cracking grout

[andy_t_uk]

It was a concrete foundation and I seem to remember him laying down a membrane and screed then fixing the boards to this base.

Would you suggest boarding out the whole area? if so what boarding would be best and what addy/grout combination?

 

[Andy Allen]

why did he put board on the screed? why not just screed to the right level?

 

[andy_t_uk]

haven't the foggiest - wasn't into DIY at the time so just let him get on with it

 

[TileGiant Macc]

Hi Andy,
Mapei technical advise that using P.V.A can sometimes have the adverse effect with adhesive and refer the cement-based adhesive back to a liquid state (although cases of this are rarely heard of), a recommended 'Primer G' from most Mapei suppliers. Going by what you've mentioned it could be one of many situations, and so stripping it and starting from scratch will ultimately be the best option. If it was movement within the floorboards itself then most likely the tiles and/or grout will break in correlation to the joints. If not it could be the case of either the adhesive or floor not bonding together sufficiently. Either way my best advice is to lift the tiles and investigate before the situation deteriorates!
The benefit of using powdered grout is that it comes with the additives of flexibility, waterproof and the fight against blackspot and mould.

Hope this helps!

 

[andy_t_uk]

Hi TileGiant Macc - thanks for the advice - would you suggest priming the area in a different way or boarding over the area - if boarding is the best way how do I go about this?

 

[TileGiant Macc]

Hi Andy,
Which adhesive product did you use?

 

[andy_t_uk]

I really can't remember - a powder adhesive bought from a discout tiles store - was recommended as the best one for wooden surfaces.

 

[TileGiant Macc]

Hi Andy,
Best advice is to get it all up and start again. It could be that the wood is contracting and expanding with heat or even moisture, or it could just be dry flakey grout. There are cases where grout cracks on solid floors. If you're not pleased with the tiling and have a spare weekend.....

 

[Mike]

regarding the substrate, you say it's concrete, are you sure it's not bison beam construction? (beams and blocks over the hollow floor then insulation and floor boards)

 

[andy_t_uk]

Thanks for all the advice lads - going to take it all up and give it another go

Really appreciate all the pointers