flexible floor will result in tiles cracking.

 

[andy-p]

I only use 6mm cement boards on bathroom floors now , the cost is not much more than ply but the advantages are 10 fold , easy to transport, cut , fix and its waterproof as well , when fitted correctly to a properly prepared substrate , the cement boards are SOLID when compared to ply.. i still have to fix to 12mm ply when subbing to certain Bathroom fitters who prep the jobs and all seems good but i much prefer cement boards..

 

[ythan]

Jace158's original query was about grout cracking and many said 6mm ply overlay is the problem - and that jace158 has to start again using cement boards- some even said need to remove the ply overlay first.

That's all a massive messy job for both jace158 and his customer. I'm doubtful that is necessary and hence suggested to first try careful re-grouting. There's no mention of cracking of the tiles, so jace158's problem sounds minor. Tiling onto ply and onto chipboard floors can be successful.


I agree in bathrooms, particularly when using electric underfloor heating, then thermal backer boards (eg Warmup Insulation boards) are well worth laying. But I maintain that 6mm cement backer boards won't be a cure for flexible ply or chipboard floors -cement boards don't add much flexural strength to the existing floor, compared with a ply overlay (which only needs to be thoroughly clout nailed).

 

[dave l and l]

whether you carefully re grout or not you wont be fixing the problem as all you are doing is covering up. there is a problem that needs to be remedied. my belief is the 6mm substrate is not thick enough to deal with foot traffic so i believe you would have to lift and fix properly,

 

[Bathfix Bob]

I'm a firm believer in cement boards don't get me wrong I never use anything else after a similar disaster with 12mm ply, in my case the grout was fine but the tiles cracked in a perfect line over where two boards met. In that case there wern't enough screws and the edges were lifting.

Re the 6mm thickess, Hardiebacker are 6mm but they are bedded onto flexi adhesive to fill voids and stop them bouncing over hollows in old floorboards.

So my question is, if the subfloor was 100% flat then surely 6mm ply screwed and 150mm would be okay as there's nothing to 'compress'?

 

[White Room]

Jace158's original query was about grout cracking and many said 6mm ply overlay is the problem - and that jace158 has to start again using cement boards- some even said need to remove the ply overlay first.

That's all a massive messy job for both jace158 and his customer. I'm doubtful that is necessary and hence suggested to first try careful re-grouting. There's no mention of cracking of the tiles, so jace158's problem sounds minor. Tiling onto ply and onto chipboard floors can be successful.


I agree in bathrooms, particularly when using electric underfloor heating, then thermal backer boards (eg Warmup Insulation boards) are well worth laying. But I maintain that 6mm cement backer boards won't be a cure for flexible ply or chipboard floors -cement boards don't add much flexural strength to the existing floor, compared with a ply overlay (which only needs to be thoroughly clout nailed).

You can't be serious ????

 

[Andrew]

It is certainly dependent on budget, hence I'm sorry to be a snob but I will only work on projects where the budget allows you to do things properly!